[SOLVED] In cannot be resolved to a type

In cannot be resolved to a type

I am following Prinston's course Algorithms, Part I. As I came from .NET and just started to use Java, I have some issue with a piece of Java code and I can not find any related information. They provide with a code which I can use for reading a text file:

public static void main(String[] args) {

    In in = new In(args[0]);
    int n = in.readInt();
    ...
}

Exception thrown:

In cannot be resolved to a type

What is this In? Should I import some package or what should I do?

The whole code and description can be also seen here: http://coursera.cs.princeton.edu/algs4/assignments/collinear.html

Solution

You need algs4, provided by Princeton as well. When it's in the classpath, add

import edu.princeton.cs.algs4.In;

If that's the only class, you could use the source of In.java. But I doubt that's allowed on Coursera: when you submit code, it will probably be compiled on the server with algs4.jar in the classpath, so you should really use that one and not your own code.