[Java] Ordered Fractions

/* Use the slash-star style comments or the system won't see your
   identification information */
/*
ID: lincans1
LANG: JAVA
TASK: frac1
*/
import java.io.*;
import java.util.*;

class Fraction implements Comparable<Fraction> {
    
    
	private int molecular;
	private int denominator;
	public int getMolecular() {
    
    
		return molecular;
	}
	public int getDenominator() {
    
    
		return denominator;
	}
	public Fraction(int molecular, int denominator) {
    
    
		this.molecular = molecular;
		this.denominator = denominator;
	}
	public int compareTo (Fraction that) {
    
    
		double ans = 1.0 * this.molecular / this.denominator - 1.0 * that.molecular / that.denominator;
		return ans > 0 ? 1 : ans < 0 ? -1 : 0;
	}
	public String toString() {
    
    
		return molecular + "/" + denominator;
	}
}

public class frac1 {
    
    

	public frac1() throws IOException {
    
    
		// Use BufferedReader rather than RandomAccessFile; it's much faster
		BufferedReader f = new BufferedReader(new FileReader("frac1.in"));
		PrintWriter out = new PrintWriter(new BufferedWriter(new FileWriter("frac1.out")));

		// Use StringTokenizer vs. readLine/split -- lots faster
		StringTokenizer st = new StringTokenizer(f.readLine());

	    int N = Integer.parseInt(st.nextToken());
	    Set<Fraction> fractions = new TreeSet<>();
	    Set<Double> set = new HashSet<>();
	    for (int i = 0; i <= N; i++) {
    
    
	    	for (int j = i; j <= N; j++) {
    
    
	    		if (j == 0) continue;
	    		double frac = (double)i / (double)j;
	    		if (!set.contains(frac)) {
    
    
	    			set.add(frac);
	    			fractions.add(new Fraction(i, j));
	    		}
	    	}
	    }
	    for (Fraction fraction : fractions) {
    
    
	    	out.println(fraction);
	    }
	    out.close();                                  // close the output file
	}
	
	public static void main (String [] args) throws IOException {
    
    
		new frac1();
	}
}