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Ilias is a software developer turned online entrepreneur. He is co-founder and Executive Editor at Java Code Geeks.

Remove all elements from TreeSet example

With this example we are going to demonstrate how to remove all elements from a TreeSet. The TreeSet API provides methods for clearing a set and checking if it is empty. In short, to remove all elements from a TreeSet you should:

  • Create a new TreeSet.
  • Populate the set with elements, with add(E e) API method of TreeSet.
  • Invoke clear(), or removeAll(Collection c) API methods to remove all elements from the TreeSet.
  • Invoke the isEmpty() API method of TreeSet to check if the set has any elements. It returns true if the set is empty.

Let’s take a look at the code snippet that follows:

package com.javacodegeeks.snippets.core;

import java.util.TreeSet;
public class RemoveAllElementsTreeSet {
  public static void main(String[] args) {
    // Create a TreeSet and populate it with elements
    TreeSet treeSet = new TreeSet();
    // boolean isEmpty() method checks whether TreeSet contains any elements or not   
    System.out.println("TreeSet empty : " + treeSet.isEmpty());
    // Remove all element from the TreeSet using clear() or removeAll() methods
    System.out.println("TreeSet empty : " + treeSet.isEmpty());



TreeSet empty : false
TreeSet empty : true

This was an example of how to remove all elements from a TreeSet in Java.

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