Sometimes we'll get this error "editor does not contain a main type" that is not a serious problem. Just because your jave code has a package declaration, like this :

package ps3.test;

import java.io.*;
import java.util.*;

import ps3.graph.*;

and take a main function that you try to run it in this file

public static void main(String args[]) {

Solution :
Just move your package folder to below src, like this :