从外部类向主函数中提供用户输入

Question

我有两个班级，

public class ClassOne {

static Scanner sc;
static int a,b,c,d;

public static void main(String [] args){
    sc = new Scanner(System.in);

    System.out.println("Input 4 numbers, one after another");
    a = sc.nextInt();
    b = sc.nextInt();
    c = sc.nextInt();
    d = sc.nextInt();

    System.out.println(a + b + c + d);
}

}


public class ClassTwo {

public static void main(String [] args){
    ClassOne.main(null);

    // I want to programatically input 
    // numbers into the Scanner from ClassOne,
    // and run the program.

    }
}

我从ClassTwo运行main，并且必须将值（4个整数）输入System.in中的Scanner。我该怎么做呢？谢谢。

Answer 1

按System.in将System.setIn(<your_input_stream>)设置为另一个InputStream，然后从ClassTwo

写入该输入流

public class ClassTwo {    
    public static void main(String [] args){
        InputStream replacedIn = new ByteArrayInputStream("1\n2\n3\n4\n".getBytes());
        System.setIn(replacedIn);
        ClassOne.main(null);
    }
}