我不知道如何通过 windows 命令提示符输入

Question

I made a simple program on java:

public class HelloWorld {

    public static void main(String[]args) {
        System.out.print(" Hello World");
        int n=Integer.parseInt(args[0]);
        StdOut.println();
        StdOut.print(n);
    }
}

When I run the program through windows command prompt it just prints "Hello World" and the program ends, with no error messages, not waitting for me to input the integer. I don't know what I do wrong. Is there any trick I don't know?

Answer 1

Think of why you are passing a string array, called args, into your program. Perhaps for something like arguments ?

That is an array of arguments passed into your program as strings, which is whatever follows in on the command. If the zeroth argument does not work, then try the first (args[1])

Try this

java hello 23

This passes 23 into the program as a string. Integer.parseInt(args[0]) parses it as an integer, and then the other lines display it. Try this and come back if it still fails.

On another note - this is fairly basic and many would expect you read each line and understand what it does before coding and running it. It's tempting to copy from StackOverflow and forget about it, but its not a good way to learn. One day you will end up running sudo rm -rf / without thinking twice ;)