Question

目标不是解析实际整数而是刺激A + B * C，例如输出ABC * +

我不是在使用泛型，而是使用自制的Stack类。我总是以一个错误的结束异常结束，引用peek（）方法。我已经尝试了很长一段时间跟踪它，并且无法真正解决出错的问题。

import java.util.*;

public class Stack {

    private char[] arr;
    private int maxsize;
    private int top = -1;

    public Stack(int size) {
        maxsize = size;
        arr = new char[maxsize];
    }

    public void push(char x) {
        arr[++top] = x;

    }

    public char pop() {
        return arr[top--];
    }

    public char peek() {
        return arr[top];
    }

    public int size() {
        return top + 1;
    }

    public boolean isEmpty() {
        return (size() > 0);
    }

    public boolean isFull() {
        return top == maxsize - 1;
    }

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        String text = sc.next();
        Stack medo = new Stack(99);
        doParse(text);

    }

    public static void doParse(String text) {

        Stack parse = new Stack(900);
        for (int i = 0; i < text.length(); i++) {
            char ch = text.charAt(i);
            switch (ch) {
                case '-':
                case '+':
                    if (parse.isEmpty()) {
                        parse.push(ch);
                    } else {
                        while (!parse.isEmpty()) {
                            System.out.print(parse.pop());
                        }

                    }
                    break;
                case '*':
                case '/':
                    if (parse.isEmpty() || parse.peek() == '+'
                            || parse.peek() == '-') {
                        parse.push(ch);
                    } else {
                        while (!parse.isEmpty()) {
                            System.out.print(parse.pop());
                        }
                    }
                    ;
                    break;
                default:
                    System.out.print(ch);

            }
        }
    }

}

Answer 1

你的isEmpty()方法与它应该做的相反。这导致你偷看空堆栈

public boolean isEmpty() {
    return (size() > 0);
}

应该是

public boolean isEmpty() {
    return (size() <= 0);
}

使用堆栈解析算术字符

1 个答案: