Java.util.ArrayList.addall() method in Java

Below are the addAll() methods of ArrayList in Java:

  1. boolean addAll(Collection c) : This method appends all of the elements in the specified collection to the end of this list, in the order that they are returned by the specified collection’s Iterator. The behavior of this operation is undefined if the specified collection is modified while the operation is in progress(implies that the behavior of this call is undefined if the specified collection is this list, and this list is nonempty).
    Parameters:
    c : This is the collection containing elements to be added to this list.
    Exception:
    NullPointerException : If the specified collection is null
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    // Java program to illustrate
    // boolean addAll(Collection c)
    import java.io.*;
    import java.util.ArrayList;
      
    public class ArrayListDemo {
        public static void main(String args[])
        {
      
            // create an empty array list1 with initial 
            // capacity as 5
            ArrayList<Integer> arrlist1 = 
                               new ArrayList<Integer>(5);
      
            // use add() method to add elements in the list
            arrlist1.add(12);
            arrlist1.add(20);
            arrlist1.add(45);
      
            // prints all the elements available in list1
            System.out.println("Printing list1:");
            for (Integer number : arrlist1) 
                System.out.println("Number = " + number);        
      
            // create an empty array list2 with an initial
            // capacity
            ArrayList<Integer> arrlist2 = 
                                 new ArrayList<Integer>(5);
      
            // use add() method to add elements in list2
            arrlist2.add(25);
            arrlist2.add(30);
            arrlist2.add(31);
            arrlist2.add(35);
      
            // let us print all the elements available in 
            // list2
            System.out.println("Printing list2:");
            for (Integer number : arrlist2) 
                System.out.println("Number = " + number);        
      
            // inserting all elements, list2 will get printed
            // after list1
            arrlist1.addAll(arrlist2);
      
            System.out.println("Printing all the elements");
            // let us print all the elements available in 
            // list1
            for (Integer number : arrlist1) 
                System.out.println("Number = " + number);        
        }
    }

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    Output:Printing list1:
    Number = 12
    Number = 20
    Number = 45
    Printing list2:
    Number = 25
    Number = 30
    Number = 31
    Number = 35
    Printing all the elements
    Number = 12
    Number = 20
    Number = 45
    Number = 25
    Number = 30
    Number = 31
    Number = 35
    

    boolean addAll(int index, Collection c):This method inserts all of the elements in the specified collection into this list, starting at the specified position. It shifts the element currently at that position (if any) and any subsequent elements to the right (increases their indices). The new elements will appear in the list in the order that they are returned by the specified collection’s iterator.

    Parameters:
    index : The index at which to insert the first element from the specified collection.
    c : This is the collection containing elements to be added to this list.
    Exception:
    IndexOutOfBoundsException : If the index is out of range
    NullPointerException : If the specified collection is null
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    // Java program to illustrate
    // boolean addAll(int index, Collection c)
    import java.io.*;
    import java.util.ArrayList;
      
    public class ArrayListDemo {
        public static void main(String args[])
        {
      
            // create an empty array list1 with initial
            // capacity 5
            ArrayList<Integer> arrlist = 
                            new ArrayList<Integer>(5);
      
            // using add() method to add elements in the 
            // list
            arrlist.add(12);
            arrlist.add(20);
            arrlist.add(45);
      
            // prints all the elements available in list1
            System.out.println("Printing list1:");
            for (Integer number : arrlist) 
                System.out.println("Number = " + number);        
      
            // create an empty array list2 with an initial
            // capacity
            ArrayList<Integer> arrlist2 = 
                                new ArrayList<Integer>(5);
      
            // use add() method to add elements in list2
            arrlist2.add(25);
            arrlist2.add(30);
            arrlist2.add(31);
            arrlist2.add(35);
      
            // prints all the elements available in list2
            System.out.println("Printing list2:");
            for (Integer number : arrlist2) 
                System.out.println("Number = " + number);        
      
            // inserting all elements of list2 at third 
            // position
            arrlist.addAll(2, arrlist2);
      
            System.out.println("Printing all the elements");
      
            // prints all the elements available in list1
            for (Integer number : arrlist) 
                System.out.println("Number = " + number);        
        }
    }

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    Output:Printing list1:
    Number = 12
    Number = 20
    Number = 45
    Printing list2:
    Number = 25
    Number = 30
    Number = 31
    Number = 35
    Printing all the elements
    Number = 12
    Number = 20
    Number = 25
    Number = 30
    Number = 31
    Number = 35
    Number = 45
    

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