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Rajeev Kumar Singh
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‎.DS_Store

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‎.gitignore

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.idea
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*.class
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*.iml

‎Readme.md

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‎java-arraylist-examples/.gitignore

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.idea
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*.class
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*.iml

‎java-arraylist-examples/Readme.md

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‎java-arraylist-examples/src/AccessElementsFromArrayListExample.java

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import java.util.ArrayList;
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import java.util.List;
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public class AccessElementsFromArrayListExample {
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public static void main(String[] args) {
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List<String> topCompanies = new ArrayList<>();
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// Check if an ArrayList is empty
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System.out.println("Is the topCompanies list empty? : " + topCompanies.isEmpty());
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topCompanies.add("Google");
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topCompanies.add("Apple");
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topCompanies.add("Microsoft");
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topCompanies.add("Amazon");
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topCompanies.add("Facebook");
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// Find the size of an ArrayList
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System.out.println("Here are the top " + topCompanies.size() + " companies in the world");
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System.out.println(topCompanies);
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// Retrieve the element at a given index
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String bestCompany = topCompanies.get(0);
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String secondBestCompany = topCompanies.get(1);
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String lastCompany = topCompanies.get(topCompanies.size() - 1);
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System.out.println("Best Company: " + bestCompany);
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System.out.println("Second Best Company: " + secondBestCompany);
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System.out.println("Last Company in the list: " + lastCompany);
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// Modify the element at a given index
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topCompanies.set(4, "Walmart");
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System.out.println("Modified top companies list: " + topCompanies);
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}
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}

‎java-arraylist-examples/src/ArrayListCollectionsSortExample.java

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import java.util.ArrayList;
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import java.util.Collections;
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import java.util.List;
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public class ArrayListCollectionsSortExample {
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public static void main(String[] args) {
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List<Integer> numbers = new ArrayList<>();
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numbers.add(13);
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numbers.add(7);
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numbers.add(18);
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numbers.add(5);
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numbers.add(2);
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System.out.println("Before : " + numbers);
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// Sorting an ArrayList using Collections.sort() method
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Collections.sort(numbers);
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System.out.println("After : " + numbers);
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}
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}

‎java-arraylist-examples/src/ArrayListIteratorRemoveExample.java

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import java.util.ArrayList;
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import java.util.Iterator;
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import java.util.List;
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public class ArrayListIteratorRemoveExample {
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public static void main(String[] args) {
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List<Integer> numbers = new ArrayList<>();
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numbers.add(13);
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numbers.add(18);
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numbers.add(25);
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numbers.add(40);
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Iterator<Integer> numbersIterator = numbers.iterator();
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while (numbersIterator.hasNext()) {
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Integer num = numbersIterator.next();
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if(num % 2 != 0) {
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numbersIterator.remove();
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}
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}
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System.out.println(numbers);
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}
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}

‎java-arraylist-examples/src/ArrayListObjectSortExample.java

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import java.util.ArrayList;
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import java.util.Collections;
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import java.util.Comparator;
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import java.util.List;
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class Person {
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private String name;
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private Integer age;
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public Person(String name, Integer age) {
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this.name = name;
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this.age = age;
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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 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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@Override
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public String toString() {
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return "{" +
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"name='" + name + '\'' +
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", age=" + age +
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'}';
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}
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}
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public class ArrayListObjectSortExample {
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public static void main(String[] args) {
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List<Person> people = new ArrayList<>();
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people.add(new Person("Sachin", 47));
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people.add(new Person("Chris", 34));
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people.add(new Person("Rajeev", 25));
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people.add(new Person("David", 31));
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System.out.println("Person List : " + people);
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// Sort People by their Age
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people.sort((person1, person2) -> {
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return person1.getAge() - person2.getAge();
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});
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// A more concise way of writing the above sorting function
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people.sort(Comparator.comparingInt(Person::getAge));
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System.out.println("Sorted Person List by Age : " + people);
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// You can also sort using Collections.sort() method by passing the custom Comparator
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Collections.sort(people, Comparator.comparing(Person::getName));
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System.out.println("Sorted Person List by Name : " + people);
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}
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}

‎java-arraylist-examples/src/ArrayListSortExample.java

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import java.util.ArrayList;
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import java.util.Comparator;
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import java.util.List;
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public class ArrayListSortExample {
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public static void main(String[] args) {
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List<String> names = new ArrayList<>();
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names.add("Lisa");
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names.add("Jennifer");
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names.add("Mark");
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names.add("David");
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System.out.println("Names : " + names);
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// Sort an ArrayList using its sort() method. You must pass a Comparator to the ArrayList.sort() method.
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names.sort(new Comparator<String>() {
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@Override
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public int compare(String name1, String name2) {
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return name1.compareTo(name2);
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}
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});
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// The above `sort()` method call can also be written simply using lambda expressions
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names.sort((name1, name2) -> name1.compareTo(name2));
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// Following is an even more concise solution
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names.sort(Comparator.naturalOrder());
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System.out.println("Sorted Names : " + names);
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}
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}

‎java-arraylist-examples/src/ArrayListUserDefinedObjectExample.java

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import java.util.ArrayList;
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import java.util.List;
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class User {
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private String name;
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private int age;
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public User(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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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 int getAge() {
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return age;
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}
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public void setAge(int age) {
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this.age = age;
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}
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}
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public class ArrayListUserDefinedObjectExample {
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public static void main(String[] args) {
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List<User> users = new ArrayList<>();
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users.add(new User("Rajeev", 25));
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users.add(new User("John", 34));
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users.add(new User("Steve", 29));
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users.forEach(user -> {
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System.out.println("Name : " + user.getName() + ", Age : " + user.getAge());
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});
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}
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}

