java.util.Stack.contains()方法用于检查堆栈中是否存在特定元素。因此，本质上，它用于检查Stack是否包含任何特定元素。

用法:

Stack.contains(Object element)

参数：此方法采用了Stack类型的必需参数element 。如果堆栈中不存在此元素，则需要对其进行测试。

返回值：如果元素存在于堆栈中，则此方法返回True，否则返回False。

以下示例程序旨在说明Java.util.Stack.contains()方法：

示例1:

// Java code to illustrate contains()

import java.util.*;

public class StackDemo {

public static void main(String args[])

{

// Creating an empty Stack

Stack stack = new Stack();

// 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);

// Check for "Geeks" in the Stack

System.out.println("Does the Stack contains 'Geeks'? "

+ stack.contains("Geeks"));

// Check for "4" in the Stack

System.out.println("Does the Stack contains '4'? "

+ stack.contains("4"));

// Check if the Queue contains "No"

System.out.println("Does the Stack contains 'No'? "

+ stack.contains("No"));

}

}

输出：

Stack: [Welcome, To, Geeks, 4, Geeks]

Does the Stack contains 'Geeks'? true

Does the Stack contains '4'? true

Does the Stack contains 'No'? false

示例2:

// Java code to illustrate contains()

import java.util.*;

public class StackDemo {

public static void main(String args[])

{

// Creating an empty Stack

Stack stack = new Stack();

// Use add() method to add elements into the Stack

stack.add(10);

stack.add(15);

stack.add(30);

stack.add(20);

stack.add(5);

// Displaying the Stack

System.out.println("Stack: " + stack);

// Check for "Geeks" in the Stack

System.out.println("Does the Stack contains 'Geeks'? "

+ stack.contains("Geeks"));

// Check for "4" in the Stack

System.out.println("Does the Stack contains '4'? "

+ stack.contains("4"));

// Check if the Stack contains "No"

System.out.println("Does the Stack contains 'No'? "

+ stack.contains("No"));

}

}

输出：

Stack: [10, 15, 30, 20, 5]

Does the Stack contains 'Geeks'? false

Does the Stack contains '4'? false

Does the Stack contains 'No'? false