BAEL-1584 : Finding an element in list (#4067)
* BAEL-1584 : Find an Element in Given List
This commit is contained in:
Shubhra Srivastava
Josh Cummings
parent
47a7aaae5d
commit
b559157482
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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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@ -0,0 +1,77 @@
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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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@ -1,71 +0,0 @@
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package com.baeldung.findanelement;
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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.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 FindElementInAList<T> {
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public T findUsingIndexOf(T element, List<T> list) {
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int index = list.indexOf(element);
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if (index >= 0) {
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return element;
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}
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return null;
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}
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public boolean findUsingListIterator(T element, List<T> list) {
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ListIterator<T> listIterator = list.listIterator();
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while (listIterator.hasNext()) {
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T elementFromList = listIterator.next();
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if (elementFromList.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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public boolean findUsingEnhancedForLoop(T element, List<T> list) {
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for (T elementFromList : list) {
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if (element.equals(elementFromList)) {
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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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public T findUsingStream(T element, List<T> list) {
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return list.stream()
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.filter(integer -> integer.equals(element))
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.findFirst()
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.orElse(null);
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}
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public T findUsingParallelStream(T element, List<T> list) {
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return list.parallelStream()
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.filter(integer -> integer.equals(element))
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.findAny()
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.orElse(null);
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}
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public T findUsingGuava(T element, List<T> list) {
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T foundElement = Iterables.tryFind(list, new Predicate<T>() {
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public boolean apply(T input) {
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return element.equals(input);
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}
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}).orNull();
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return foundElement;
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}
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public T findUsingApacheCommon(T element, List<T> list) {
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T foundElement = IterableUtils.find(list, new org.apache.commons.collections4.Predicate<T>() {
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public boolean evaluate(T input) {
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return element.equals(input);
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}
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});
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return foundElement;
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}
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}
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@ -0,0 +1,158 @@
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package com.baeldung.findanelement;
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import static org.junit.Assert.*;
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import java.util.ArrayList;
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import java.util.List;
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import org.junit.Test;
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public class FindACustomerInGivenListTest {
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private static List<Customer> customers = new ArrayList<>();
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static {
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customers.add(new Customer(1, "Jack"));
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customers.add(new Customer(2, "James"));
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customers.add(new Customer(3, "Sam"));
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}
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private static FindACustomerInGivenList findACustomerInGivenList = new FindACustomerInGivenList();
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@Test
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public void givenAnIndex_whenFoundUsingGivenIndex_thenReturnCustomer() {
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Customer customer = findACustomerInGivenList.findUsingGivenIndex(0, customers);
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assertEquals(1, customer.getId());
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}
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@Test
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public void givenAnIndex_whenNotFoundUsingGivenIndex_thenReturnNull() {
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Customer customer = findACustomerInGivenList.findUsingGivenIndex(5, customers);
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assertNull(customer);
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}
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@Test
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public void givenACustomer_whenFoundUsingContains_thenReturnTrue() {
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Customer james = new Customer(2, "James");
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boolean isJamesPresent = findACustomerInGivenList.findUsingContains(james, customers);
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assertEquals(true, isJamesPresent);
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}
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@Test
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public void givenACustomer_whenNotFoundUsingContains_thenReturnFalse() {
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Customer john = new Customer(5, "John");
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boolean isJohnPresent = findACustomerInGivenList.findUsingContains(john, customers);
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assertEquals(false, isJohnPresent);
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}
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@Test
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public void givenACustomer_whenFoundUsingIndexOf_thenReturnItsIndex() {
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Customer james = new Customer(2, "James");
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int indexOfJames = findACustomerInGivenList.findUsingIndexOf(james, customers);
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assertEquals(1, indexOfJames);
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}
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@Test
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public void givenACustomer_whenNotFoundUsingIndexOf_thenReturnMinus1() {
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Customer john = new Customer(5, "John");
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int indexOfJohn = findACustomerInGivenList.findUsingIndexOf(john, customers);
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assertEquals(-1, indexOfJohn);
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}
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@Test
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public void givenName_whenCustomerWithNameFoundUsingIterator_thenReturnCustomer() {
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Customer james = findACustomerInGivenList.findUsingIterator("James", customers);
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assertEquals("James", james.getName());
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assertEquals(2, james.getId());
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}
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@Test
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public void givenName_whenCustomerWithNameNotFoundUsingIterator_thenReturnNull() {
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Customer john = findACustomerInGivenList.findUsingIterator("John", customers);
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assertNull(john);
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}
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@Test
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public void givenName_whenCustomerWithNameFoundUsingEnhancedFor_thenReturnCustomer() {
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Customer james = findACustomerInGivenList.findUsingEnhancedForLoop("James", customers);
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assertEquals("James", james.getName());
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assertEquals(2, james.getId());
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}
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@Test
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public void givenName_whenCustomerWithNameNotFoundUsingEnhancedFor_thenReturnNull() {
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Customer john = findACustomerInGivenList.findUsingEnhancedForLoop("John", customers);
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assertNull(john);
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}
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@Test
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public void givenName_whenCustomerWithNameFoundUsingStream_thenReturnCustomer() {
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Customer james = findACustomerInGivenList.findUsingStream("James", customers);
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assertEquals("James", james.getName());
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assertEquals(2, james.getId());
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}
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@Test
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public void givenName_whenCustomerWithNameNotFoundUsingStream_thenReturnNull() {
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Customer john = findACustomerInGivenList.findUsingStream("John", customers);
