Java Collections emptySortedMap() Method

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Description

The Java Collections emptySortedMap() method is used to get the empty sorted map (immutable). This sorted map is serializable.

Declaration

Following is the declaration for java.util.Collections.emptySortedMap() method.

public static final <K,V> SortedMap<K,V> emptySortedMap()

Parameters

NA

Return Value

NA

Exception

NA

Getting Empty SortedMap of String, Integer Pair Example

The following example shows the usage of Java Collection emptySortedMap() method to get an empty sorted map of String, Integer pairs. We've created an empty sorted map using emptySortedMap() method and then tried adding few elements to it which results in exception.

 
package com.tutorialspoint;

import java.util.Collections;
import java.util.SortedMap;

public class CollectionsDemo {
   public static void main(String args[]) {
      
      // create an empty sorted map    
      SortedMap<String, Integer> emptySortedMap = Collections.emptySortedMap();

      System.out.println("Created empty immutable sorted map: "+emptySortedMap);

      // try to add elements
      emptySortedMap.put("1", 1);
      emptySortedMap.put("2", 2);
   }    
}

Output

Let us compile and run the above program, this will produce the following result. Exception will be thrown as the sorted map is immutable.

Created empty immutable sorted map: {}
Exception in thread "main" java.lang.UnsupportedOperationException
	at java.base/java.util.AbstractMap.put(AbstractMap.java:209)
	at com.tutorialspoint.CollectionsDemo.main(CollectionsDemo.java:15)

Getting Empty SortedMap of String, String Pair Example

The following example shows the usage of Java Collection emptySortedMap() method to get an empty sorted map of String, String pairs. We've created an empty sorted map using emptySortedMap() method and then tried adding few elements to it which results in exception.

 
package com.tutorialspoint;

import java.util.Collections;
import java.util.SortedMap;

public class CollectionsDemo {
   public static void main(String args[]) {
      
      // create an empty sorted map    
      SortedMap<String, String> emptySortedMap = Collections.emptySortedMap();

      System.out.println("Created empty immutable sorted map: "+emptySortedMap);

      // try to add elements
      emptySortedMap.put("1", "A");
      emptySortedMap.put("2", "B");
   }    
}

Output

Let us compile and run the above program, this will produce the following result. Exception will be thrown as the sorted map is immutable.

Created empty immutable sorted map: {}
Exception in thread "main" java.lang.UnsupportedOperationException
	at java.base/java.util.AbstractMap.put(AbstractMap.java:209)
	at com.tutorialspoint.CollectionsDemo.main(CollectionsDemo.java:15)

Getting Empty SortedMap of String, Object Pair Example

The following example shows the usage of Java Collection emptySortedMap() method to get an empty sorted map of String, Student object pairs. We've created an empty sorted map using emptySortedMap() method and then tried adding few elements to it which results in exception.

 
package com.tutorialspoint;

import java.util.Collections;
import java.util.SortedMap;

public class CollectionsDemo {
   public static void main(String args[]) {
      
      // create an empty sorted map    
      SortedMap<String, Object> emptySortedMap = Collections.emptySortedMap();

      System.out.println("Created empty immutable sorted map: "+emptySortedMap);

      // try to add elements
      emptySortedMap.put("1", new Student(1, "Julie"));
      emptySortedMap.put("2", new Student(2, "Jene"));
   }    
}
class Student {
   int rollNo;
   String name;

   Student(int rollNo, String name){
      this.rollNo = rollNo;
      this.name = name;
   }

   @Override
   public String toString() {
      return "[ " + this.rollNo + ", " + this.name + " ]";
   }
}

Output

Let us compile and run the above program, this will produce the following result. Exception will be thrown as the sorted map is immutable.

Created empty immutable sorted map: {}
Exception in thread "main" java.lang.UnsupportedOperationException
	at java.base/java.util.AbstractMap.put(AbstractMap.java:209)
	at com.tutorialspoint.CollectionsDemo.main(CollectionsDemo.java:15)