How to make Read Only Map in Java Example

Read Only Map in Java

In this example, We will show you how to make read only map in java.

Example Program

package com.dineshkrish;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
/**
* 
* @author Dinesh Krishnan
*
*/
public class ReadOnlyMap {
public static void main(String[] args) {
// defining map object
Map<Integer, String> map = new HashMap<Integer, String>();
// adding the elements to map
map.put(1, "One");
map.put(2, "Two");
map.put(3, "Three");
map.put(4, "Four");
map.put(5, "Five");
// making read only map
map = Collections.unmodifiableMap(map);
// trying to update the map obejct
map.put(6, "One");
}
}

Run it

[su_highlight]Exception in thread “main” java.lang.UnsupportedOperationException
at java.util.Collections$UnmodifiableMap.put(Unknown Source)
at com.dineshkrish.ReadOnlyMap.main(ReadOnlyMap.java:31)
[/su_highlight]

References

1. Java List Interface
2. Java ArrayList Class
3. Java Collections Class
4. Java Collections.unmodifiableMap() Method

Dinesh Krishnan

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