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assertNull(john);
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}
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@Test
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public void givenName_whenCustomerWithNameFoundUsingParallelStream_thenReturnCustomer() {
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Customer james = findACustomerInGivenList.findUsingParallelStream("James", customers);
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assertEquals("James", james.getName());
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assertEquals(2, james.getId());
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}
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@Test
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public void givenName_whenCustomerWithNameNotFoundUsingParallelStream_thenReturnNull() {
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Customer john = findACustomerInGivenList.findUsingParallelStream("John", customers);
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assertNull(john);
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}
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@Test
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public void givenName_whenCustomerWithNameFoundUsingApacheCommon_thenReturnCustomer() {
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Customer james = findACustomerInGivenList.findUsingApacheCommon("James", customers);
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assertEquals("James", james.getName());
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assertEquals(2, james.getId());
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}
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@Test
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public void givenName_whenCustomerWithNameNotFoundUsingApacheCommon_thenReturnNull() {
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Customer john = findACustomerInGivenList.findUsingApacheCommon("John", customers);
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assertNull(john);
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}
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@Test
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public void givenName_whenCustomerWithNameFoundUsingGuava_thenReturnCustomer() {
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Customer james = findACustomerInGivenList.findUsingGuava("James", customers);
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assertEquals("James", james.getName());
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assertEquals(2, james.getId());
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}
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@Test
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public void givenName_whenCustomerWithNameNotFoundUsingGuava_thenReturnNull() {
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Customer john = findACustomerInGivenList.findUsingGuava("John", customers);
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assertNull(john);
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}
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}
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@ -1,116 +0,0 @@
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package com.baeldung.findanelement;
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import static org.junit.Assert.assertNull;
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import static org.junit.Assert.assertTrue;
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import java.util.ArrayList;
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import java.util.List;
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import org.junit.Test;
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public class FindAnElementTest {
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private static List<Integer> scores = new ArrayList<>();
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static {
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scores.add(0);
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scores.add(1);
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scores.add(2);
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}
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private static FindElementInAList<Integer> findElementInAList = new FindElementInAList<>();
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@Test
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public void givenElement_whenFoundUsingIndexOf_thenReturnElement() {
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Integer scoreToFind = 1;
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Integer score = findElementInAList.findUsingIndexOf(scoreToFind, scores);
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assertTrue(score.equals(scoreToFind));
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}
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@Test
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public void givenElement_whenNotFoundUsingListIterator_thenReturnNull() {
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boolean found = findElementInAList.findUsingListIterator(5, scores);
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assertTrue(!found);
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}
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@Test
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public void givenElement_whenFoundListIterator_thenReturnElement() {
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Integer scoreToFind = 1;
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boolean found = findElementInAList.findUsingListIterator(scoreToFind, scores);
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assertTrue(found);
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}
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@Test
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public void givenElement_whenNotFoundUsingIndexOf_thenReturnNull() {
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Integer score = findElementInAList.findUsingIndexOf(5, scores);
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assertNull(score);
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}
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@Test
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public void givenElement_whenFoundUsingEnhancedForLoop_thenReturnElement() {
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Integer scoreToFind = 1;
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boolean found = findElementInAList.findUsingEnhancedForLoop(scoreToFind, scores);
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assertTrue(found);
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}
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@Test
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public void givenElement_whenNotFoundUsingEnhancedForLoop_thenReturnNull() {
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Integer scoreToFind = 5;
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boolean found = findElementInAList.findUsingEnhancedForLoop(scoreToFind, scores);
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assertTrue(!found);
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}
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@Test
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public void givenElement_whenFoundUsingStream_thenReturnElement() {
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Integer scoreToFind = 1;
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Integer score = findElementInAList.findUsingStream(scoreToFind, scores);
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assertTrue(score.equals(scoreToFind));
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}
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@Test
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public void givenElement_whenNotFoundUsingStream_thenReturnNull() {
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Integer scoreToFind = 5;
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Integer score = findElementInAList.findUsingStream(scoreToFind, scores);
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assertNull(score);
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}
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@Test
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public void givenElement_whenFoundUsingParallelStream_thenReturnElement() {
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Integer scoreToFind = 1;
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Integer score = findElementInAList.findUsingParallelStream(scoreToFind, scores);
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assertTrue(score.equals(scoreToFind));
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}
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@Test
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public void givenElement_whenNotFoundUsingParallelStream_thenReturnNull() {
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Integer scoreToFind = 5;
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Integer score = findElementInAList.findUsingParallelStream(scoreToFind, scores);
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assertNull(score);
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}
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@Test
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public void givenElement_whenFoundUsingGuava_thenReturnElement() {
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Integer scoreToFind = 1;
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Integer score = findElementInAList.findUsingGuava(scoreToFind, scores);
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assertTrue(score.equals(scoreToFind));
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}
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@Test
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public void givenElement_whenNotFoundUsingGuava_thenReturnNull() {
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Integer scoreToFind = 5;
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Integer score = findElementInAList.findUsingGuava(scoreToFind, scores);
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assertNull(score);
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}
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@Test
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public void givenElement_whenFoundUsingApacheCommons_thenReturnElement() {
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Integer scoreToFind = 1;
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Integer score = findElementInAList.findUsingApacheCommon(scoreToFind, scores);
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assertTrue(score.equals(scoreToFind));
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}
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@Test
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public void givenElement_whenNotFoundUsingApacheCommons_thenReturnNull() {
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Integer scoreToFind = 5;
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Integer score = findElementInAList.findUsingApacheCommon(scoreToFind, scores);
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assertNull(score);
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}
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}
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