foo.java

import java.io.FileNotFoundException;
import java.io.PrintWriter;
import java.util.Random;
import java.util.stream.IntStream;

public class Foo {

  public static void main(String[] args) throws FileNotFoundException {
    IntStream range = IntStream.range(1, 100_000);

    PrintWriter datafile = new PrintWriter("datafile");
    range.map(i -> new Random(i).nextInt(100))
        .forEach(datafile::println);

    datafile.close();
  }

}

plot.gnuplot

set term png
set output "hist.png"
binwidth=1
bin(x,width)=width*floor(x/width)

plot 'datafile' using (bin($1,binwidth)):(1.0) smooth freq with boxes