Java Stack peek()用法及代码示例 |
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Java中的java.util.Stack.peek()方法用于检索或获取Stack的第一个元素或位于Stack顶部的元素。检索到的元素不会被删除或从堆栈中删除。 用法: STACK.peek()参数：该方法不带任何参数。 返回值：该方法返回堆栈顶部的元素，如果堆栈为空，则返回NULL。 异常：如果堆栈为空，则该方法引发EmptyStackException。 以下程序说明了java.util.Stack.peek()方法： 示例1: // Java code to illustrate peek() function import java.util.*; public class StackDemo { public static void main(String args[]) { // Creating an empty Stack Stack STACK = new Stack(); // Use push() to add elements into the Stack STACK.push("Welcome"); STACK.push("To"); STACK.push("Geeks"); STACK.push("For"); STACK.push("Geeks"); // Displaying the Stack System.out.println("Initial Stack: " + STACK); // Fetching the element at the head of the Stack System.out.println("The element at the top of the" + " stack is: " + STACK.peek()); // Displaying the Stack after the Operation System.out.println("Final Stack: " + STACK); } } 输出： Initial Stack: [Welcome, To, Geeks, For, Geeks] The element at the top of the stack is: Geeks Final Stack: [Welcome, To, Geeks, For, Geeks]示例2: // Java code to illustrate peek() function import java.util.*; public class StackDemo { public static void main(String args[]) { // Creating an empty Stack Stack STACK = new Stack(); // Use push() to add elements into the Stack STACK.push(10); STACK.push(15); STACK.push(30); STACK.push(20); STACK.push(5); // Displaying the Stack System.out.println("Initial Stack: " + STACK); // Fetching the element at the head of the Stack System.out.println("The element at the top of the" + " stack is: " + STACK.peek()); // Displaying the Stack after the Operation System.out.println("Final Stack: " + STACK); } } 输出： Initial Stack: [10, 15, 30, 20, 5] The element at the top of the stack is: 5 Final Stack: [10, 15, 30, 20, 5]
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