java 栈

package testjavapro;
import java.util.*;
 
public class testjava {
 
    static void showpush(Stack<Integer> st, int a) {
        st.push(new Integer(a));
        System.out.println("push(" + a + ")");
        System.out.println("cur stack: " + st);
    }
 
    static void showpop(Stack<Integer> st) {
        System.out.print("pop -> ");
        Integer a = (Integer) st.pop();
        System.out.println(a);
        System.out.println("cur stack: " + st);
    }
 
    public static void main(String args[]) {
        Stack<Integer> st = new Stack<Integer>();
        System.out.println("stack: " + st);
        showpush(st, );
        showpush(st, );
        showpush(st, );
 
        showpop(st);
        showpop(st);
        showpop(st);
 
        try {
            showpop(st);
        } catch (EmptyStackException e) {
            System.out.println("empty stack");
        }
    }
}

输出

stack: []
push()
cur stack: []
push()
cur stack: [, ]
push()
cur stack: [, , ]
pop ->
cur stack: [, ]
pop ->
cur stack: []
pop ->
cur stack: []
pop -> empty stack