Java ConcurrentHashMap clear() Method

The clear() method of Constructor class removes all of the mappings from this map.

Syntax

Parameter

No any parameter is passed.

Returns

Throws

No exception is thrown.

Example 1

import java.util.concurrent.ConcurrentHashMap; 
import java.util.*; 
  
public class ConcurrentHashMapclearExample1 { 
  
    public static void main(String[] args) 
    { 
        Map<String, String> chm = new ConcurrentHashMap<String, String>(); 
  //put is used to add value to map
        chm.put("1", "1"); 
        chm.put("2", "10"); 
        chm.put("3", "100"); 
        chm.put("4", "2"); 
        chm.put("5", "20"); 
        chm.put("6", "200"); 
  
        System.out.println("Values in map: \n"
                           + chm); 
        chm.clear(); // clear will clear all the values in map.
        System.out.println("Map after calling clear(): "
                           + chm); 
    } 
} 

Test it Now

Output:

Values in map: 
{1=1, 2=10, 3=100, 4=2, 5=20, 6=200}
Map after calling clear(): {}

Example 2

import java.util.concurrent.ConcurrentHashMap; 
import java.util.*; 
  
public class ConcurrentHashMapclearExample2 { 
  
    public static void main(String[] args) 
    { 
        Map<String, String> chm2 = new ConcurrentHashMap<String, String>(); 
  //put is used to add value to map
  //map can also have string as key 
        chm2.put("a", "1"); 
        chm2.put("b", "10"); 
        chm2.put("c", "100"); 
        chm2.put("d", "2"); 
        chm2.put("e", "20"); 
        chm2.put("f", "200"); 
  
        System.out.println("Values in map: \n"
                           + chm2); 
        chm2.clear(); // clear will clear all the values in map.
        System.out.println("Map after calling clear(): "
                           + chm2); 
    } 
} 

Test it Now

Output:

Values in map: 
{a=1, b=10, c=100, d=2, e=20, f=200}
Map after calling clear(): {}

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