针对 Java List 相关的一些操作进行说明和示例
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core-java-modules/core-java-collections-list/README.md
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core-java-modules/core-java-collections-list/README.md
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## Core Java Collections List
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This module contains articles about the Java List collection
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### Relevant Articles:
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- [Java – Get Random Item/Element From a List](http://www.baeldung.com/java-random-list-element)
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- [Removing all nulls from a List in Java](http://www.baeldung.com/java-remove-nulls-from-list)
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- [Removing all duplicates from a List in Java](http://www.baeldung.com/java-remove-duplicates-from-list)
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- [How to TDD a List Implementation in Java](http://www.baeldung.com/java-test-driven-list)
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- [Iterating Backward Through a List](http://www.baeldung.com/java-list-iterate-backwards)
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- [Remove the First Element from a List](http://www.baeldung.com/java-remove-first-element-from-list)
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- [How to Find an Element in a List with Java](http://www.baeldung.com/find-list-element-java)
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- [Finding Max/Min of a List or Collection](http://www.baeldung.com/java-collection-min-max)
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- [Remove All Occurrences of a Specific Value from a List](https://www.baeldung.com/java-remove-value-from-list)
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- [[Next -->]](/core-java-modules/core-java-collections-list-2)
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core-java-modules/core-java-collections-list/pom.xml
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core-java-modules/core-java-collections-list/pom.xml
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<?xml version="1.0" encoding="UTF-8"?>
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<project xmlns="http://maven.apache.org/POM/4.0.0"
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xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
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xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
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<modelVersion>4.0.0</modelVersion>
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<artifactId>core-java-collections-list</artifactId>
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<version>0.1.0-SNAPSHOT</version>
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<name>core-java-collections-list</name>
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<packaging>jar</packaging>
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<parent>
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<groupId>com.ossez.core-java-modules</groupId>
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<artifactId>core-java-modules</artifactId>
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<version>0.0.2-SNAPSHOT</version>
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<relativePath></relativePath>
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</parent>
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<dependencies>
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<dependency>
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<groupId>org.apache.commons</groupId>
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<artifactId>commons-collections4</artifactId>
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<version>${commons-collections4.version}</version>
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</dependency>
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<dependency>
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<groupId>org.apache.commons</groupId>
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<artifactId>commons-lang3</artifactId>
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<version>${commons-lang3.version}</version>
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</dependency>
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</dependencies>
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</project>
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package com.baeldung.findanelement;
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public class Customer {
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private int id;
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private String name;
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public Customer(int id, String name) {
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this.id = id;
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this.name = name;
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}
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public int getId() {
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return id;
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}
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public String getName() {
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return name;
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}
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@Override
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public int hashCode() {
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return id * 20;
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}
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@Override
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public boolean equals(Object obj) {
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if (obj instanceof Customer) {
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Customer otherCustomer = (Customer) obj;
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if (id == otherCustomer.id)
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return true;
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}
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return false;
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}
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}
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package com.baeldung.findanelement;
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import java.util.Iterator;
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import java.util.List;
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import org.apache.commons.collections4.IterableUtils;
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import com.google.common.base.Predicate;
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import com.google.common.collect.Iterables;
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public class FindACustomerInGivenList {
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public Customer findUsingGivenIndex(int indexOfCustomer, List<Customer> customers) {
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if (indexOfCustomer >= 0 && indexOfCustomer < customers.size())
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return customers.get(indexOfCustomer);
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return null;
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}
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public int findUsingIndexOf(Customer customer, List<Customer> customers) {
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return customers.indexOf(customer);
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}
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public boolean findUsingContains(Customer customer, List<Customer> customers) {
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return customers.contains(customer);
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}
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public Customer findUsingIterator(String name, List<Customer> customers) {
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Iterator<Customer> iterator = customers.iterator();
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while (iterator.hasNext()) {
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Customer customer = iterator.next();
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if (customer.getName().equals(name)) {
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return customer;
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}
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}
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return null;
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}
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public Customer findUsingEnhancedForLoop(String name, List<Customer> customers) {
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for (Customer customer : customers) {
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if (customer.getName().equals(name)) {
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return customer;
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}
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}
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return null;
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}
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public Customer findUsingStream(String name, List<Customer> customers) {
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return customers.stream()
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.filter(customer -> customer.getName().equals(name))
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.findFirst()
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.orElse(null);
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}
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public Customer findUsingParallelStream(String name, List<Customer> customers) {
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return customers.parallelStream()
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.filter(customer -> customer.getName().equals(name))
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.findAny()
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.orElse(null);
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}
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public Customer findUsingGuava(String name, List<Customer> customers) {
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return Iterables.tryFind(customers, new Predicate<Customer>() {
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public boolean apply(Customer customer) {
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return customer.getName().equals(name);
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}
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}).orNull();
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}
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public Customer findUsingApacheCommon(String name, List<Customer> customers) {
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return IterableUtils.find(customers, new org.apache.commons.collections4.Predicate<Customer>() {
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public boolean evaluate(Customer customer) {
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return customer.getName().equals(name);
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}
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});
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}
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}
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package com.baeldung.java.list;
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import java.util.Arrays;
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import java.util.Collection;
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import java.util.Iterator;
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import java.util.List;
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import java.util.ListIterator;
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public class CustomList<E> implements List<E> {
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private Object[] internal = {};
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@Override
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public boolean isEmpty() {
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// the first cycle
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// return true;
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// the second cycle
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// if (internal.length != 0) {
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// return false;
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// } else {
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// return true;
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// }
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// refactoring
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return internal.length == 0;
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}
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@Override
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public int size() {
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// the first cycle
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// if (isEmpty()) {
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// return 0;
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// } else {
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// return internal.length;
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// }
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// refactoring
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return internal.length;
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}
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@SuppressWarnings("unchecked")
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@Override
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public E get(int index) {
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// the first cycle
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// return (E) internal[0];
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// improvement
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return (E) internal[index];
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}
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@Override
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public boolean add(E element) {
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// the first cycle
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// internal = new Object[] { element };
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// return true;
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// the second cycle
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Object[] temp = Arrays.copyOf(internal, internal.length + 1);
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temp[internal.length] = element;
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internal = temp;
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return true;
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}
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@Override
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public void add(int index, E element) {
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throw new UnsupportedOperationException();
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}
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@Override
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public boolean addAll(Collection<? extends E> collection) {
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throw new UnsupportedOperationException();
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}
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@Override
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public boolean addAll(int index, Collection<? extends E> collection) {
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throw new UnsupportedOperationException();
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}
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@Override
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public E remove(int index) {
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throw new UnsupportedOperationException();
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}
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@Override
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public boolean remove(Object object) {
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throw new UnsupportedOperationException();
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}
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@Override
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public boolean removeAll(Collection<?> collection) {
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throw new UnsupportedOperationException();
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}
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@Override
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public boolean retainAll(Collection<?> collection) {
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throw new UnsupportedOperationException();
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}
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@Override
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public boolean contains(Object object) {
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for (Object element : internal) {
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if (object.equals(element)) {
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return true;
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}
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}
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return false;
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}
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@Override
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public boolean containsAll(Collection<?> collection) {
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for (Object element : collection)
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if (!contains(element)) {
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return false;
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}
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return true;
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}
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@SuppressWarnings("unchecked")
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@Override
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public E set(int index, E element) {
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E oldElement = (E) internal[index];
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internal[index] = element;
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return oldElement;
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}
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@Override
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public void clear() {
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internal = new Object[0];
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}
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@Override
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public int indexOf(Object object) {
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for (int i = 0; i < internal.length; i++) {
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if (object.equals(internal[i])) {
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return i;
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}
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}
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return -1;
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}
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@Override
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public int lastIndexOf(Object object) {
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for (int i = internal.length - 1; i >= 0; i--) {
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if (object.equals(internal[i])) {
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return i;
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}
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}
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return -1;
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}
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@SuppressWarnings("unchecked")
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@Override
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public List<E> subList(int fromIndex, int toIndex) {
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Object[] temp = new Object[toIndex - fromIndex];
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System.arraycopy(internal, fromIndex, temp, 0, temp.length);
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return (List<E>) Arrays.asList(temp);
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}
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@Override
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public Object[] toArray() {
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return Arrays.copyOf(internal, internal.length);
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}
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@SuppressWarnings("unchecked")
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@Override
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public <T> T[] toArray(T[] array) {
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if (array.length < internal.length) {
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return (T[]) Arrays.copyOf(internal, internal.length, array.getClass());
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}
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System.arraycopy(internal, 0, array, 0, internal.length);
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if (array.length > internal.length) {
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array[internal.length] = null;
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}
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return array;
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}
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@Override
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public Iterator<E> iterator() {
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return new CustomIterator();
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}
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@Override
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public ListIterator<E> listIterator() {
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return null;
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}
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@Override
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public ListIterator<E> listIterator(int index) {
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// ignored for brevity
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return null;
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}
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private class CustomIterator implements Iterator<E> {
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int index;
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@Override
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public boolean hasNext() {
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return index != internal.length;
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}
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@SuppressWarnings("unchecked")
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@Override
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public E next() {
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E element = (E) CustomList.this.internal[index];
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index++;
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return element;
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}
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}
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}
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@ -0,0 +1,80 @@
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package com.baeldung.java.list;
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import java.util.Collections;
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import java.util.List;
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import java.util.ListIterator;
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import org.apache.commons.collections4.iterators.ReverseListIterator;
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import com.google.common.collect.Lists;
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/**
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* Provides methods for iterating backward over a list.
