Java Stack isEmpty()方法及示例

Java.util.Stack .isEmpty()方法用于检查和验证一个堆栈是否为空。如果堆栈是空的，它返回True，否则返回False。

语法

Stack.isEmpty()

参数： 该方法不接受任何参数。

返回值： 如果Stack是空的，该函数返回True，否则返回False。

以下程序说明了Java.util.Stack.isEmpty()方法。

程序1 :

// Java code to illustrate isEmpty()
import java.util.*;
  
public class StackDemo {
    public static void main(String args[])
    {
        // Creating an empty Stack
        Stack<String> stack = new Stack<String>();
  
        // Use add() method to add elements into the Stack
        stack.add("Welcome");
        stack.add("To");
        stack.add("Geeks");
        stack.add("4");
        stack.add("Geeks");
  
        // Displaying the Stack
        System.out.println("Stack:  " + stack);
  
        // Verifying if the Stack is empty or not
        System.out.println("Is the Stack empty? "
                           + stack.isEmpty());
  
        // Clearing the Stack
        stack.clear();
  
        // Displaying the Stack
        System.out.println("Stack after clear(): "
                           + stack);
  
        // Verifying if the Stack is empty or not
        System.out.println("Is the Stack empty? "
                           + stack.isEmpty());
    }
}

输出：

Stack:  [Welcome, To, Geeks, 4, Geeks]
Is the Stack empty? false
Stack after clear(): []
Is the Stack empty? true

示例2

// Java code to illustrate isEmpty()
import java.util.*;
  
public class StackDemo {
    public static void main(String args[])
    {
        // Creating an empty Stack
        Stack<Integer> stack = new Stack<Integer>();
  
        // Displaying the Stack
        System.out.println("Stack:  " + stack);
  
        // Verifying if the Stack is empty or not
        System.out.println("Is the Stack empty? "
                           + stack.isEmpty());
    }
}

输出：

Stack:  []
Is the Stack empty? true