Java Stack push()方法

Java.util.Stack.push(E element)方法用于将一个元素推入堆栈。该元素会被推到堆栈的顶部。

语法

STACK.push(E element)

参数： 该方法接受一个Stack类型的参数element，指的是要被推入堆栈的元素。

返回值： 该方法返回所传递的参数。 它也接受空值，不像ArrayDeque.push()在做同样事情时抛出java.lang.NullPointerException。

下面的程序说明了Java.util.Stack.push()方法。

程序1： 将字符串元素添加到堆栈中。

// Java Code to illustrate push() Method
 
import java.util.*;
 
// Main class
public class StackDemo {
 
    // Main driver method
    public static void main(String args[])
    {
        // Creating an empty Stack
        Stack& lt;
        String& gt;
        STACK = new Stack& lt;
        String& gt;
        ();
 
        // Adding elements into the stack
        // using push() method
        STACK.push(" Welcome & quot;);
        STACK.push(" To & quot;);
        STACK.push(" Geeks & quot;);
        STACK.push(" For & quot;);
        STACK.push(" Geeks & quot;);
 
        // Displaying the Stack
        System.out.println(" Initial Stack
                           : "
                           + STACK);
 
        // Pushing elements into the stack
        STACK.push(" Hello & quot;);
        STACK.push(" World & quot;);
 
        // Displaying the final Stack
        System.out.println(" Final Stack
                           : "
                           + STACK);
    }
}

输出

Initial Stack: [Welcome, To, Geeks, For, Geeks]
Final Stack: [Welcome, To, Geeks, For, Geeks, Hello, World]

程序2： 将整数元素添加到堆栈中。

// Java code to illustrate push() method
import java.util.*;
 
public class StackDemo {
    public static void main(String args[])
    {
        // Creating an empty Stack
        Stack<Integer> STACK = new Stack<Integer>();
 
        // Use push() to add elements into the Stack
        STACK.push(10);
        STACK.push(15);
        STACK.push(30);
        STACK.push(20);
        STACK.push(5);
        STACK.push(null);
 
        // Displaying the Stack
        System.out.println("Initial Stack: " + STACK);
 
        // Pushing elements into the Stack
        STACK.push(1254);
        STACK.push(4521);
 
        // Displaying the final Stack
        System.out.println("Final Stack: " + STACK);
    }
}

输出

Initial Stack: [10, 15, 30, 20, 5]
Final Stack: [10, 15, 30, 20, 5, 1254, 4521]