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*/
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public class ReverseIterator {
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/**
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* Iterate using the for loop.
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*
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* @param list the list
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*/
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public void iterateUsingForLoop(final List<String> list) {
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for (int i = list.size(); i-- > 0; ) {
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System.out.println(list.get(i));
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}
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}
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/**
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* Iterate using the Java {@link ListIterator}.
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*
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* @param list the list
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*/
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public void iterateUsingListIterator(final List<String> list) {
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final ListIterator listIterator = list.listIterator(list.size());
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while (listIterator.hasPrevious()) {
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System.out.println(listIterator.previous());
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}
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}
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/**
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* Iterate using Java {@link Collections} API.
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*
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* @param list the list
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*/
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public void iterateUsingCollections(final List<String> list) {
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Collections.reverse(list);
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for (final String item : list) {
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System.out.println(item);
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}
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}
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/**
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* Iterate using Apache Commons {@link ReverseListIterator}.
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*
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* @param list the list
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*/
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public void iterateUsingApacheReverseListIterator(final List<String> list) {
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final ReverseListIterator listIterator = new ReverseListIterator(list);
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while (listIterator.hasNext()) {
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System.out.println(listIterator.next());
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}
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}
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/**
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* Iterate using Guava {@link Lists} API.
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*
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* @param list the list
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*/
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public void iterateUsingGuava(final List<String> list) {
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final List<String> reversedList = Lists.reverse(list);
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for (final String item : reversedList) {
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System.out.println(item);
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}
|
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}
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}
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@ -0,0 +1,31 @@
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package com.baeldung.java_8_features;
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public class Car {
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private String model;
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private int topSpeed;
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|
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public Car(String model, int topSpeed) {
|
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super();
|
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this.model = model;
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this.topSpeed = topSpeed;
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}
|
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|
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public String getModel() {
|
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return model;
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}
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|
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public void setModel(String model) {
|
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this.model = model;
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}
|
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|
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public int getTopSpeed() {
|
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return topSpeed;
|
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}
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||||
|
||||
public void setTopSpeed(int topSpeed) {
|
||||
this.topSpeed = topSpeed;
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||||
}
|
||||
|
||||
|
||||
}
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@ -0,0 +1,27 @@
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package com.baeldung.java_8_features;
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||||
|
||||
public class Person {
|
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private String name;
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private Integer age;
|
||||
|
||||
public Person(String name, int age) {
|
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this.name = name;
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this.age = age;
|
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}
|
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|
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public String getName() {
|
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return name;
|
||||
}
|
||||
|
||||
public void setName(String name) {
|
||||
this.name = name;
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}
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|
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public Integer getAge() {
|
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return age;
|
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}
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||||
|
||||
public void setAge(Integer age) {
|
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this.age = age;
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}
|
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}
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@ -0,0 +1,28 @@
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package com.baeldung.list;
|
||||
|
||||
public class Flower {
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||||
|
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private String name;