‎java-arraylist-examples/src/CreateArrayListExample.java

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import java.util.ArrayList;
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import java.util.List;
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public class CreateArrayListExample {
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public static void main(String[] args) {
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// Creating an ArrayList of String using
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List<String> animals = new ArrayList<>();
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// Adding new elements to the ArrayList
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animals.add("Lion");
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animals.add("Tiger");
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animals.add("Cat");
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animals.add("Dog");
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System.out.println(animals);
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// Adding an element at a particular index in an ArrayList
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animals.add(2, "Elephant");
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System.out.println(animals);
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}
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}

‎java-arraylist-examples/src/CreateArrayListFromCollectionExample.java

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import java.util.ArrayList;
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import java.util.List;
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public class CreateArrayListFromCollectionExample {
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public static void main(String[] args) {
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List<Integer> firstFivePrimeNumbers = new ArrayList<>();
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firstFivePrimeNumbers.add(2);
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firstFivePrimeNumbers.add(3);
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firstFivePrimeNumbers.add(5);
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firstFivePrimeNumbers.add(7);
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firstFivePrimeNumbers.add(11);
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// Creating an ArrayList from another collection
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List<Integer> firstTenPrimeNumbers = new ArrayList<>(firstFivePrimeNumbers);
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List<Integer> nextFivePrimeNumbers = new ArrayList<>();
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nextFivePrimeNumbers.add(13);
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nextFivePrimeNumbers.add(17);
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nextFivePrimeNumbers.add(19);
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nextFivePrimeNumbers.add(23);
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nextFivePrimeNumbers.add(29);
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// Adding an entire collection to an ArrayList
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firstTenPrimeNumbers.addAll(nextFivePrimeNumbers);
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System.out.println(firstTenPrimeNumbers);
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}
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}

‎java-arraylist-examples/src/IterateOverArrayListExample.java

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import java.util.ArrayList;
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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 IterateOverArrayListExample {
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public static void main(String[] args) {
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List<String> tvShows = new ArrayList<>();
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tvShows.add("Breaking Bad");
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tvShows.add("Game Of Thrones");
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tvShows.add("Friends");
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tvShows.add("Prison break");
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System.out.println("=== Iterate using Java 8 forEach loop ===");
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tvShows.forEach(tvShow -> {
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System.out.println(tvShow);
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});
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System.out.println("\n=== Iterate using an iterator() ===");
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Iterator<String> tvShowIterator = tvShows.iterator();
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while (tvShowIterator.hasNext()) {
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String tvShow = tvShowIterator.next();
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System.out.println(tvShow);
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}
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System.out.println("\n=== Iterate using an iterator() and Java 8 forEachRemaining() method ===");
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tvShowIterator = tvShows.iterator();
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tvShowIterator.forEachRemaining(tvShow -> {
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System.out.println(tvShow);
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});
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System.out.println("\n=== Iterate using a listIterator() to traverse in both directions ===");
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// Here, we start from the end of the list and traverse backwards.
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ListIterator<String> tvShowListIterator = tvShows.listIterator(tvShows.size());
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while (tvShowListIterator.hasPrevious()) {
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String tvShow = tvShowListIterator.previous();
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System.out.println(tvShow);
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}
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System.out.println("\n=== Iterate using simple for-each loop ===");
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for(String tvShow: tvShows) {
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System.out.println(tvShow);
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}
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System.out.println("\n=== Iterate using for loop with index ===");
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for(int i = 0; i < tvShows.size(); i++) {
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System.out.println(tvShows.get(i));
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}
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}
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}

‎java-arraylist-examples/src/RemoveElementsFromArrayListExample.java

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import java.util.ArrayList;
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import java.util.List;
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import java.util.function.Predicate;
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public class RemoveElementsFromArrayListExample {
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public static void main(String[] args) {
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List<String> programmingLanguages = new ArrayList<>();
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programmingLanguages.add("C");
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programmingLanguages.add("C++");
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programmingLanguages.add("Java");
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programmingLanguages.add("Kotlin");
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programmingLanguages.add("Python");
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programmingLanguages.add("Perl");
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programmingLanguages.add("Ruby");
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System.out.println("Initial List: " + programmingLanguages);
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// Remove the element at index `5`
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programmingLanguages.remove(5);
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System.out.println("After remove(5): " + programmingLanguages);
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// Remove the element "Kotlin" (The remove() method returns false if the element does not exist in the ArrayList)
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boolean isRemoved = programmingLanguages.remove("Kotlin");
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System.out.println("After remove(\"Kotlin\"): " + programmingLanguages);
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// Remove all the elements belonging to the collection scriptingLanguages
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List<String> scriptingLanguages = new ArrayList<>();
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scriptingLanguages.add("Python");
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scriptingLanguages.add("Ruby");
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scriptingLanguages.add("Perl");
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programmingLanguages.removeAll(scriptingLanguages);
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System.out.println("After removeAll(scriptingLanguages): " + programmingLanguages);
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// Remove if the element matches a given predicate
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programmingLanguages.removeIf(new Predicate<String>() {
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@Override
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public boolean test(String s) {
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return s.startsWith("C");
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}
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});
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/*
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The above removeIf() call can also be written using lambda expression like this -
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programmingLanguages.removeIf(s -> s.startsWith("C"))
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*/
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System.out.println("After Removing all elements that start with \"C\": " + programmingLanguages);
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// Remove all elements from the ArrayList
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programmingLanguages.clear();
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System.out.println("After clear(): " + programmingLanguages);
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}
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}

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