小编Abd*_*dir的帖子

我完全是java的菜鸟。刚开始。一些请帮助我获得此代码。试图编写代码进行计算，但显示找不到符号。

import java.util.Scanner;

public class Cal {
    public static void main(String args[]) {
        int a, b, r;
        String op;
        System.out.print("Choose one : add, sub, mul, div ");
        Scanner input = new Scanner(System.in);
        op = input.nextLine();
        System.out.print("Enter the value : ");
        Scanner val = new Scanner(System.in);
        a = val.nextInt();
        b = val.nextInt();
        if (op == add) {
            r = a + b;
            System.out.println(r);
        } else if (op == sub) {
            r = a - b;
            System.out.println(r);
        } else if (op == …