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private int petals;
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||||
|
||||
public Flower(String name, int petals) {
|
||||
this.name = name;
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||||
this.petals = petals;
|
||||
}
|
||||
|
||||
public String getName() {
|
||||
return name;
|
||||
}
|
||||
|
||||
public void setName(String name) {
|
||||
this.name = name;
|
||||
}
|
||||
|
||||
public int getPetals() {
|
||||
return petals;
|
||||
}
|
||||
|
||||
public void setPetals(int petals) {
|
||||
this.petals = petals;
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||||
}
|
||||
}
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||||
@ -0,0 +1,18 @@
|
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package com.baeldung.list.listoflist;
|
||||
|
||||
public class Pen implements Stationery {
|
||||
|
||||
public String name;
|
||||
|
||||
public Pen(String name) {
|
||||
this.name = name;
|
||||
}
|
||||
|
||||
public void setName(String name) {
|
||||
this.name = name;
|
||||
}
|
||||
|
||||
public String getName() {
|
||||
return this.name;
|
||||
}
|
||||
}
|
||||
@ -0,0 +1,18 @@
|
||||
package com.baeldung.list.listoflist;
|
||||
|
||||
public class Pencil implements Stationery{
|
||||
|
||||
public String name;
|
||||
|
||||
public Pencil(String name) {
|
||||
this.name = name;
|
||||
}
|
||||
|
||||
public void setName(String name) {
|
||||
this.name = name;
|
||||
}
|
||||
|
||||
public String getName() {
|
||||
return this.name;
|
||||
}
|
||||
}
|
||||
@ -0,0 +1,18 @@
|
||||
package com.baeldung.list.listoflist;
|
||||
|
||||
public class Rubber implements Stationery {
|
||||
|
||||
public String name;
|
||||
|
||||
public Rubber(String name) {
|
||||
this.name = name;
|
||||
}
|
||||
|
||||
public void setName(String name) {
|
||||
this.name = name;
|
||||
}
|
||||
|
||||
public String getName() {
|
||||
return this.name;
|
||||
}
|
||||
}
|
||||
@ -0,0 +1,5 @@
|
||||
package com.baeldung.list.listoflist;
|
||||
|
||||
public interface Stationery {
|
||||
|
||||
}
|
||||
@ -0,0 +1,111 @@
|
||||
package com.baeldung.list.removeall;
|
||||
|
||||
import java.util.ArrayList;
|
||||
import java.util.Iterator;
|
||||
import java.util.List;
|
||||
import java.util.Objects;
|
||||
import java.util.stream.Collectors;
|
||||
|
||||
public class RemoveAll {
|
||||
|
||||
static void removeWithWhileLoopPrimitiveElement(List<Integer> list, int element) {
|
||||
while (list.contains(element)) {
|
||||
list.remove(element);
|
||||
}
|
||||
}
|
||||
|
||||
static void removeWithWhileLoopNonPrimitiveElement(List<Integer> list, Integer element) {
|
||||
while (list.contains(element)) {
|
||||
list.remove(element);
|
||||
}
|
||||
}
|
||||
|
||||
static void removeWithWhileLoopStoringFirstOccurrenceIndex(List<Integer> list, Integer element) {
|
||||
int index;
|
||||
while ((index = list.indexOf(element)) >= 0) {
|
||||
list.remove(index);
|
||||
}
|
||||
}
|
||||
|
||||
static void removeWithCallingRemoveUntilModifies(List<Integer> list, Integer element) {
|
||||
while (list.remove(element))
|
||||
;
|
||||
}
|
||||
|
||||
static void removeWithStandardForLoopUsingIndex(List<Integer> list, int element) {
|
||||
for (int i = 0; i < list.size(); i++) {
|
||||
if (Objects.equals(element, list.get(i))) {
|
||||
list.remove(i);
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
static void removeWithForLoopDecrementOnRemove(List<Integer> list, int element) {
|
||||
for (int i = 0; i < list.size(); i++) {
|
||||
if (Objects.equals(element, list.get(i))) {
|
||||
list.remove(i);
|
||||
i--;
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
static void removeWithForLoopIncrementIfRemains(List<Integer> list, int element) {
|
||||
for (int i = 0; i < list.size();) {
|
||||
if (Objects.equals(element, list.get(i))) {
|
||||
list.remove(i);
|
||||
} else {
|
||||
i++;
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
static void removeWithForEachLoop(List<Integer> list, int element) {
|
||||
for (Integer number : list) {
|
||||
if (Objects.equals(number, element)) {
|
||||
list.remove(number);
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
static void removeWithIterator(List<Integer> list, int element) {
|
||||
for (Iterator<Integer> i = list.iterator(); i.hasNext();) {
|
||||
Integer number = i.next();
|
||||
if (Objects.equals(number, element)) {
|
||||
i.remove();
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
static List<Integer> removeWithCollectingAndReturningRemainingElements(List<Integer> list, int element) {
|
||||
List<Integer> remainingElements = new ArrayList<>();
|
||||
for (Integer number : list) {
|
||||
if (!Objects.equals(number, element)) {
|
||||
remainingElements.add(number);
|
||||
}
|
||||
}
|
||||
return remainingElements;
|
||||
}
|
||||
|
||||
static void removeWithCollectingRemainingElementsAndAddingToOriginalList(List<Integer> list, int element) {
|
||||
List<Integer> remainingElements = new ArrayList<>();
|
||||
for (Integer number : list) {
|
||||
if (!Objects.equals(number, element)) {
|
||||
remainingElements.add(number);
|
||||
}
|
||||
}
|
||||
|
||||
list.clear();
|
||||
list.addAll(remainingElements);
|
||||
}
|
||||
|
||||
static List<Integer> removeWithStreamFilter(List<Integer> list, Integer element) {
|
||||
return list.stream()
|
||||
.filter(e -> !Objects.equals(e, element))
|
||||
.collect(Collectors.toList());
|
||||
}
|
||||
|
||||
static void removeWithRemoveIf(List<Integer> list, Integer element) {
|
||||
list.removeIf(n -> Objects.equals(n, element));
|
||||
}
|
||||
|
||||
}
|
||||
@ -0,0 +1,13 @@
|
||||
<?xml version="1.0" encoding="UTF-8"?>
|
||||
<configuration>
|
||||
<appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
|
||||
<encoder>
|
||||
<pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n
|
||||
</pattern>
|
||||
</encoder>
|
||||
</appender>
|
||||
|
||||
<root level="INFO">
|
||||
<appender-ref ref="STDOUT" />
|
||||
</root>
|
||||
</configuration>
|
||||
@ -0,0 +1,105 @@
|
||||
package com.baeldung.collections;
|
||||
|
||||
import static org.hamcrest.Matchers.containsInAnyOrder;
|
||||
import static org.hamcrest.Matchers.containsInRelativeOrder;
|
||||
import static org.hamcrest.Matchers.hasSize;
|
||||
import static org.junit.Assert.assertThat;
|
||||
|
||||
import java.util.ArrayList;
|
||||
import java.util.Collections;
|
||||
import java.util.HashSet;
|
||||
import java.util.LinkedHashSet;
|
||||
import java.util.List;
|
||||
|
||||
import org.apache.commons.collections4.CollectionUtils;
|
||||
import org.apache.commons.collections4.PredicateUtils;
|
||||
import org.junit.Test;
|
||||
|
||||
import com.google.common.base.Predicates;
|
||||
import com.google.common.collect.Iterables;
|
||||
import com.google.common.collect.Lists;
|
||||
import com.google.common.collect.Sets;
|
||||
|
||||
public class JavaCollectionCleanupUnitTest {
|
||||
|
||||
// tests - removing nulls
|
||||
|
||||
@Test
|
||||
public void givenListContainsNulls_whenRemovingNullsWithPlainJava_thenCorrect() {
|
||||
final List<Integer> list = Lists.newArrayList(null, 1, null);
|
||||
while (list.remove(null))
|
||||
;
|
||||
|
||||
assertThat(list, hasSize(1));
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenListContainsNulls_whenRemovingNullsWithPlainJavaAlternative_thenCorrect() {
|
||||
final List<Integer> list = Lists.newArrayList(null, 1, null);
|
||||
list.removeAll(Collections.singleton(null));
|
||||
|
||||
assertThat(list, hasSize(1));
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenListContainsNulls_whenRemovingNullsWithGuavaV1_thenCorrect() {
|
||||
final List<Integer> list = Lists.newArrayList(null, 1, null);
|
||||
Iterables.removeIf(list, Predicates.isNull());
|
||||
|
||||
assertThat(list, hasSize(1));
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenListContainsNulls_whenRemovingNullsWithGuavaV2_thenCorrect() {
|
||||
final List<Integer> list = Lists.newArrayList(null, 1, null, 2, 3);
|
||||
final List<Integer> listWithoutNulls = Lists.newArrayList(Iterables.filter(list, Predicates.notNull()));
