[BAEL-6339] custom iterator with testcases (#14038)
Co-authored-by: Bhaskar <bhaskar.dastidar@freshworks.com>
This commit is contained in:
Bhaskar Ghosh Dastidar
GitHub
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06bf1155e8
commit
da265d4f81
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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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<project xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
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xmlns="http://maven.apache.org/POM/4.0.0"
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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-5</artifactId>
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<name>core-java-collections-5</name>
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<build>
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<plugins>
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<plugin>
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<groupId>org.apache.maven.plugins</groupId>
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<artifactId>maven-compiler-plugin</artifactId>
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<configuration>
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<source>9</source>
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<target>9</target>
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</configuration>
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</plugin>
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</plugins>
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</build>
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<packaging>jar</packaging>
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<parent>
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package com.baeldung.customiterators;
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import java.util.Iterator;
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import java.util.List;
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import java.util.NoSuchElementException;
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public class CustomMovieIterator implements Iterator<Movie> {
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private int currentIndex;
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private final List<Movie> list;
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public CustomMovieIterator(List<Movie> list) {
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this.list = list;
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this.currentIndex = 0;
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}
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@Override
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public boolean hasNext() {
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while (currentIndex < list.size()) {
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Movie currentMovie = list.get(currentIndex);
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if (isMovieEligible(currentMovie)) {
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return true;
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}
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currentIndex++;
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}
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return false;
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}
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@Override
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public Movie next() {
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if (!hasNext()) {
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throw new NoSuchElementException();
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}
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return list.get(currentIndex++);
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}
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private boolean isMovieEligible(Movie movie) {
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return movie.getRating() >= 8;
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}
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}
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@ -0,0 +1,37 @@
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package com.baeldung.customiterators;
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public class Movie {
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private String name;
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private String director;
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private float rating;
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public Movie(String name, String director, float rating) {
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this.name = name;
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this.director = director;
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this.rating = rating;
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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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public void setName(String name) {
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this.name = name;
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}
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public String getDirector() {
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return director;
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}
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public void setDirector(String director) {
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this.director = director;
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}
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public float getRating() {
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return rating;
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}
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public void setRating(float rating) {
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this.rating = rating;
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}
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}
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@ -0,0 +1,139 @@
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package com.baeldung.customiterators;
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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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/**
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* Please note that this class has been added for representation purposes of how a custom collection and its iterator would be.
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* This does not have working code.
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*/
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public class MyList<E> implements List<E> {
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@Override
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public int size() {
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return 0;
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}
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@Override
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public boolean isEmpty() {
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return false;
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}
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@Override
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public boolean contains(Object o) {
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return false;
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}
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@Override
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public boolean add(E e) {
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return false;
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}
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@Override
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public boolean remove(Object o) {
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return false;
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}
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@Override
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public Iterator<E> iterator() {
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return new MyListIterator();
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}
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private class MyListIterator implements Iterator<E> {
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@Override
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public boolean hasNext() {
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return false;
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}
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@Override
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public E next() {
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return null;
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}
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}
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@Override
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public Object[] toArray() {
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return new Object[0];
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}
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@Override
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public <T> T[] toArray(T[] a) {
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return null;
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}
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@Override
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public boolean containsAll(Collection<?> c) {
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return false;
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}
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@Override
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public boolean addAll(Collection<? extends E> c) {
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return false;
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}
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@Override
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public boolean addAll(int index, Collection<? extends E> c) {
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return false;
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}
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@Override
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public boolean removeAll(Collection<?> c) {
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return false;
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}
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@Override
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public boolean retainAll(Collection<?> c) {
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return false;
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}
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@Override
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public void clear() {
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}
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@Override
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public E get(int index) {
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return null;
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}
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@Override
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public E set(int index, E element) {
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return null;
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}
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@Override
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public void add(int index, E element) {
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}
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@Override
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public E remove(int index) {
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return null;
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}
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@Override
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public int indexOf(Object o) {
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return 0;
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}
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@Override
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public int lastIndexOf(Object o) {
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return 0;
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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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return null;
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}
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@Override
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public List<E> subList(int fromIndex, int toIndex) {
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return null;
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}
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}
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@ -0,0 +1,44 @@
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package com.baeldung.customiterators;
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import java.util.Iterator;
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import java.util.List;
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import java.util.NoSuchElementException;
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public class PalindromIterator implements Iterator<String> {
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private final List<String> list;
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private int currentIndex;
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public PalindromIterator(List<String> list) {
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this.list = list;
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this.currentIndex = 0;
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}
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@Override
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public boolean hasNext() {
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while (currentIndex < list.size()) {
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String currString = list.get(currentIndex);
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if (isPalindrome(currString)) {
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return true;
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}
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currentIndex++;
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}
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return false;
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}
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@Override
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public String next() {
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if (!hasNext()) {
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throw new NoSuchElementException();
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}
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return list.get(currentIndex++);
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}
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private boolean isPalindrome(String input) {
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for (int i = 0; i < input.length() / 2; i++) {
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if (input.charAt(i) != input.charAt(input.length() - i - 1)) {
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return false;
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}
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}
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return true;
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}
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}
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@ -0,0 +1,53 @@
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package com.baeldung.customiterators;
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import static org.junit.Assert.assertEquals;
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import java.util.Iterator;
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import java.util.List;
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import org.junit.Assert;
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import org.junit.Test;
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public class IteratorsUnitTest {
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@Test
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public void givenListOfStrings_whenIteratedWithDefaultIterator() {
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List<String> listOfStrings = List.of("hello", "world", "this", "is", "a", "test");
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Iterator<String> iterator = listOfStrings.iterator();
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Assert.assertTrue(iterator.hasNext());
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assertEquals(iterator.next(), "hello");
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}
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@Test
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public void givenListOfStrings_whenPalindromIterator_thenOnlyPalindromes() {
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List<String> listOfStrings = List.of("oslo", "madam", "car", "deed", "wow", "test");
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PalindromIterator palindromIterator = new PalindromIterator(listOfStrings);
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int count = 0;
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while (palindromIterator.hasNext()) {
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palindromIterator.next();
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count++;
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}
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assertEquals(count, 3);
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}
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@Test
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public void givenMovieList_whenMovieIteratorUsed_thenOnlyHighRatedMovies() {
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List<Movie> movies = getMovies();
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CustomMovieIterator movieIterator = new CustomMovieIterator(movies);
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int count = 0;
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while (movieIterator.hasNext()) {
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movieIterator.next();
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count++;
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}
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assertEquals(4, movies.size());
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assertEquals(2, count);
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}
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private List<Movie> getMovies() {
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Movie movie1 = new Movie("The Dark Knight", "Nolan", 10);
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Movie movie2 = new Movie("Avatar", "Cameron", 9);
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Movie movie3 = new Movie("Tenet", "Nolan", 7);
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Movie movie4 = new Movie("Extraction", "Hargrave", 5);
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return List.of(movie1, movie2, movie3, movie4);
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}
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}
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