Recursively counts the lines of all java files in a directory

linecountsofjavafiles.java

import java.io.File;
import java.io.IOException;
import java.nio.file.Files;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.List;
import java.util.Objects;

/**
 * @author msc
 * @since 18.06.2018
 */
public class CheckLineCounts
{
  public static void main( final String[] args )
  {
    final File currentDir = new File( "Path..." );

    listLineCounts( Arrays.asList( currentDir.listFiles() ) );
  }

  private static void listLineCounts( final Collection<File> files )
  {
    files
        .stream()
        //Get all files recursively
        .map( file -> recursiveFiles( file ) )
        //Combine all lists
        .reduce( ( filesOne, filesTwo ) ->
        {
          filesOne.addAll( filesTwo );
          return filesOne;
        } )
        //Since we can't be arsed to check for null or so
        .orElse( new ArrayList<>() )
        //Stream of the combined list
        .stream()
        //Only java files
        .filter( file -> file.getName().endsWith( ".java" ) )
        //Get line count of every file
        .map( CheckLineCounts::getLineInfo )
        //Filter out null values
        .filter( Objects::nonNull )
        //distinct entries only
        .distinct()
        //sort from smallest to biggest
        .sorted( ( pairOne, pairTwo ) -> pairOne.getSize().compareTo( pairTwo.getSize() ) )
        //print out information to console
        .forEach( System.out::println );
  }

  private static List<File> recursiveFiles( final File file )
  {
    if ( not( file.isDirectory() ) )
    {
      return Arrays.asList( file );
    }

    final List<File> files = new ArrayList<>();
    for ( final File childFile : file.listFiles() )
    {
      files.addAll( recursiveFiles( childFile ) );
    }

    return files;
  }

  private static boolean not( final boolean b )
  {
    return !b;
  }

  private static LongFile getLineInfo( final File file )
  {
    try
    {
      return new LongFile( file.getName(), Files.readAllLines( file.toPath() ).size() );
    }
    catch ( @SuppressWarnings( "unused" ) final IOException exception )
    {
      return null;
    }
  }

  private static class LongFile
  {
    private final String  file;
    private final Integer size;

    public LongFile( final String file, final Integer size )
    {
      super();
      this.file = file;
      this.size = size;
    }

    @Override
    public boolean equals( final Object obj )
    {
      return file.equals( ((LongFile) obj).file );
    }

    /**
     * @return the size
     */
    public Integer getSize()
    {
      return size;
    }

    @Override
    public String toString()
    {
      return size + " lines in " + file;
    }

    @Override
    public int hashCode()
    {
      return super.hashCode();
    }
  }
}