Java实现用Stack实现基础的计算器

package main.java;
import java.util.Scanner;
import java.util.Stack;

public class evaluate {
    public static Stackstack=new Stack();
    public static Stackstack1=new Stack();
    public static boolean isNumeric(char c){
        if((c>='0'&&c<='9')||c=='.'){
            return true;
        }else{
            return false;
        }
    }
    public static void cal(){
        double temp=stack.peek();
        stack.pop();
        double temp2=stack.peek();
        stack.pop();
        if(stack1.peek()=='+'){
            temp2+=temp;
            stack.push(temp2);
        }
        if(stack1.peek()=='-'){
            temp2-=temp;
            stack.push(temp2);
        }        if(stack1.peek()=='*'){
            temp2*=temp;
            stack.push(temp2);
        }
        if(stack1.peek()=='/'){
            try{
                temp2/=temp;
                stack.push(temp2);
            }catch (Exception e){
                e.printStackTrace();
            }
        }
        stack1.pop();
    }

    public static void main(String[] args) {

        Scanner sc=new Scanner(System.in);
        String s=sc.nextLine();
        StringBuffer num=new StringBuffer("");
        char c;
        for(int i=0;i=1&&s.charAt(i-1)!=')'){
                        double n = Double.parseDouble(num.toString());
                        stack.push(n);
                    }

                    if (c == ')') {
                        while (stack1.peek() != '(') {
                            cal();
                        }
                        stack1.pop();
                    }
                    if (c == '+' || c == '-') {
                        if (!stack1.isEmpty() && stack1.peek() != '(') {
                            cal();
                        }
                        stack1.push(c);
                    }
                    if (c == '*' || c == '/') {
                        stack1.push(c);
                    }
                    num.delete(0, num.length());

                }
            }
        }
        if(!stack1.isEmpty()){
            cal();
        }
        System.out.println(stack.peek());

    }
}