Java LinkedList isEmpty() Method

Description

The Java LinkedList isEmpty() method returns true if this list contains no elements. This method always returns the result as per the current state of the list. If an element is added then isEmpty() will return false.

Declaration

Following is the declaration for java.util.LinkedList.isEmpty() method

public boolean isEmpty()

Parameters

NA

Return Value

This method returns true if this list contains no elements, else false.

Exception

NA

Checking Emptyness of LinkedList of Integers Example

The following example shows the usage of Java LinkedList isEmpty() method. Here we are working with an LinkedList of Integers. At first, we initialize an LinkedList object and then check if it is empty or not. Then we'll be adding few elements and then check again if LinkedList object is empty or not.

package com.tutorialspoint;

import java.util.LinkedList;

public class LinkedListDemo {
   public static void main(String[] args) {
      
      // create an empty linked list 
      LinkedList<Integer> linkedList = new LinkedList<>();

      if (linkedList.isEmpty()) {
         System.out.println("linkedList is empty");
      } else {
         System.out.println("linkedList is not empty");
      }

      // printing all the elements available in linkedList
      System.out.println("LinkedList = " + linkedList);
	  
      // use add() method to add elements in the linkedList
      linkedList.add(0);
      linkedList.add(1);
      linkedList.add(2);
      linkedList.add(3);
      linkedList.add(4);
      linkedList.add(5);
      linkedList.add(6);
	
      if (linkedList.isEmpty()) {
         System.out.println("linkedList is empty");
      } else {
         System.out.println("linkedList is not empty");
      }

      // printing all the elements available in linkedList
      System.out.println("LinkedList = " + linkedList);
   }
}

Let us compile and run the above program, this will produce the following result −

linkedList is empty
LinkedList = []
linkedList is not empty
LinkedList = [0, 1, 2, 3, 4, 5, 6]

Checking Emptyness of LinkedList of String Example

The following example shows the usage of Java LinkedList isEmpty() method. Here we are working with an LinkedList of Strings. At first, we initialize an LinkedList object and then check if it is empty or not. Then we'll be adding few elements and then check again if LinkedList object is empty or not.

package com.tutorialspoint;

import java.util.LinkedList;

public class LinkedListDemo {
   public static void main(String[] args) {
      
      // create an empty linked list
      LinkedList<String> linkedList = new LinkedList<>();

      if (linkedList.isEmpty()) {
         System.out.println("linkedList is empty");
      } else {
         System.out.println("linkedList is not empty");
      }

      // printing all the elements available in linkedList
      System.out.println("LinkedList = " + linkedList);

      // use add() method to add elements in the linkedList
      linkedList.add("A");
      linkedList.add("B");
      linkedList.add("C");
	  
      if (linkedList.isEmpty()) {
         System.out.println("linkedList is empty");
      } else {
         System.out.println("linkedList is not empty");
      }

      // printing all the elements available in linkedList
      System.out.println("LinkedList = " + linkedList);     
   }
}

Let us compile and run the above program, this will produce the following result −

linkedList is empty
LinkedList = []
linkedList is not empty
LinkedList = [A, B, C]

Checking Emptyness of LinkedList of Objects Example

The following example shows the usage of Java LinkedList isEmpty() method. Here we are working with an LinkedList of Student objects. At first, we initialize an LinkedList object and then check if it is empty or not. Then we'll be adding few elements and then check again if LinkedList object is empty or not.

package com.tutorialspoint;

import java.util.LinkedList;

public class LinkedListDemo {
   public static void main(String[] args) {

      // create an empty linkedList
      LinkedList<Student> linkedList = new LinkedList<>();
      
      if (linkedList.isEmpty()) {
         System.out.println("linkedList is empty");
      } else {
         System.out.println("linkedList is not empty");
      }

      // printing all the elements available in linkedList
      System.out.println("LinkedList = " + linkedList);
      // use add() method to add elements in the linkedList
      linkedList.add(new Student(1, "Julie"));
      linkedList.add(new Student(2, "Robert"));
      linkedList.add(new Student(3, "Adam"));

      if (linkedList.isEmpty()) {
         System.out.println("linkedList is empty");
      } else {
         System.out.println("linkedList is not empty");
      }

      // printing all the elements available in linkedList
      System.out.println("LinkedList = " + linkedList);     
   }
}

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 + " ]";
   }
   
   @Override
   public boolean equals(Object obj) {
      Student s = (Student)obj;
      return this.rollNo == s.rollNo && this.name.equalsIgnoreCase(s.name);
   }
}

Let us compile and run the above program, this will produce the following result −

linkedList is empty
LinkedList = []
linkedList is not empty
LinkedList = [[ 1, Julie ], [ 2, Robert ], [ 3, Adam ]]