Java Stack lastIndexOf()方法与实例

Java.util.Stack.lastIndexOf(Object element)方法用于检查和查找某个特定元素在堆栈中的出现。如果该元素在堆栈中存在，那么lastIndexOf()方法返回该元素最后出现的索引，否则返回-1。这个方法是用来查找一个特定元素在堆栈中的最后出现。

语法

Stack.lastIndexOf(Object element)

参数： 参数元素的类型是堆栈。它指的是需要检查其最后出现的元素。

返回值： 该方法返回该元素在Stack中最后出现的位置。如果该元素在Stack中不存在，那么该方法返回-1。返回值是整数类型的。

以下程序说明了Java.util.Stack.lastIndexOf()方法。

程序1 :

// Java code to illustrate lastIndexOf()
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 in the Stack
        stack.add("Geeks");
        stack.add("for");
        stack.add("Geeks");
        stack.add("10");
        stack.add("20");
  
        // Displaying the Stack
        System.out.println("Stack: " + stack);
  
        // The last position of an element is returned
        System.out.println("Last occurrence of Geeks is at index: "
                           + stack.lastIndexOf("Geeks"));
        System.out.println("Last occurrence of 10 is at index: "
                           + stack.lastIndexOf("10"));
    }
}

输出：

Stack: [Geeks, for, Geeks, 10, 20]
Last occurrence of Geeks is at index: 2
Last occurrence of 10 is at index: 3

示例2

// Java code to illustrate lastIndexOf()
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 in the Stack
        stack.add(10);
        stack.add(22);
        stack.add(3);
        stack.add(10);
        stack.add(20);
  
        // Displaying the Stack
        System.out.println("Stack: " + stack);
  
        // The last position of an element is returned
        System.out.println("Last occurrence of 10 is at index: "
                           + stack.lastIndexOf(10));
        System.out.println("Last occurrence of 20 is at index: "
                           + stack.lastIndexOf(20));
    }
}

输出：

Stack: [10, 22, 3, 10, 20]
Last occurrence of 10 is at index: 3
Last occurrence of 20 is at index: 4