|
||||
|
||||
assertThat(listWithoutNulls, hasSize(3));
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenListContainsNulls_whenRemovingNullsWithCommonsCollections_thenCorrect() {
|
||||
final List<Integer> list = Lists.newArrayList(null, 1, 2, null, 3, null);
|
||||
CollectionUtils.filter(list, PredicateUtils.notNullPredicate());
|
||||
|
||||
assertThat(list, hasSize(3));
|
||||
}
|
||||
|
||||
// tests - remove duplicates
|
||||
|
||||
@Test
|
||||
public void givenListContainsDuplicates_whenRemovingDuplicatesWithPlainJava_thenCorrect() {
|
||||
final List<Integer> listWithDuplicates = Lists.newArrayList(5, 0, 3, 1, 2, 3, 0, 0);
|
||||
final List<Integer> listWithoutDuplicates = new ArrayList<>(new HashSet<>(listWithDuplicates));
|
||||
|
||||
assertThat(listWithoutDuplicates, hasSize(5));
|
||||
assertThat(listWithoutDuplicates, containsInAnyOrder(5, 0, 3, 1, 2));
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenListContainsDuplicates_whenRemovingDuplicatesPreservingOrderWithPlainJava_thenCorrect() {
|
||||
final List<Integer> listWithDuplicates = Lists.newArrayList(5, 0, 3, 1, 2, 3, 0, 0);
|
||||
final List<Integer> listWithoutDuplicates = new ArrayList<>(new LinkedHashSet<>(listWithDuplicates));
|
||||
|
||||
assertThat(listWithoutDuplicates, hasSize(5));
|
||||
assertThat(listWithoutDuplicates, containsInRelativeOrder(5, 0, 3, 1, 2));
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenListContainsDuplicates_whenRemovingDuplicatesWithGuava_thenCorrect() {
|
||||
final List<Integer> listWithDuplicates = Lists.newArrayList(5, 0, 3, 1, 2, 3, 0, 0);
|
||||
final List<Integer> listWithoutDuplicates = Lists.newArrayList(Sets.newHashSet(listWithDuplicates));
|
||||
|
||||
assertThat(listWithoutDuplicates, hasSize(5));
|
||||
assertThat(listWithoutDuplicates, containsInAnyOrder(5, 0, 3, 1, 2));
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenListContainsDuplicates_whenRemovingDuplicatesPreservingOrderWithGuava_thenCorrect() {
|
||||
final List<Integer> listWithDuplicates = Lists.newArrayList(5, 0, 3, 1, 2, 3, 0, 0);
|
||||
final List<Integer> listWithoutDuplicates = Lists.newArrayList(Sets.newLinkedHashSet(listWithDuplicates));
|
||||
|
||||
assertThat(listWithoutDuplicates, hasSize(5));
|
||||
assertThat(listWithoutDuplicates, containsInRelativeOrder(5, 0, 3, 1, 2));
|
||||
}
|
||||
}
|
||||
@ -0,0 +1,158 @@
|
||||
package com.baeldung.findanelement;
|
||||
|
||||
import static org.junit.Assert.*;
|
||||
|
||||
import java.util.ArrayList;
|
||||
import java.util.List;
|
||||
|
||||
import org.junit.Test;
|
||||
|
||||
public class FindACustomerInGivenListUnitTest {
|
||||
|
||||
private static List<Customer> customers = new ArrayList<>();
|
||||
|
||||
static {
|
||||
customers.add(new Customer(1, "Jack"));
|
||||
customers.add(new Customer(2, "James"));
|
||||
customers.add(new Customer(3, "Sam"));
|
||||
}
|
||||
|
||||
private static FindACustomerInGivenList findACustomerInGivenList = new FindACustomerInGivenList();
|
||||
|
||||
@Test
|
||||
public void givenAnIndex_whenFoundUsingGivenIndex_thenReturnCustomer() {
|
||||
Customer customer = findACustomerInGivenList.findUsingGivenIndex(0, customers);
|
||||
|
||||
assertEquals(1, customer.getId());
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenAnIndex_whenNotFoundUsingGivenIndex_thenReturnNull() {
|
||||
Customer customer = findACustomerInGivenList.findUsingGivenIndex(5, customers);
|
||||
|
||||
assertNull(customer);
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenACustomer_whenFoundUsingContains_thenReturnTrue() {
|
||||
Customer james = new Customer(2, "James");
|
||||
boolean isJamesPresent = findACustomerInGivenList.findUsingContains(james, customers);
|
||||
|
||||
assertEquals(true, isJamesPresent);
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenACustomer_whenNotFoundUsingContains_thenReturnFalse() {
|
||||
Customer john = new Customer(5, "John");
|
||||
boolean isJohnPresent = findACustomerInGivenList.findUsingContains(john, customers);
|
||||
|
||||
assertEquals(false, isJohnPresent);
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenACustomer_whenFoundUsingIndexOf_thenReturnItsIndex() {
|
||||
Customer james = new Customer(2, "James");
|
||||
int indexOfJames = findACustomerInGivenList.findUsingIndexOf(james, customers);
|
||||
|
||||
assertEquals(1, indexOfJames);
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenACustomer_whenNotFoundUsingIndexOf_thenReturnMinus1() {
|
||||
Customer john = new Customer(5, "John");
|
||||
int indexOfJohn = findACustomerInGivenList.findUsingIndexOf(john, customers);
|
||||
|
||||
assertEquals(-1, indexOfJohn);
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenName_whenCustomerWithNameFoundUsingIterator_thenReturnCustomer() {
|
||||
Customer james = findACustomerInGivenList.findUsingIterator("James", customers);
|
||||
|
||||
assertEquals("James", james.getName());
|
||||
assertEquals(2, james.getId());
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenName_whenCustomerWithNameNotFoundUsingIterator_thenReturnNull() {
|
||||
Customer john = findACustomerInGivenList.findUsingIterator("John", customers);
|
||||
|
||||
assertNull(john);
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenName_whenCustomerWithNameFoundUsingEnhancedFor_thenReturnCustomer() {
|
||||
Customer james = findACustomerInGivenList.findUsingEnhancedForLoop("James", customers);
|
||||
|
||||
assertEquals("James", james.getName());
|
||||
assertEquals(2, james.getId());
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenName_whenCustomerWithNameNotFoundUsingEnhancedFor_thenReturnNull() {
|
||||
Customer john = findACustomerInGivenList.findUsingEnhancedForLoop("John", customers);
|
||||
|
||||
assertNull(john);
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenName_whenCustomerWithNameFoundUsingStream_thenReturnCustomer() {
|
||||
Customer james = findACustomerInGivenList.findUsingStream("James", customers);
|
||||
|
||||
assertEquals("James", james.getName());
|
||||
assertEquals(2, james.getId());
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenName_whenCustomerWithNameNotFoundUsingStream_thenReturnNull() {
|
||||
Customer john = findACustomerInGivenList.findUsingStream("John", customers);
|
||||
|
||||
assertNull(john);
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenName_whenCustomerWithNameFoundUsingParallelStream_thenReturnCustomer() {
|
||||
Customer james = findACustomerInGivenList.findUsingParallelStream("James", customers);
|
||||
|
||||
assertEquals("James", james.getName());
|
||||
assertEquals(2, james.getId());
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenName_whenCustomerWithNameNotFoundUsingParallelStream_thenReturnNull() {
|
||||
Customer john = findACustomerInGivenList.findUsingParallelStream("John", customers);
|
||||
|
||||
assertNull(john);
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenName_whenCustomerWithNameFoundUsingApacheCommon_thenReturnCustomer() {
|
||||
Customer james = findACustomerInGivenList.findUsingApacheCommon("James", customers);
|
||||
|
||||
assertEquals("James", james.getName());
|
||||
assertEquals(2, james.getId());
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenName_whenCustomerWithNameNotFoundUsingApacheCommon_thenReturnNull() {
|
||||
Customer john = findACustomerInGivenList.findUsingApacheCommon("John", customers);
|
||||
|
||||
assertNull(john);
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenName_whenCustomerWithNameFoundUsingGuava_thenReturnCustomer() {
|
||||
Customer james = findACustomerInGivenList.findUsingGuava("James", customers);
|
||||
|
||||
assertEquals("James", james.getName());
|
||||
assertEquals(2, james.getId());
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenName_whenCustomerWithNameNotFoundUsingGuava_thenReturnNull() {
|
||||
Customer john = findACustomerInGivenList.findUsingGuava("John", customers);
|
||||
|
||||
assertNull(john);
|
||||
}
|
||||
|
||||
}
|
||||
@ -0,0 +1,296 @@
|
||||
package com.baeldung.java.list;
|
||||
|
||||
