Remove all values from TreeMap in Java

Use the clear() method to remove all values from TreeMap.

Let us first create a TreeMap −

TreeMap<Integer,String> m = new TreeMap<Integer,String>();

Add some elements to the TreeMap −

m.put(1,"PHP");
m.put(2,"jQuery");
m.put(3,"JavaScript");
m.put(4,"Ruby");
m.put(5,"Java");
m.put(6,"AngularJS");
m.put(7,"ExpressJS");

Let us now remove all the values −

m.clear();

The following is an example to remove all values from TreeMap −

Example

 Live Demo

import java.util.*;
public class Demo {
   public static void main(String args[]) {
      TreeMap<Integer,String> m = new TreeMap<Integer,String>();
      m.put(1,"PHP");
      m.put(2,"jQuery");
      m.put(3,"JavaScript");
      m.put(4,"Ruby");
      m.put(5,"Java");
      m.put(6,"AngularJS");
      m.put(7,"ExpressJS");
      System.out.println("TreeMap Elements...");
      Collection res = m.values();
      Iterator i = res.iterator();
      while (i.hasNext()){
         System.out.println(i.next());
      }
      System.out.println("TreeMap size = "+m.size());
      m.clear();
      System.out.println("\nTreeMap after removing all elements = "+m);
      System.out.println("Size of TreeMap now = "+m.size());
   }
}

Output

TreeMap Elements...
PHP
jQuery
JavaScript
Ruby
Java
AngularJS
ExpressJS
TreeMap size = 7
TreeMap after removing all elements = {}
Size of TreeMap now = 0