06.数组模拟栈-简易计算器

/**
 *  数组模拟栈-简易计算器
 */
public class ArrayStackDemo {
    public void calculate(String s){
        //数字栈
        ArrayStack numStack = new ArrayStack(10);
        //符号栈
        ArrayStack operStack = new ArrayStack(10);
        int index = 0;
        char c;
        int res = 0;
        int num1 = 0;
        int num2 = 0;
        String num = "";
        do {
            c = s.substring(index, index + 1).charAt(0);
            //是符号
            if (isOper(c)) {
                if (operStack.isEmpty()) {
                    operStack.push(c);
                } else { //符号栈不为空,如果栈中的优先级大就取数字栈的2个进行运算
                    if (priority(c) <= priority(operStack.peek())) {
                        num2 = numStack.pop();
                        num1 = numStack.pop();
                        res = cal(num1, num2, operStack.pop());
                        numStack.push(res);
                        operStack.push(c);
                    } else {
                        operStack.push(c);
                    }
                }
            } else {
                num = num + c;
                if (index == s.length()-1){
                    numStack.push(Integer.parseInt(num));
                }else if (isOper(s.substring(index+1, index+2).charAt(0))){
                    numStack.push(Integer.parseInt(num));
                    num = "";
                }
            }
            System.out.print(c);
            index++;
        } while (index < s.length());

        while (true){
            if (!operStack.isEmpty()){
                num2 = numStack.pop();
                num1 = numStack.pop();
                res = cal(num1, num2, operStack.pop());
                numStack.push(res);
            }else {
                break;
            }
        }
        res = numStack.pop();
        System.out.println("="+res);

    }
    // * / + - 运算符优先级
    private int priority(int oper){
        if (oper=='*'||oper=='/'){
            return 1;
        }
        if (oper=='+'||oper=='-'){
            return 0;
        } else {
            return -1;
        }
    }
    // 判断是不是* / + -
    private boolean isOper(int val){
        return val=='+'||val=='-'||val=='*'||val=='/';
    }
    private static int cal(int num1, int num2, int oper){
        int res = 0;
        switch (oper){
            case '+':
                res = num1 + num2;
                break;
            case '-':
                res = num1 - num2;
                break;
            case '*':
                res = num1 * num2;
                break;
            case '/':
                res = num1 / num2;
                break;
            default:
                break;
        }
        return res;
    }

    public static void main(String[] args){
//        ArrayStack stack = new ArrayStack(3);
//        stack.push(1);
//        stack.push(2);
//        stack.push(3);
//        stack.push(4);
//        stack.list();
//        stack.pop();
//        stack.list();
//        stack.pop();
//        stack.pop();
//        stack.pop();

        new ArrayStackDemo().calculate("11+1*1");
        new ArrayStackDemo().calculate("10+11-1");
        new ArrayStackDemo().calculate("10+10/10");
        new ArrayStackDemo().calculate("10+10+10");


    }
}
class ArrayStack{
    private int maxsize;
    private int[] stack;
    private int top = -1;

    public ArrayStack(int maxsize) {
        this.maxsize = maxsize;
        stack = new int[maxsize];
    }
    //栈满
    public boolean isFull(){
        return top == maxsize-1;
    }
    //栈空
    public boolean isEmpty(){
        return top == -1;
    }
    //入栈
    public void push(int i){
        if (isFull()){
            System.out.println("栈满～");
            return;
        }
        top++;
        stack[top] = i;
    }
    //出栈
    public int pop(){
        if (isEmpty()){
            System.out.println("栈空～");
            return -1;
        }
        int i = stack[top];
        top--;
        return i;
    }
    public int peek(){
        if (isEmpty()){
            System.out.println("栈空～");
            return -1;
        }
        return stack[top];
    }
    public void list(){
        if (isEmpty()){
            System.out.println("栈空～");
            return;
        }
        for (int i = top; i >= 0; i--) {
            System.out.print("stack["+i+"]="+stack[i]+" ");
        }
        System.out.println();
    }
}