需要幫助，在我的Java計算器

Question

我最近開始學習java，我試圖編程計算器，但它給了我錯誤（我不明白爲什麼會發生）。

PS：對不起我的英文不好

package pkg2; 

import java.util.Scanner; 

public class Main { 
    public static void main(String[] args) { 
     Scanner reader = new Scanner(System.in); 
     System.out.println("Write a number: "); 
     int first = reader.nextInt(); 
     System.out.println("Write another number: "); 
     int second = reader.nextInt(); 
     System.out.println("Write an operator: "); 
     char operator = reader.nextInt(); 
     if(operator == '+') { 
      System.out.println(first + second); 
     } 
     else if(operator == '-') { 
      System.out.println(first - second); 
     } 
     else if(operator == '*') { 
      System.out.println(first * second); 
     } 
     else if(operator == '/') { 
      System.out.println(first/second); 
     } 
    } 
} 

的錯誤是：

Answer 1

當您提示操作，你想，而不是一個char讀取INT， 。以下是你應該怎麼做：

package pkg2; 

import java.util.Scanner; 

public class Main { 
    public static void main(String[] args) { 
     Scanner reader = new Scanner(System.in); 
     System.out.println("Write a number: "); 
     int first = reader.nextInt(); 
     System.out.println("Write another number: "); 
     int second = reader.nextInt(); 
     System.out.println("Write an operator: "); 
     char operator = reader.next().charAt(0); 
     if(operator == '+') { 
      System.out.println(first + second); 
     } 
     else if(operator == '-') { 
      System.out.println(first - second); 
     } 
     else if(operator == '*') { 
      System.out.println(first * second); 
     } 
     else if(operator == '/') { 
      System.out.println(first/second); 
     } 
    } 
}