LinkedList addAll() Method in Java

  1. java.util.LinkedList.addAll(Collection C): This method is used to append all of the elements from the collection passed as parameter to this function to the end of a list keeping in mind the order of return by the collections iterator.

    Syntax:

    boolean addAll(Collection C)

    Parameters: The parameter C is a collection of ArrayList. It is the collection whose elements are needed to be appended at the end of the list.



    Return Value: The method returns true if at least one action of append is performed.

    Below program illustrate the Java.util.LinkedList.addAll() method:

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    // Java code to illustrate boolean addAll()
    import java.util.*;
    import java.util.LinkedList;
    import java.util.ArrayList;
      
    public class LinkedListDemo {
       public static void main(String args[]) {
      
          // Creating an empty LinkedList
          LinkedList<String> list = new LinkedList<String>();
      
          // Use add() method to add elements in the list
          list.add("Geeks");
          list.add("for");
          list.add("Geeks");
          list.add("10");
          list.add("20");
            
          // A collection is created
          Collection<String> collect = new ArrayList<String>();
          collect.add("A");
          collect.add("Computer");
          collect.add("Portal");
          collect.add("for");
          collect.add("Geeks");
      
          // Displaying the list
          System.out.println("The LinkedList is: " + list);
                  
          // Appending the collection to the list
          list.addAll(collect);
      
         // Clearing the list using clear() and displaying
         System.out.println("The new linked list is: " + list);
      
       }
    }

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    Output:

    The LinkedList is: [Geeks, for, Geeks, 10, 20]
    The new linked list is: [Geeks, for, Geeks, 10, 20, A, Computer, Portal, for, Geeks]
    
  2. java.util.LinkedList.addAll(int index, Collection C): This method is used to append all of the elements from the collection passed as parameter to this function at a specific index or position of a list.

    Syntax:

    boolean addAll(int index, Collection C)

    Parameters: This function accepts two parameters as shown in the above syntax and are described below.

    • index: This parameter is of integer datatype and specifies the position in the list starting from where the elements from the container will be inserted.
    • C: It is a collection of ArrayList. It is the collection whose elements are needed to be appended.

    Return Value: The method returns TRUE if at least one action of append is performed.

    Below program illustrate the Java.util.LinkedList.addAll() method:

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    // Java code to illustrate boolean addAll()
    import java.util.*;
    import java.util.LinkedList;
    import java.util.ArrayList;
      
    public class LinkedListDemo {
       public static void main(String args[]) {
      
          // Creating an empty LinkedList
          LinkedList<String> list = new LinkedList<String>();
      
          // Use add() method to add elements in the list
          list.add("Geeks");
          list.add("for");
          list.add("Geeks");
          list.add("10");
          list.add("20");
            
          // Creating a Collection
          Collection<String> collect = new ArrayList<String>();
          collect.add("A");
          collect.add("Computer");
          collect.add("Portal");
          collect.add("for");
          collect.add("Geeks");
      
          // Displaying the list
          System.out.println("The LinkedList is: " + list);
                  
          // Appending the collection to the list
          list.addAll(1, collect);
      
         // Clearing the list using clear() and displaying
         System.out.println("The new linked list is: " + list);
      
       }
    }

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    Output:

    The LinkedList is: [Geeks, for, Geeks, 10, 20]
    The new linked list is: [Geeks, A, Computer, Portal, for, Geeks, for, Geeks, 10, 20]
    


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