java - 指定抛出 IOException

Question

谁能帮我解决我的问题。我是 Java 编程的初学者。以前，当我没有声明抛出IOException时，它给了我一个错误:

Exception in thread "main" java.lang.RuntimeException: Uncompilable source code - unreported exception java.io.IOException; must be caught or declared to be thrown

程序如下所示:

import java.io.*;

public class addition {
    public static void main(String array[])throws IOException
    {
        InputStreamReader i = new InputStreamReader(System.in);
        BufferedReader b = new BufferedReader(i);
        System.out.println("Enter first number : ");
        int a1 = Integer.parseInt(b.readLine());
          System.out.println("Enter second number : ");
        int a2 = Integer.parseInt(b.readLine());
        int sum = a1 + a2 ;
        System.out.println("addition"+sum);
    }

}

Answer 1

如果在尝试从输入流读取时发生 I/O 失败，BufferedReader 函数 readLine() 会抛出 IOException。在 Java 中，必须使用 try catch 语句来处理出现的异常:

import java.io.*;

public class addition {
public static void main(String array[])throws IOException
{
    InputStreamReader i = new InputStreamReader(System.in);
    BufferedReader b = new BufferedReader(i);
    System.out.println("Enter first number : ");

    // Attempt to read in user input.
    try {
        int a1 = Integer.parseInt(b.readLine());
        System.out.println("Enter second number : ");
        int a2 = Integer.parseInt(b.readLine());
        int sum = a1 + a2 ;
        System.out.println("addition"+sum);
    }

    // Should there be some problem reading in input, we handle it gracefully.
    catch (IOException e) {
        System.out.println("Error reading input from user. Exiting now...");
        System.exit(0);
    }
}
}