import static org.junit.Assert.assertArrayEquals;
|
||||
import static org.junit.Assert.assertEquals;
|
||||
import static org.junit.Assert.assertFalse;
|
||||
import static org.junit.Assert.assertNull;
|
||||
import static org.junit.Assert.assertTrue;
|
||||
|
||||
import java.util.ArrayList;
|
||||
import java.util.Collection;
|
||||
import java.util.Iterator;
|
||||
import java.util.List;
|
||||
|
||||
import org.junit.Test;
|
||||
|
||||
public class CustomListUnitTest {
|
||||
@Test
|
||||
public void givenEmptyList_whenIsEmpty_thenTrueIsReturned() {
|
||||
List<Object> list = new CustomList<>();
|
||||
|
||||
assertTrue(list.isEmpty());
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenNonEmptyList_whenIsEmpty_thenFalseIsReturned() {
|
||||
List<Object> list = new CustomList<>();
|
||||
list.add(null);
|
||||
|
||||
assertFalse(list.isEmpty());
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenListWithAnElement_whenSize_thenOneIsReturned() {
|
||||
List<Object> list = new CustomList<>();
|
||||
list.add(null);
|
||||
|
||||
assertEquals(1, list.size());
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenListWithAnElement_whenGet_thenThatElementIsReturned() {
|
||||
List<Object> list = new CustomList<>();
|
||||
list.add("baeldung");
|
||||
Object element = list.get(0);
|
||||
|
||||
assertEquals("baeldung", element);
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenEmptyList_whenElementIsAdded_thenGetReturnsThatElement() {
|
||||
List<Object> list = new CustomList<>();
|
||||
boolean succeeded = list.add(null);
|
||||
|
||||
assertTrue(succeeded);
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenListWithAnElement_whenAnotherIsAdded_thenGetReturnsBoth() {
|
||||
List<Object> list = new CustomList<>();
|
||||
list.add("baeldung");
|
||||
list.add(".com");
|
||||
Object element1 = list.get(0);
|
||||
Object element2 = list.get(1);
|
||||
|
||||
assertEquals("baeldung", element1);
|
||||
assertEquals(".com", element2);
|
||||
}
|
||||
|
||||
@Test(expected = UnsupportedOperationException.class)
|
||||
public void whenAddToSpecifiedIndex_thenExceptionIsThrown() {
|
||||
new CustomList<>().add(0, null);
|
||||
}
|
||||
|
||||
@Test(expected = UnsupportedOperationException.class)
|
||||
public void whenAddAllToTheEnd_thenExceptionIsThrown() {
|
||||
Collection<Object> collection = new ArrayList<>();
|
||||
List<Object> list = new CustomList<>();
|
||||
list.addAll(collection);
|
||||
}
|
||||
|
||||
@Test(expected = UnsupportedOperationException.class)
|
||||
public void whenAddAllToSpecifiedIndex_thenExceptionIsThrown() {
|
||||
Collection<Object> collection = new ArrayList<>();
|
||||
List<Object> list = new CustomList<>();
|
||||
list.addAll(0, collection);
|
||||
}
|
||||
|
||||
@Test(expected = UnsupportedOperationException.class)
|
||||
public void whenRemoveAtSpecifiedIndex_thenExceptionIsThrown() {
|
||||
List<Object> list = new CustomList<>();
|
||||
list.add("baeldung");
|
||||
list.remove(0);
|
||||
}
|
||||
|
||||
@Test(expected = UnsupportedOperationException.class)
|
||||
public void whenRemoveSpecifiedElement_thenExceptionIsThrown() {
|
||||
List<Object> list = new CustomList<>();
|
||||
list.add("baeldung");
|
||||
list.remove("baeldung");
|
||||
}
|
||||
|
||||
@Test(expected = UnsupportedOperationException.class)
|
||||
public void whenRemoveAll_thenExceptionIsThrown() {
|
||||
Collection<Object> collection = new ArrayList<>();
|
||||
collection.add("baeldung");
|
||||
List<Object> list = new CustomList<>();
|
||||
list.removeAll(collection);
|
||||
}
|
||||
|
||||
@Test(expected = UnsupportedOperationException.class)
|
||||
public void whenRetainAll_thenExceptionIsThrown() {
|
||||
Collection<Object> collection = new ArrayList<>();
|
||||
collection.add("baeldung");
|
||||
List<Object> list = new CustomList<>();
|
||||
list.add("baeldung");
|
||||
list.retainAll(collection);
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenEmptyList_whenContains_thenFalseIsReturned() {
|
||||
List<Object> list = new CustomList<>();
|
||||
|
||||
assertFalse(list.contains(null));
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenListWithAnElement_whenContains_thenTrueIsReturned() {
|
||||
List<Object> list = new CustomList<>();
|
||||
list.add("baeldung");
|
||||
|
||||
assertTrue(list.contains("baeldung"));
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenListWithAnElement_whenContainsAll_thenTrueIsReturned() {
|
||||
Collection<Object> collection = new ArrayList<>();
|
||||
collection.add("baeldung");
|
||||
List<Object> list = new CustomList<>();
|
||||
list.add("baeldung");
|
||||
|
||||
assertTrue(list.containsAll(collection));
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenList_whenContainsAll_thenEitherTrueOrFalseIsReturned() {
|
||||
Collection<Object> collection1 = new ArrayList<>();
|
||||
collection1.add("baeldung");
|
||||
collection1.add(".com");
|
||||
Collection<Object> collection2 = new ArrayList<>();
|
||||
collection2.add("baeldung");
|
||||
|
||||
List<Object> list = new CustomList<>();
|
||||
list.add("baeldung");
|
||||
|
||||
assertFalse(list.containsAll(collection1));
|
||||
assertTrue(list.containsAll(collection2));
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenList_whenSet_thenOldElementIsReturned() {
|
||||
List<Object> list = new CustomList<>();
|
||||
list.add("baeldung");
|
||||
Object element = list.set(0, null);
|
||||
|
||||
assertEquals("baeldung", element);
|
||||
assertNull(list.get(0));
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenList_whenClear_thenAllElementsAreRemoved() {
|
||||
List<Object> list = new CustomList<>();
|
||||
list.add("baeldung");
|
||||
list.clear();
|
||||
|
||||
assertTrue(list.isEmpty());
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenList_whenIndexOf_thenIndexZeroIsReturned() {
|
||||
List<Object> list = new CustomList<>();
|
||||
list.add("baeldung");
|
||||
|
||||
assertEquals(0, list.indexOf("baeldung"));
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenList_whenIndexOf_thenPositiveIndexOrMinusOneIsReturned() {
|
||||
List<Object> list = new CustomList<>();
|
||||
list.add("baeldung");
|
||||
list.add(".com");
|
||||
list.add(".com");
|
||||
|
||||
assertEquals(1, list.indexOf(".com"));
|
||||
assertEquals(-1, list.indexOf("com"));
|
||||
}
|
||||
|
||||
@Test
|
||||
public void whenLastIndexOf_thenIndexZeroIsReturned() {
|
||||
List<Object> list = new CustomList<>();
|
||||
list.add("baeldung");
|
||||
|
||||
assertEquals(0, list.lastIndexOf("baeldung"));
|
||||
}
|
||||
|
||||
@Test
|
||||
public void whenLastIndexOf_thenPositiveIndexOrMinusOneIsReturned() {
|
||||
List<Object> list = new CustomList<>();
|
||||
list.add("baeldung");
|
||||
list.add("baeldung");
|
||||
list.add(".com");
|
||||
|
||||
assertEquals(1, list.lastIndexOf("baeldung"));
|
||||
assertEquals(-1, list.indexOf("com"));
|
||||
}
|
||||
|
||||
@Test
|
||||
public void whenSubListZeroToOne_thenListContainingFirstElementIsReturned() {
|
||||
List<Object> list = new CustomList<>();
|
||||
list.add("baeldung");
|
||||
List<Object> subList = list.subList(0, 1);
|
||||
|
||||
assertEquals("baeldung", subList.get(0));
|
||||
}
|
||||
|
||||
@Test
|
||||
public void whenSubListOneToTwo_thenListContainingSecondElementIsReturned() {
|
||||
List<Object> list = new CustomList<>();
|
||||
list.add("baeldung");
|
||||
list.add(".");
|
||||
list.add("com");
|
||||
List<Object> subList = list.subList(1, 2);
|
||||
|
||||
assertEquals(1, subList.size());
|
||||
assertEquals(".", subList.get(0));
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenListWithElements_whenToArray_thenArrayContainsThose() {
|
||||
List<Object> list = new CustomList<>();
|
||||
list.add("baeldung");
|
||||
list.add(".com");
|
||||
Object[] array = list.toArray();
|
||||
|
||||
assertArrayEquals(new Object[] { "baeldung", ".com" }, array);
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenListWithAnElement_whenToArray_thenInputArrayIsReturned() {
|
||||
List<Object> list = new CustomList<>();
|
||||
list.add("baeldung");
|
||||
String[] input = new String[1];
