Java Stack empty() Method

Description

The Java Stack empty() method is used to test if this stack is or not.

Declaration

Following is the declaration for java.util.Stack.empty() method.

public boolean empty()

Parameters

NA

Return Value

The method call returns 'true' if and only if this stack contains no items; false otherwise.

Exception

NA

Empty check of Stack of Integers Example

The following example shows the usage of Java Stack empty() method to check if a stack is empty or not. In this example, we've created a Stack object of Integers. As first step, we've printed the status of stack as empty using empty() method. Then we've added few integers to the stack and printed the status of stack as non-empty using empty() method.

package com.tutorialspoint;

import java.util.Stack;

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

      // creating stack
      Stack<Integer> st = new Stack<>();

      // checking stack
      System.out.println("Is stack empty: "+st.empty());

      // populating stack
      st.push(10);
      st.push(20);
      st.push(30);

      // checking stack
      System.out.println("Is stack empty: "+st.empty());
   }    
}

Output

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

Is stack empty: true
Is stack empty: false

Empty check of Stack of Strings Example

The following example shows the usage of Java Stack empty() method to check if a stack is empty or not. In this example, we've created a Stack object of Strings. As first step, we've printed the status of stack as empty using empty() method. Then we've added few strings to the stack and printed the status of stack as non-empty using empty() method.

package com.tutorialspoint;

import java.util.Stack;

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

      // creating stack
      Stack<String> st = new Stack<>();

      // checking stack
      System.out.println("Is stack empty: "+st.empty());

      // populating stack
      st.push("tutorials");
      st.push("points");
      st.push(".com");

      // checking stack
      System.out.println("Is stack empty: "+st.empty());
   }    
}

Output

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

Is stack empty: true
Is stack empty: false

Empty check of Stack of Objects Example

The following example shows the usage of Java Stack empty() method to check if a stack is empty or not. In this example, we've created a Stack object of Student objects. As first step, we've printed the status of stack as empty using empty() method. Then we've added few students to the stack and printed the status of stack as non-empty using empty() method.

package com.tutorialspoint;

import java.util.Stack;

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

      // creating stack
      Stack<Student> st = new Stack<>();

      // checking stack
      System.out.println("Is stack empty: "+st.empty());

      // populating stack
      st.push(new Student(1, "Julie"));
      st.push(new Student(2, "Robert"));
      st.push(new Student(3, "Adam"));
	  
      // checking stack
      System.out.println("Is stack empty: "+st.empty());
   }    
}
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.

Is stack empty: true
Is stack empty: false