Java Collections.checkedMap() method

The java.util.Collections class consists exclusively of static methods that operate on or return collections. It contains polymorphic algorithms that operate on collections, “wrappers”, which return a new collection backed by a specified collection, and a few other odds and ends.

Collections.checkedMap() method will returns a dynamically typesafe view of the specified map.
Syntax: public static Map checkedMap(Map m,Class keyType,Class valueType)


package com.w3spoint;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;
public class Test { 
    public static void main(String a[]){         
    	Map map = new HashMap();
        Map chekedMap = Collections.checkedMap(map, String.class, Integer.class);
        System.out.println("Checked Map content: "+chekedMap);
        chekedMap.put(6,"anil"); //throws ClassCastException


Checked Map content: {mahesh=2, rahul=3, vikas=1, amit=4}
Exception in thread "main" java.lang.ClassCastException: Attempt to insert class java.lang.Integer key into collection with key type class java.lang.String
	at java.util.Collections$CheckedMap.typeCheck(
	at java.util.Collections$CheckedMap.put(
	at com.w3spoint.Test.main(

Java Collections class examples

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