|
||||
String[] output = list.toArray(input);
|
||||
|
||||
assertArrayEquals(new String[] { "baeldung" }, input);
|
||||
}
|
||||
|
||||
@Test
|
||||
public void whenToArrayIsCalledWithEmptyInputArray_thenNewArrayIsReturned() {
|
||||
List<Object> list = new CustomList<>();
|
||||
list.add("baeldung");
|
||||
String[] input = {};
|
||||
String[] output = list.toArray(input);
|
||||
|
||||
assertArrayEquals(new String[] { "baeldung" }, output);
|
||||
}
|
||||
|
||||
@Test
|
||||
public void whenToArrayIsCalledWithLargerInput_thenOutputHasTrailingNull() {
|
||||
List<Object> list = new CustomList<>();
|
||||
list.add("baeldung");
|
||||
String[] input = new String[2];
|
||||
String[] output = list.toArray(input);
|
||||
|
||||
assertArrayEquals(new String[] { "baeldung", null }, output);
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenListWithOneElement_whenIterator_thenThisElementIsNext() {
|
||||
List<Object> list = new CustomList<>();
|
||||
list.add("baeldung");
|
||||
Iterator<Object> iterator = list.iterator();
|
||||
|
||||
assertTrue(iterator.hasNext());
|
||||
assertEquals("baeldung", iterator.next());
|
||||
}
|
||||
|
||||
@Test
|
||||
public void whenIteratorHasNextIsCalledTwice_thenTheSecondReturnsFalse() {
|
||||
List<Object> list = new CustomList<>();
|
||||
list.add("baeldung");
|
||||
Iterator<Object> iterator = list.iterator();
|
||||
|
||||
iterator.next();
|
||||
assertFalse(iterator.hasNext());
|
||||
}
|
||||
}
|
||||
@ -0,0 +1,87 @@
|
||||
package com.baeldung.java.list;
|
||||
|
||||
import static org.junit.Assert.assertEquals;
|
||||
|
||||
import java.util.Collections;
|
||||
import java.util.List;
|
||||
import java.util.ListIterator;
|
||||
|
||||
import org.apache.commons.collections4.iterators.ReverseListIterator;
|
||||
import org.apache.commons.lang3.StringUtils;
|
||||
import org.junit.jupiter.api.BeforeEach;
|
||||
import org.junit.jupiter.api.Test;
|
||||
|
||||
import com.google.common.collect.Lists;
|
||||
|
||||
public class ReverseIteratorUnitTest {
|
||||
|
||||
private final ReverseIterator reverseIterator = new ReverseIterator();
|
||||
|
||||
private List<String> list;
|
||||
|
||||
private final String originalString = "ABCDE";
|
||||
|
||||
@BeforeEach
|
||||
void setUp() {
|
||||
|
||||
list = Lists.newArrayList("A", "B", "C", "D", "E");
|
||||
}
|
||||
|
||||
@Test
|
||||
void whenIteratingUsingForLoop_thenCorrect() {
|
||||
|
||||
String reverseString = "";
|
||||
for (int i = list.size(); i-- > 0; ) {
|
||||
reverseString += list.get(i);
|
||||
}
|
||||
assertEquals(reverseString, StringUtils.reverse(originalString));
|
||||
}
|
||||
|
||||
@Test
|
||||
void whenIteratingUsingListIterator_thenCorrect() {
|
||||
|
||||
String reverseString = "";
|
||||
final ListIterator listIterator = list.listIterator(list.size());
|
||||
while (listIterator.hasPrevious()) {
|
||||
reverseString += listIterator.previous();
|
||||
}
|
||||
assertEquals(reverseString, StringUtils.reverse(originalString));
|
||||
}
|
||||
|
||||
@Test
|
||||
void whenIteratingUsingCollections_thenCorrect() {
|
||||
|
||||
String reverseString = "";
|
||||
Collections.reverse(list);
|
||||
for (final String item : list) {
|
||||
reverseString += item;
|
||||
}
|
||||
assertEquals(reverseString, StringUtils.reverse(originalString));
|
||||
|
||||
assertEquals("E", list.get(0));
|
||||
}
|
||||
|
||||
@Test
|
||||
void whenIteratingUsingApacheReverseListIterator_thenCorrect() {
|
||||
|
||||
String reverseString = "";
|
||||
final ReverseListIterator listIterator = new ReverseListIterator(list);
|
||||
while (listIterator.hasNext()) {
|
||||
reverseString += listIterator.next();
|
||||
}
|
||||
assertEquals(reverseString, StringUtils.reverse(originalString));
|
||||
}
|
||||
|
||||
@Test
|
||||
void whenIteratingUsingGuava_thenCorrect() {
|
||||
|
||||
String reverseString = "";
|
||||
final List<String> reversedList = Lists.reverse(list);
|
||||
for (final String item : reversedList) {
|
||||
reverseString += item;
|
||||
}
|
||||
assertEquals(reverseString, StringUtils.reverse(originalString));
|
||||
|
||||
assertEquals("A", list.get(0));
|
||||
}
|
||||
}
|
||||
@ -0,0 +1,51 @@
|
||||
package com.baeldung.java8;
|
||||
|
||||
import com.google.common.collect.Lists;
|
||||
import org.junit.Test;
|
||||
|
||||
import java.util.List;
|
||||
import java.util.Objects;
|
||||
import java.util.stream.Collectors;
|
||||
|
||||
import static org.hamcrest.Matchers.containsInAnyOrder;
|
||||
import static org.hamcrest.Matchers.hasSize;
|
||||
import static org.junit.Assert.assertThat;
|
||||
|
||||
public class Java8CollectionCleanupUnitTest {
|
||||
|
||||
// tests -
|
||||
|
||||
@Test
|
||||
public void givenListContainsNulls_whenFilteringParallel_thenCorrect() {
|
||||
final List<Integer> list = Lists.newArrayList(null, 1, 2, null, 3, null);
|
||||
final List<Integer> listWithoutNulls = list.parallelStream().filter(Objects::nonNull).collect(Collectors.toList());
|
||||
|
||||
assertThat(listWithoutNulls, hasSize(3));
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenListContainsNulls_whenFilteringSerial_thenCorrect() {
|
||||
final List<Integer> list = Lists.newArrayList(null, 1, 2, null, 3, null);
|
||||
final List<Integer> listWithoutNulls = list.stream().filter(Objects::nonNull).collect(Collectors.toList());
|
||||
|
||||
assertThat(listWithoutNulls, hasSize(3));
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenListContainsNulls_whenRemovingNullsWithRemoveIf_thenCorrect() {
|
||||
final List<Integer> listWithoutNulls = Lists.newArrayList(null, 1, 2, null, 3, null);
|
||||
listWithoutNulls.removeIf(Objects::isNull);
|
||||
|
||||
assertThat(listWithoutNulls, hasSize(3));
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenListContainsDuplicates_whenRemovingDuplicatesWithJava8_thenCorrect() {
|
||||
final List<Integer> listWithDuplicates = Lists.newArrayList(5, 0, 3, 1, 2, 3, 0, 0);
|
||||
final List<Integer> listWithoutDuplicates = listWithDuplicates.stream().distinct().collect(Collectors.toList());
|
||||
|
||||
assertThat(listWithoutDuplicates, hasSize(5));
|
||||
assertThat(listWithoutDuplicates, containsInAnyOrder(5, 0, 3, 1, 2));
|
||||
}
|
||||
|
||||
}
|
||||
@ -0,0 +1,74 @@
|
||||
package com.baeldung.java8;
|
||||
|
||||
import com.baeldung.java_8_features.Car;
|
||||
import com.baeldung.java_8_features.Person;
|
||||
|
||||
import org.junit.Test;
|
||||
|
||||
import java.util.Arrays;
|
||||
import java.util.Comparator;
|
||||
import java.util.List;
|
||||
import java.util.NoSuchElementException;
|
||||
|
||||
import static org.junit.Assert.assertEquals;
|
||||
|
||||
public class Java8MaxMinUnitTest {
|
||||
|
||||
@Test
|
||||
public void whenListIsOfIntegerThenMaxCanBeDoneUsingIntegerComparator() {
|
||||
//given
|
||||
final List<Integer> listOfIntegers = Arrays.asList(1, 2, 3, 4, 56, 7, 89, 10);
|
||||
final Integer expectedResult = 89;
|
||||
|
||||
//then
|
||||
final Integer max = listOfIntegers
|
||||
.stream()
|
||||
.mapToInt(v -> v)
|
||||
.max().orElseThrow(NoSuchElementException::new);
|
||||
|
||||
assertEquals("Should be 89", expectedResult, max);
|
||||
}
|
||||
|
||||
@Test
|
||||
public void whenListIsOfPersonObjectThenMinCanBeDoneUsingCustomComparatorThroughLambda() {
|
||||
//given
|
||||
final Person alex = new Person("Alex", 23);
|
||||
final Person john = new Person("John", 40);
|
||||
final Person peter = new Person("Peter", 32);
|
||||
final List<Person> people = Arrays.asList(alex, john, peter);
|
||||
|
||||
//then
|
||||
final Person minByAge = people
|
||||
.stream()
|
||||
.min(Comparator.comparing(Person::getAge))
|
||||
.orElseThrow(NoSuchElementException::new);
|
||||
|
||||
assertEquals("Should be Alex", alex, minByAge);
|
||||
}
|
||||
|
||||
@Test
|
||||
public void whenArrayIsOfIntegerThenMinUsesIntegerComparator() {
|
||||
int[] integers = new int[] { 20, 98, 12, 7, 35 };
|
||||
|
||||
int min = Arrays.stream(integers)
|
||||
.min()
|
||||
.getAsInt();
|
||||
|
||||
assertEquals(7, min);
|
||||
}
|
||||
|
||||
@Test
|
||||
