Java Collections unmodifiableNavigableMap() Method with Examples

Last Updated : 03 Jan, 2022

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)