Java Collections unmodifiableNavigableMap​() Method with Examples

The unmodifiableMap() in java collections is used to get the unmodifiable view for the given map.

Syntax:

public static <Key,Value> Map<Key,Value> unmodifiableMap(Map<? extends Key, ? extends Key> map)

Parameters:

• Key is the key-value type
• Value is the value type
• map is the input map

Return: It will return the unmodifiable view for the given map.

Exceptions: This method will not throw any kind of exception.

Example 1:

Java

// Java program to create a map with
// string values and get the
// unmodifiable view
import java.util.*;

public class GFG {
    // main method
    public static void main(String[] args)
    {
        // create hashmap
        HashMap<String, String> data
            = new HashMap<String, String>();

        // add elements to the created hashmap
        data.put("1", "manoj");
        data.put("2", "sai");
        data.put("3", "ramya");
        data.put("4", "sravan");

        // display the data
        System.out.println(data);

        // Create unmodifiable map  for the above map
        Map<String, String> final1
            = Collections.unmodifiableMap(data);

        // display unmodifiable map
        System.out.println(final1);
    }
}

Output

{1=manoj, 2=sai, 3=ramya, 4=sravan}
{1=manoj, 2=sai, 3=ramya, 4=sravan}

Example 2: 

Java

// Java program to create a map
// with integer values and get
// the unmodifiable view
import java.util.*;

public class GFG {
    // main method
    public static void main(String[] args)
    {
        // create hashmap
        HashMap<Integer, Integer> data
            = new HashMap<Integer, Integer>();

        // add elements to the created hashmap
        data.put(1, 67);
        data.put(2, 34);

        // display the data
        System.out.println(data);

        // Create unmodifiable map  for the above map
        Map<Integer, Integer> final1
            = Collections.unmodifiableMap(data);

        // display unmodifiable map
        System.out.println(final1);
    }
}

Output

{1=67, 2=34}
{1=67, 2=34}

Example 3: It will throw an error when we add an element to a modifiable map.

Java

import java.util.*;

public class GFG {
    // main method
    public static void main(String[] args)
    {

        // create hashmap
        HashMap<Integer, Integer> data
            = new HashMap<Integer, Integer>();

        // add elements to the created hashmap
        data.put(1, 67);
        data.put(2, 34);

        // display the data
        System.out.println(data);

        // Create unmodifiable map  for the above map
        Map<Integer, Integer> final1
            = Collections.unmodifiableMap(data);

        // put value in unmodifiable map
        final1.put(3, 45);

        // display unmodifiable map
        System.out.println(final1);
    }
}

Output:

{1=67, 2=34}
Exception in thread "main" java.lang.UnsupportedOperationException
    at java.util.Collections$UnmodifiableMap.put(Collections.java:1459)
    at GFG.main(GFG.java:21)