public void whenArrayIsOfCustomTypeThenMaxUsesCustomComparator() {
|
||||
final Car porsche = new Car("Porsche 959", 319);
|
||||
final Car ferrari = new Car("Ferrari 288 GTO", 303);
|
||||
final Car bugatti = new Car("Bugatti Veyron 16.4 Super Sport", 415);
|
||||
final Car mcLaren = new Car("McLaren F1", 355);
|
||||
final Car[] fastCars = { porsche, ferrari, bugatti, mcLaren };
|
||||
|
||||
final Car maxBySpeed = Arrays.stream(fastCars)
|
||||
.max(Comparator.comparing(Car::getTopSpeed))
|
||||
.orElseThrow(NoSuchElementException::new);
|
||||
|
||||
assertEquals(bugatti, maxBySpeed);
|
||||
}
|
||||
}
|
||||
@ -0,0 +1,87 @@
|
||||
package com.baeldung.list;
|
||||
|
||||
import org.junit.Assert;
|
||||
import org.junit.Before;
|
||||
import org.junit.Test;
|
||||
|
||||
import java.util.*;
|
||||
|
||||
import static org.junit.Assert.*;
|
||||
|
||||
public class AddElementsUnitTest {
|
||||
|
||||
List<Flower> flowers;
|
||||
|
||||
@Before
|
||||
public void init() {
|
||||
this.flowers = new ArrayList<>(Arrays.asList(
|
||||
new Flower("Poppy", 12),
|
||||
new Flower("Anemone", 8),
|
||||
new Flower("Catmint", 12)));
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenAList_whenTargetListIsEmpty_thenReturnTargetListWithNewItems() {
|
||||
List<Flower> anotherList = new ArrayList<>();
|
||||
anotherList.addAll(flowers);
|
||||
|
||||
assertEquals(anotherList.size(), flowers.size());
|
||||
Assert.assertTrue(anotherList.containsAll(flowers));
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenAList_whenTargetListIsEmpty_thenReturnTargetListWithOneModifiedElementByConstructor() {
|
||||
List<Flower> anotherList = new ArrayList<>();
|
||||
anotherList.addAll(flowers);
|
||||
|
||||
Flower flower = anotherList.get(0);
|
||||
flower.setPetals(flowers.get(0).getPetals() * 3);
|
||||
|
||||
assertEquals(anotherList.size(), flowers.size());
|
||||
Assert.assertTrue(anotherList.containsAll(flowers));
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenAListAndElements_whenUseCollectionsAddAll_thenAddElementsToTargetList() {
|
||||
List<Flower> target = new ArrayList<>();
|
||||
|
||||
Collections.addAll(target, flowers.get(0), flowers.get(1), flowers.get(2), flowers.get(0));
|
||||
|
||||
assertEquals(target.size(), 4);
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenTwoList_whenSourceListDoesNotHaveNullElements_thenAddElementsToTargetListSkipFirstElementByStreamProcess() {
|
||||
List<Flower> flowerVase = new ArrayList<>();
|
||||
|
||||
flowers.stream()
|
||||
.skip(1)
|
||||
.forEachOrdered(flowerVase::add);
|
||||
|
||||
assertEquals(flowerVase.size() + 1, flowers.size());
|
||||
assertFalse(flowerVase.containsAll(flowers));
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenTwoList_whenSourceListDoesNotHaveNullElements_thenAddElementsToTargetListFilteringElementsByStreamProcess() {
|
||||
List<Flower> flowerVase = new ArrayList<>();
|
||||
|
||||
flowers.stream()
|
||||
.filter(f -> f.getPetals() > 10)
|
||||
.forEachOrdered(flowerVase::add);
|
||||
|
||||
assertEquals(flowerVase.size() + 1, flowers.size());
|
||||
assertFalse(flowerVase.containsAll(flowers));
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenAList_whenListIsNotNull_thenAddElementsToListByStreamProcessWihtOptional() {
|
||||
List<Flower> target = new ArrayList<>();
|
||||
|
||||
Optional.ofNullable(flowers)
|
||||
.ifPresent(target::addAll);
|
||||
|
||||
assertNotNull(target);
|
||||
assertEquals(target.size(), 3);
|
||||
}
|
||||
}
|
||||
@ -0,0 +1,69 @@
|
||||
package com.baeldung.list.listoflist;
|
||||
|
||||
import org.junit.Before;
|
||||
import org.junit.Test;
|
||||
|
||||
import java.util.ArrayList;
|
||||
import java.util.List;
|
||||
|
||||
import static org.junit.Assert.assertEquals;
|
||||
|
||||
public class ListOfListsUnitTest {
|
||||
|
||||
private List<List<? extends Stationery>> listOfLists = new ArrayList<>();
|
||||
private List<Pen> penList = new ArrayList<>();
|
||||
private List<Pencil> pencilList = new ArrayList<>();
|
||||
private List<Rubber> rubberList = new ArrayList<>();
|
||||
|
||||
@SuppressWarnings("unchecked")
|
||||
@Before
|
||||
public void init() {
|
||||
listOfLists.add(penList);
|
||||
listOfLists.add(pencilList);
|
||||
listOfLists.add(rubberList);
|
||||
|
||||
((ArrayList<Pen>) listOfLists.get(0)).add(new Pen("Pen 1"));
|
||||
((ArrayList<Pencil>) listOfLists.get(1)).add(new Pencil("Pencil 1"));
|
||||
((ArrayList<Rubber>) listOfLists.get(2)).add(new Rubber("Rubber 1"));
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenListOfLists_thenCheckNames() {
|
||||
assertEquals("Pen 1", ((Pen) listOfLists.get(0).get(0)).getName());
|
||||
assertEquals("Pencil 1", ((Pencil) listOfLists.get(1).get(0)).getName());
|
||||
assertEquals("Rubber 1", ((Rubber) listOfLists.get(2).get(0)).getName());
|
||||
}
|
||||
|
||||
@SuppressWarnings("unchecked")
|
||||
@Test
|
||||
public void givenListOfLists_whenRemovingElements_thenCheckNames() {
|
||||
|
||||
((ArrayList<Pencil>) listOfLists.get(1)).remove(0);
|
||||
listOfLists.remove(1);
|
||||
assertEquals("Rubber 1", ((Rubber) listOfLists.get(1).get(0)).getName());
|
||||
listOfLists.remove(0);
|
||||
assertEquals("Rubber 1", ((Rubber) listOfLists.get(0).get(0)).getName());
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenThreeList_whenCombineIntoOneList_thenCheckList() {
|
||||
ArrayList<Pen> pens = new ArrayList<>();
|
||||
pens.add(new Pen("Pen 1"));
|
||||
pens.add(new Pen("Pen 2"));
|
||||
ArrayList<Pencil> pencils = new ArrayList<>();
|
||||
pencils.add(new Pencil("Pencil 1"));
|
||||
pencils.add(new Pencil("Pencil 2"));
|
||||
ArrayList<Rubber> rubbers = new ArrayList<>();
|
||||
rubbers.add(new Rubber("Rubber 1"));
|
||||
rubbers.add(new Rubber("Rubber 2"));
|
||||
|
||||
List<ArrayList<? extends Stationery>> list = new ArrayList<ArrayList<? extends Stationery>>();
|
||||
list.add(pens);
|
||||
list.add(pencils);
|
||||
list.add(rubbers);
|
||||
|
||||
assertEquals("Pen 1", ((Pen) list.get(0).get(0)).getName());
|
||||
assertEquals("Pencil 1", ((Pencil) list.get(1).get(0)).getName());
|
||||
assertEquals("Rubber 1", ((Rubber) list.get(2).get(0)).getName());
|
||||
}
|
||||
}
|
||||
@ -0,0 +1,71 @@
|
||||
package com.baeldung.list.random;
|
||||
|
||||
import com.google.common.collect.Lists;
|
||||
import org.junit.Test;
|
||||
|
||||
import java.util.*;
|
||||
import java.util.concurrent.ThreadLocalRandom;
|
||||
|
||||
public class RandomListElementUnitTest {
|
||||
|
||||
@Test
|
||||
public void givenList_whenRandomIndexChosen_shouldReturnARandomElementUsingRandom() {
|
||||
List<Integer> givenList = Lists.newArrayList(1, 2, 3);
|
||||
Random rand = new Random();
|
||||
|
||||
givenList.get(rand.nextInt(givenList.size()));
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenList_whenRandomIndexChosen_shouldReturnARandomElementUsingMathRandom() {
|
||||
List<Integer> givenList = Lists.newArrayList(1, 2, 3);
|
||||
|
||||
givenList.get((int) (Math.random() * givenList.size()));
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenList_whenNumberElementsChosen_shouldReturnRandomElementsRepeat() {
|
||||
Random rand = new Random();
|
||||
List<String> givenList = Lists.newArrayList("one", "two", "three", "four");
|
||||
|
||||
int numberOfElements = 2;
|
||||
|
||||
for (int i = 0; i < numberOfElements; i++) {
|
||||
int randomIndex = rand.nextInt(givenList.size());
|
||||
givenList.get(randomIndex);
|
||||
}
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenList_whenNumberElementsChosen_shouldReturnRandomElementsNoRepeat() {
|
||||
Random rand = new Random();
|
||||
List<String> givenList = Lists.newArrayList("one", "two", "three", "four");
|
||||
|
||||
int numberOfElements = 2;
|
||||
|
||||
for (int i = 0; i < numberOfElements; i++) {
|
||||
int randomIndex = rand.nextInt(givenList.size());
|
||||
givenList.get(randomIndex);
|
||||
givenList.remove(randomIndex);
|
||||
}
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenList_whenSeriesLengthChosen_shouldReturnRandomSeries() {
|
||||
