title: Eclipse error: "Editor does not contain a main type"
body: <p>I can't seem to run the following code in Eclipse. I do have a main method and this is the currently opened file. I even tried the "Run As" option but I keep getting this error: "editor does not contain a main type". What am I doing wrong here?</p>
  
  <pre><code> public class cfiltering {
  
      /**
       * @param args
       */
  
      //remember this is just a reference
      //this is a 2d matrix i.e. user*movie
      private static int user_movie_matrix[][];
  
      //remember this is just a reference
      //this is a 2d matrix i.e. user*user and contains
      //the similarity score for every pair of users.
      private float user_user_matrix[][]; 
  
  
      public cfiltering()
      {
          //this is default constructor, which just creates the following:
          //ofcourse you need to overload the constructor so that it takes in the dimensions
  
          //this is 2d matrix of size 1*1
          user_movie_matrix=new int[1][1];
          //this is 2d matrix of size 1*1
          user_user_matrix=new float[1][1];
      }
  
      public cfiltering(int height, int width)
      {
          user_movie_matrix=new int[height][width];
          user_user_matrix=new float[height][height];
      }
  
  
      public static void main(String[] args) {
          //1.0 this is where you open/read file
          //2.0 read dimensions of number of users and number of movies
          //3.0 create a 2d matrix i.e. user_movie_matrix with the above dimensions. 
          //4.0 you are welcome to overload constructors i.e. create new ones. 
          //5.0 create a function called calculate_similarity_score 
          //you are free to define the signature of the function
          //The above function calculates similarity score for every pair of users
          //6.0 create a new function that prints out the contents of user_user_matrix 
  
          try
          {
              //fileinputstream just reads in raw bytes. 
              FileInputStream fstream = new FileInputStream("inputfile.txt");
  
              //because fstream is just bytes, and what we really need is characters, we need
              //to convert the bytes into characters. This is done by InputStreamReader. 
              BufferedReader br = new BufferedReader(new InputStreamReader(fstream));
              int numberOfUsers=Integer.parseInt(br.readLine());
              int numberOfMovies=Integer.parseInt(br.readLine());
  
              //Now you have numberOfUsers and numberOfMovies to create your first object. 
              //this object will initialize the user_movie_matrix and user_user_matrix.
  
              new cfiltering(numberOfUsers, numberOfMovies);
  
              //this is a blankline being read
              br.readLine();
              String row;
              int userNo = 0;
              while ((row = br.readLine()) != null)   
              {
                  //now lets read the matrix from the file
                  String allRatings[]=row.split(" ");
                  int movieNo = 0;
                  for (String singleRating:allRatings)
                  {
                      int rating=Integer.parseInt(singleRating);
                      //now you can start populating your user_movie_matrix
                      System.out.println(rating);
                      user_movie_matrix[userNo][movieNo]=rating;
                      ++ movieNo;
                  }
                  ++ userNo;
              }
          }
          catch(Exception e)
          {
              System.out.print(e.getMessage());
          }
      }
  
  }
  </code></pre>