Java ArrayList add() method with Examples

by Online Tutorials Library July 22, 2022

Java ArrayList add method

Java ArrayList add(E element) method

The ArrayListadd(E element) methodof Java ArrayList classappends a new value to the end of this list.

Syntax:

Parameter:

Here, “element” is an element to be appended to the list.

Return:

It always return “true”. Don’t worry about the Boolean return value. It always there as other classes in the collections family need a return value in the signature when adding an element.

Example 1

  import java.util.ArrayList;  public class ArrayListAddExample1{  public static void main(String[] args) {  ArrayList list = new ArrayList();  list.add(“element1”);// [element1]  list.add(Boolean.TRUE);// [element1, true]  list.add(“last element”)// [element1, true, last element]  System.out.println(list);// [element1, true, last element]  }  }  

Test it Now

Output:

[element1, true, last element]

Example 2

  import java.util.ArrayList;  public class ArrayListAddExample2{  public static void main(String[] args){  ArrayList<Integer> id = new ArrayList<>();  list.add(1); // [1]  list.add(“student id”);// does not compile   }  }  

Test it Now

Output:

does not compile.

This time the compiler knows that only Integer values are allowed in and prevents the attempt to add a String value.

Java ArrayList add(int index, E element) method

The add(int index, E element) method of Java ArrayList class inserts a specific element in a specific index of ArrayList. It shifts the element of indicated index if exist and subsequent elements to the right.

Syntax:

Parameter:

“index”: index at which the element will be inserted.

“element”: is an element to be inserted.

Return:

Return nothing.

Example 3

  import java.util.ArrayList;  public class ArrayListAddExample3{  public static void main(String[] args){  List<String> colors = new ArrayList<>();  colors.add(“red”);// [“red”]  colors.add(“blue”);// [“red” , “blue”]  colors.add(1, “white”);// [“red” , “white”, “blue”]  colors.add(0, “black”);// [“black”, “red” , “white”, “blue”]  System.out.println(colors);// [“black”, “red” , “white”, “blue”]  }  }  

Test it Now

Output:

["black", "red" , "white", "blue"]

Example 4

  import java.util.ArrayList;  public class ArrayListAddExample4{  public static void main(String[] args){  List<Object> list = new ArrayList<>();  list.add(0, “e1”);// [“e1”]  list.add(1);// [“e1” , 1]  list.add(1, “e2”);// [“e1”, “e2”, 1]  list.add(0, 1);// [1, “e1”, “e2” , 1]  System.out.println(list);// [1, “e1”, “e2” , 1]  }  }  

Test it Now

Output:

[1, "e1", "e2" , 1]

Example 5

  import java.util.ArrayList;  public class ArrayListAddExample5{  public static void main(String[] args){  List<Object> list = new ArrayList<>();  list.add(0, “element1”);// [“element1”]  list.add(1, “element2”);// [“element1”, “element2”]  list.add(3, “element2”);// throws IndexOutOfBoundsException  }  }  

Test it Now

Output:

throwsIndexOutOfBoundsException

Next TopicJava ArrayList

add()addAll()arraylist clear()clone()contains()ensureCapacity()get indexOf()isempty()iterator java lastIndexOf()ListIterator remove removeall subList()toArray()trimToSize()

Java ArrayList add() method with Examples

Java ArrayList add method

Java ArrayList add(E element) method

Syntax:

Parameter:

Return:

Example 1

Example 2

Java ArrayList add(int index, E element) method

Syntax:

Parameter:

Return:

Example 3

Example 4

Example 5

Java ThreadLocalRandom setSeed() Method with Examples

Java Boolean toString() Method with Examples

You may also like