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 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);
}
} |
TreeSet: [4, Geeks, To, TreeSet, Welcome] TreeSet: [4, Geeks, Hello, To, TreeSet, Welcome, World]
Program 2 : Appending an ArrayList.
// 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);
}
} |
TreeSet: [4, Geeks, To, TreeSet, Welcome] Final TreeSet: [4, A, Computer, Geeks, Portal, To, TreeSet, Welcome]