The java.util.TreeSet.addAll(Collection C) method is used to append all of the elements from the mentioned collection to the existing set. The elements are added randomly without following any specific order.
Syntax:
boolean addAll(Collection C)
Parameters: The parameter C is a collection of any type that is to be added to the tree set.
Return Value: The method returns true if it successfully appends the elements of the collection C to the TreeSet otherwise it returns False.
Below programs illustrate the Java.util.TreeSet.addAll() method:
Program 1 : Appending a tree set.
Java
// Java code to illustrate addAll()import java.io.*;import java.util.TreeSet;public class TreeSetDemo { public static void main(String args[]) { // Creating an empty TreeSet TreeSet<String> tree = new TreeSet<String>(); // Use add() method to add elements into the Set tree.add("Welcome"); tree.add("To"); tree.add("Geeks"); tree.add("4"); tree.add("Geeks"); tree.add("TreeSet"); // Displaying the TreeSet System.out.println("TreeSet: " + tree); // Creating anothe TreeSet TreeSet<String> tree_two = new TreeSet<String>(); // Use add() method to add elements into the Set tree_two.add("Hello"); tree_two.add("World"); // Using addAll() method to Append tree.addAll(tree_two); // Displaying the final tree System.out.println("TreeSet: " + tree); }} |
Output:
TreeSet: [4, Geeks, To, TreeSet, Welcome] TreeSet: [4, Geeks, Hello, To, TreeSet, Welcome, World]
Program 2 : Appending an ArrayList.
Java
// Java code to illustrate addAll()import java.io.*;import java.util.TreeSet;import java.util.ArrayList;public class TreeSetDemo { public static void main(String args[]) { // Creating an empty TreeSet TreeSet<String> tree = new TreeSet<String>(); // Use add() method to add elements into the Set tree.add("Welcome"); tree.add("To"); tree.add("Geeks"); tree.add("4"); tree.add("Geeks"); tree.add("TreeSet"); // Displaying the TreeSet System.out.println("TreeSet: " + tree); // An array collection is created ArrayList<String> collect = new ArrayList<String>(); collect.add("A"); collect.add("Computer"); collect.add("Portal"); // Using addAll() method to Append tree.addAll(collect); // Displaying the final tree System.out.println("Final TreeSet: " + tree); }} |
Output:
TreeSet: [4, Geeks, To, TreeSet, Welcome] Final TreeSet: [4, A, Computer, Geeks, Portal, To, TreeSet, Welcome]
