Eclipse源代码错误

Question

while I was studying Stanford CS 106 AI had to download acm.jar file. I have imported and everything worked fine till I wanted to run a simple program from the source code I got in video. The error down below:

( http://i.imgur.com/5NcUj2S.png?1 )

When I want to run:

http://imgur.com/E042rHs

and the source code:

import acm.program.*;


    public class Add2Doubles extends ConsoleProgram {
        public void run() {
           println("This program adds two numbers.");
           int n1 = readInt("Enter n1: ");
           int n2 = readInt("Enter n2: ");
           int total = n1 + n2;
           println("The total is " + total + ".");
        }
     }

Thanks in advance for your helps. I'm on lecture 5.

Answer 1

Your javafile is not in your sources directory and hence not on your build-path.

Try moving Add2Doubles.java to your src folder.

edit: Thanks to the comment I thought about another suggestion: You might have to move your acm directory to the src folder as well (as indeed, that is where eclipse will look for your source files).

Answer 2

The error explains it well enough to me? You've not got any sources! I believe that URLClassLoader is part of the default java runtime libraries so you can need to get the sources from the Java website.