Java Stack contains()方法及实例

java.util.Stack.contains()方法是用来检查一个特定的元素是否存在于堆栈中。因此，基本上它是用来检查一个堆栈是否包含任何特定的元素。

语法

Stack.contains(Object element)

参数： 这个方法需要一个强制性的参数元素，它的类型是Stack。这是需要测试的元素，如果它在Stack中存在或不存在。

返回值： 如果该元素存在于Stack中，该方法返回True，否则返回False。

以下程序说明了Java.util.Stack.contains()方法。

程序1 :

// Java code to illustrate contains()
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);
  
        // 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<Integer> stack = new Stack<Integer>();
  
        // 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