Java Collections emptyList() Method

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Description

The Java Collections emptyList() method is used to get the empty list. List is immutable and cannot be modified. This list is serializable.

Declaration

Following is the declaration for Java Collections emptyList() method.

public static final <T> List<T> emptyList()

Parameters

NA

Return Value

NA

Exception

NA

Getting Empty List of Integers Example

The following example shows the usage of Java Collection emptyList() method to get an empty list of Integers. We've created an empty list using emptyList() method and then tried adding few elements to it which results in exception.

 
package com.tutorialspoint;

import java.util.Collections;
import java.util.List;

public class CollectionsDemo {
   public static void main(String args[]) {
      
      // create an empty list    
      List<Integer> emptylst = Collections.emptyList();

      System.out.println("Created empty immutable list: "+emptylst);

      // try to add elements
      emptylst.add(1);
      emptylst.add(2);
   }    
}

Output

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

Created empty immutable list: []
Exception in thread "main" java.lang.UnsupportedOperationException
	at java.base/java.util.AbstractList.add(AbstractList.java:153)
	at java.base/java.util.AbstractList.add(AbstractList.java:111)
	at com.tutorialspoint.CollectionsDemo.main(CollectionsDemo.java:15)

Getting Empty List of Strings Example

The following example shows the usage of Java Collection emptyList() method to get an empty list of Strings. We've created an empty list using emptyList() method and then tried adding few elements to it which results in exception.

 
package com.tutorialspoint;

import java.util.Collections;
import java.util.List;

public class CollectionsDemo {
   public static void main(String args[]) {
      
      // create an empty list    
      List<String> emptylst = Collections.emptyList();

      System.out.println("Created empty immutable list: "+emptylst);

      // try to add elements
      emptylst.add("A");
      emptylst.add("B");
   }    
}

Output

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

Created empty immutable list: []
Exception in thread "main" java.lang.UnsupportedOperationException
	at java.base/java.util.AbstractList.add(AbstractList.java:153)
	at java.base/java.util.AbstractList.add(AbstractList.java:111)
	at com.tutorialspoint.CollectionsDemo.main(CollectionsDemo.java:15)

Getting Empty List of Objects Example

The following example shows the usage of Java Collection emptyList() method to get an empty list of Student objects. We've created an empty list using emptyList() method and then tried adding few elements to it which results in exception.

 
package com.tutorialspoint;

import java.util.Collections;
import java.util.List;

public class CollectionsDemo {
   public static void main(String args[]) {
      
      // create an empty list    
      List<Student> emptylst = Collections.emptyList();

      System.out.println("Created empty immutable list: "+emptylst);

      // try to add elements
      emptylst.add(new Student(1, "Julie"));
      emptylst.add(new Student(2, "Robert"));
   }    
}
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 list is immutable.

Created empty immutable list: []
Exception in thread "main" java.lang.UnsupportedOperationException
	at java.base/java.util.AbstractList.add(AbstractList.java:153)
	at java.base/java.util.AbstractList.add(AbstractList.java:111)
	at com.tutorialspoint.CollectionsDemo.main(CollectionsDemo.java:15)