public interface FileHandler
{
    public void openFileHandler(String fileName);
    public void closeFileHandler();

    public String readLine();
    public String [] parseLine(String line);
    public String [] checkLine(String line[]);

    public void incrementLineCount();
    public void incrementLineSuccessCount();
    public void incrementLineErrorCount();

    public int getLineCount();
    public int getLineSuccessCount();
    public int getLineErrorCount();
}

interface FileHandler {
  public void openFileHandler(String fileName);
  public void closeFileHandler();
}

abstract class AbstractFileHandler implements FileHandler {
  ...
  protected abstract void incrementLineCount();
  protected abstract void incrementLineSuccessCount();
  protected abstract void incrementLineErrorCount();
}

class ConcreteFileHandler extends AbstractFileHandler {
  ...
}