List<Integer> givenList = Lists.newArrayList(1, 2, 3, 4, 5, 6);
|
||||
Collections.shuffle(givenList);
|
||||
|
||||
int randomSeriesLength = 3;
|
||||
|
||||
givenList.subList(0, randomSeriesLength - 1);
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenList_whenRandomIndexChosen_shouldReturnElementThreadSafely() {
|
||||
List<Integer> givenList = Lists.newArrayList(1, 2, 3, 4, 5, 6);
|
||||
int randomIndex = ThreadLocalRandom.current().nextInt(10) % givenList.size();
|
||||
|
||||
givenList.get(randomIndex);
|
||||
}
|
||||
|
||||
}
|
||||
@ -0,0 +1,212 @@
|
||||
package com.baeldung.list.removeall;
|
||||
|
||||
import static com.baeldung.list.removeall.RemoveAll.removeWithCallingRemoveUntilModifies;
|
||||
import static com.baeldung.list.removeall.RemoveAll.removeWithCollectingAndReturningRemainingElements;
|
||||
import static com.baeldung.list.removeall.RemoveAll.removeWithCollectingRemainingElementsAndAddingToOriginalList;
|
||||
import static com.baeldung.list.removeall.RemoveAll.removeWithForEachLoop;
|
||||
import static com.baeldung.list.removeall.RemoveAll.removeWithForLoopDecrementOnRemove;
|
||||
import static com.baeldung.list.removeall.RemoveAll.removeWithForLoopIncrementIfRemains;
|
||||
import static com.baeldung.list.removeall.RemoveAll.removeWithIterator;
|
||||
import static com.baeldung.list.removeall.RemoveAll.removeWithRemoveIf;
|
||||
import static com.baeldung.list.removeall.RemoveAll.removeWithStandardForLoopUsingIndex;
|
||||
import static com.baeldung.list.removeall.RemoveAll.removeWithStreamFilter;
|
||||
import static com.baeldung.list.removeall.RemoveAll.removeWithWhileLoopNonPrimitiveElement;
|
||||
import static com.baeldung.list.removeall.RemoveAll.removeWithWhileLoopPrimitiveElement;
|
||||
import static com.baeldung.list.removeall.RemoveAll.removeWithWhileLoopStoringFirstOccurrenceIndex;
|
||||
import static org.assertj.core.api.Assertions.assertThat;
|
||||
import static org.assertj.core.api.Assertions.assertThatThrownBy;
|
||||
|
||||
import java.util.ArrayList;
|
||||
import java.util.Arrays;
|
||||
import java.util.ConcurrentModificationException;
|
||||
import java.util.List;
|
||||
|
||||
import org.junit.jupiter.api.Test;
|
||||
import org.junit.jupiter.api.TestInstance;
|
||||
|
||||
@TestInstance(TestInstance.Lifecycle.PER_CLASS)
|
||||
public class RemoveAllUnitTest {
|
||||
|
||||
private List<Integer> list(Integer... elements) {
|
||||
return new ArrayList<>(Arrays.asList(elements));
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenAList_whenRemovingElementsWithWhileLoopUsingPrimitiveElement_thenTheResultCorrect() {
|
||||
// given
|
||||
List<Integer> list = list(1, 2, 3);
|
||||
int valueToRemove = 1;
|
||||
|
||||
// when
|
||||
assertThatThrownBy(() -> removeWithWhileLoopPrimitiveElement(list, valueToRemove))
|
||||
.isInstanceOf(IndexOutOfBoundsException.class);
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenAList_whenRemovingElementsWithWhileLoopUsingNonPrimitiveElement_thenTheResultCorrect() {
|
||||
// given
|
||||
List<Integer> list = list(1, 2, 3);
|
||||
int valueToRemove = 1;
|
||||
|
||||
// when
|
||||
removeWithWhileLoopNonPrimitiveElement(list, valueToRemove);
|
||||
|
||||
// then
|
||||
assertThat(list).isEqualTo(list(2, 3));
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenAList_whenRemovingElementsWithWhileLoopStoringFirstOccurrenceIndex_thenTheResultCorrect() {
|
||||
// given
|
||||
List<Integer> list = list(1, 2, 3);
|
||||
int valueToRemove = 1;
|
||||
|
||||
// when
|
||||
removeWithWhileLoopStoringFirstOccurrenceIndex(list, valueToRemove);
|
||||
|
||||
// then
|
||||
assertThat(list).isEqualTo(list(2, 3));
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenAList_whenRemovingElementsWithCallingRemoveUntilModifies_thenTheResultIsCorrect() {
|
||||
// given
|
||||
List<Integer> list = list(1, 1, 2, 3);
|
||||
int valueToRemove = 1;
|
||||
|
||||
// when
|
||||
removeWithCallingRemoveUntilModifies(list, valueToRemove);
|
||||
|
||||
// then
|
||||
assertThat(list).isEqualTo(list(2, 3));
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenAListWithoutDuplication_whenRemovingElementsWithStandardForLoopUsingIndex_thenTheResultIsCorrect() {
|
||||
// given
|
||||
List<Integer> list = list(1, 2, 3);
|
||||
int valueToRemove = 1;
|
||||
|
||||
// when
|
||||
removeWithStandardForLoopUsingIndex(list, valueToRemove);
|
||||
|
||||
// then
|
||||
assertThat(list).isEqualTo(list(2, 3));
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenAListWithAdjacentElements_whenRemovingElementsWithStandardForLoop_thenTheResultIsInCorrect() {
|
||||
// given
|
||||
List<Integer> list = list(1, 1, 2, 3);
|
||||
int valueToRemove = 1;
|
||||
|
||||
// when
|
||||
removeWithStandardForLoopUsingIndex(list, valueToRemove);
|
||||
|
||||
// then
|
||||
assertThat(list).isEqualTo(list(1, 2, 3));
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenAListWithAdjacentElements_whenRemovingElementsWithForLoopAndDecrementOnRemove_thenTheResultIsCorrect() {
|
||||
// given
|
||||
List<Integer> list = list(1, 1, 2, 3);
|
||||
int valueToRemove = 1;
|
||||
|
||||
// when
|
||||
removeWithForLoopDecrementOnRemove(list, valueToRemove);
|
||||
|
||||
// then
|
||||
assertThat(list).isEqualTo(list(2, 3));
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenAListWithAdjacentElements_whenRemovingElementsWithForLoopAndIncrementIfRemains_thenTheResultIsCorrect() {
|
||||
// given
|
||||
List<Integer> list = list(1, 1, 2, 3);
|
||||
int valueToRemove = 1;
|
||||
|
||||
// when
|
||||
removeWithForLoopIncrementIfRemains(list, valueToRemove);
|
||||
|
||||
// then
|
||||
assertThat(list).isEqualTo(list(2, 3));
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenAList_whenRemovingElementsWithForEachLoop_thenExceptionIsThrown() {
|
||||
// given
|
||||
List<Integer> list = list(1, 1, 2, 3);
|
||||
int valueToRemove = 1;
|
||||
|
||||
// when
|
||||
assertThatThrownBy(() -> removeWithForEachLoop(list, valueToRemove))
|
||||
.isInstanceOf(ConcurrentModificationException.class);
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenAList_whenRemovingElementsWithIterator_thenTheResultIsCorrect() {
|
||||
// given
|
||||
List<Integer> list = list(1, 1, 2, 3);
|
||||
int valueToRemove = 1;
|
||||
|
||||
// when
|
||||
removeWithIterator(list, valueToRemove);
|
||||
|
||||
// then
|
||||
assertThat(list).isEqualTo(list(2, 3));
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenAList_whenRemovingElementsWithCollectingAndReturningRemainingElements_thenTheResultIsCorrect() {
|
||||
// given
|
||||
List<Integer> list = list(1, 1, 2, 3);
|
||||
int valueToRemove = 1;
|
||||
|
||||
// when
|
||||
List<Integer> result = removeWithCollectingAndReturningRemainingElements(list, valueToRemove);
|
||||
|
||||
// then
|
||||
assertThat(result).isEqualTo(list(2, 3));
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenAList_whenRemovingElementsWithCollectingRemainingAndAddingToOriginalList_thenTheResultIsCorrect() {
|
||||
// given
|
||||
List<Integer> list = list(1, 1, 2, 3);
|
||||
int valueToRemove = 1;
|
||||
|
||||
// when
|
||||
removeWithCollectingRemainingElementsAndAddingToOriginalList(list, valueToRemove);
|
||||
|
||||
// then
|
||||
assertThat(list).isEqualTo(list(2, 3));
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenAList_whenRemovingElementsWithStreamFilter_thenTheResultIsCorrect() {
|
||||
// given
|
||||
List<Integer> list = list(1, 1, 2, 3);
|
||||
int valueToRemove = 1;
|
||||
|
||||
// when
|
||||
List<Integer> result = removeWithStreamFilter(list, valueToRemove);
|
||||
|
||||
// then
|
||||
assertThat(result).isEqualTo(list(2, 3));
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenAList_whenRemovingElementsWithCallingRemoveIf_thenTheResultIsCorrect() {
|
||||
// given
|
||||
List<Integer> list = list(1, 1, 2, 3);
|
||||
int valueToRemove = 1;
|
||||
|
||||
// when
|
||||
removeWithRemoveIf(list, valueToRemove);
|
||||
|
||||
// then
|
||||
assertThat(list).isEqualTo(list(2, 3));
|
||||
}
|
||||
|
||||
}
|
||||
Loading…
x
Reference in New Issue
Block a user