java - 对原始堆栈实现泛型

Question

我对如何在java中实现泛型一无所知，所以我希望我能得到一些帮助，将我的堆栈的原始实现(如下)变成一个使用泛型的程序(假设可以只改变一些的事情，而不是如何编写完全不同的程序)。

下面是我的代码:

import java.io.*;
import java.util.*;

public class LinkedListStack {

    public static Stack<Integer> stk = new Stack<Integer>();
    public static int min, push, top;

    public static void main(String[] args) {        

        //initialize random integer generator
        Random rand = new Random();

        System.out.println("Stack empty --> top = null, min = null");
        stackPush(rand.nextInt(50));

        //first value in the stack is the minimum until a smaller integer is pushed
        min = stk.peek();

        stackPush(rand.nextInt(50));
        stackPush(rand.nextInt(50));
        stackPop();
        stackPush(rand.nextInt(50));
        stackPush(rand.nextInt(50));
        stackPush(rand.nextInt(50));
        stackPush(rand.nextInt(50));
        stackPop();
        stackPop();
        stackPop();
        stackPop();
        stackPop();
        stackPop();
        stackPop();

        if (!stk.isEmpty()) {
            System.out.print("\nFinal stack: ");
            for(int x : stk) {
                System.out.print(x + " ");
            }
        } else {
            System.out.print("\nStack is empty!");
        }

        System.out.println();
    }

    public static int stackPush(int pushInt) {
        try {
            stk.push(pushInt);
            if (stk.peek() < min) {
                min = stk.peek();
            }
            top = stk.peek();
            System.out.println("Push " + pushInt + " --> top = " + top +  ", min = " + min);

        } catch (EmptyStackException e){
            System.out.println("ERROR");
        }

        return pushInt;
    }

    public static void stackPop() {
        try {
            stk.pop();
            if (stk.peek() < min) {
                min = stk.peek();
            }
            top = stk.peek();
            System.out.println("Pop --> top = " + top +  ", min = " + min);

        } catch (EmptyStackException e) {
            System.out.println("Stack already empty!");
        }
    }
}

Answer 1

首先，您的类不应该是静态的来完成此任务。它也不应该通过公共(public)字段或通过诸如 LinkListStack

之类的命名来公开其底层实现

相反，您可以创建一个类，例如

class MyStack<E> {    
    private final Stack<E> wrapped = new Stack<E>();

    public void push(E element) {
        wrapped.push(e);
    }

    public E pop() {
        return wrapped.pop();
    }
}


public class Program {

     public static void main(String[] args) {        

     System.out.println("Stack empty --> top = null, min = null");

     MyStack<String> stack = new MyStack<>();

     stack.push("hello");

     stack.push("world");
}

注意:Java 有一个内置的堆栈，重新发明轮子是一种不好的做法，除非纯粹是为了教育/探索性编程。这个内置堆栈实际上用于提供底层包装值，该值构成了我们实现的支柱。