program.java

Java Class, which implements Rational Numbers. Includes a simple test.

package dada;
public class program{
	public static void main(String [] args){
		Rational r = new Rational(2.5);
		System.out.println("r1= " + r.toString());
		Rational r2 = new Rational(42,10);
		System.out.println("r2= " + r2.toString());
		System.out.println("r2= " + r2.doubleValue());
		System.out.println("r2 invertiert= " + r2.invert().toString());
		System.out.println("r2 negiert= " + r2.negate().toString());
		System.out.println("r2 + r= " + r2.add(r).toString());
		System.out.println("r2 * r= " + r2.multiply(r).toString());
		System.out.println("r2 / r= " +r2.divide(r).toString());
		System.out.println("r2 - r= " +r2.subtract(r).toString());
	}

}
class Rational{
	private long zaehler;
	private long nenner;

	public Rational(){
		this.zaehler =0;
		this.nenner = 1;
	}
	public Rational(long z, long n){
		norm(z,n);
		//this.zaehler = z;
		//this.nenner = n;
	}
	public Rational(long a){
		this(a,1);
	}
	public Rational(double a){
		this((long)(a*100000000),100000000);
		//this.nenner =            100000000;
	}
	public String toString(){
		return "(" + this.zaehler + ")/(" + this.nenner + ")";
	}
	public double doubleValue(){
		return ((double)this.zaehler/(double)this.nenner);
	}
	public Rational negate(){
		return new Rational(-this.zaehler,this.nenner);
	}
	public Rational invert(){
		return new Rational(this.nenner,this.zaehler);
	}
	public double getNumerator(){
		return this.zaehler;
	}
	public double getDenominator(){
		return this.nenner;
	}
	private long gcd(long a, long b){
		if(b==0){
			return a;
		}else{
			return gcd(b, a%b);
		}
	}
	private void norm(long z, long n){
		long dada = gcd(z, n);
		//this(z/dada, n/dada);
		this.zaehler= z/dada;
		this.nenner = n/dada;
	}
	public Rational multiply (Rational z){
		return new Rational((long)(this.zaehler * z.getNumerator()),(long)(this.nenner * z.getDenominator()));
	}
	public Rational add (Rational z){
		return new Rational((long)(this.zaehler*z.getDenominator() + z.getNumerator()*this.nenner),(long)(this.nenner * z.getDenominator()));
	}
	public Rational subtract (Rational z){
		return add(z.negate());
	}
	public Rational divide (Rational z){
		return multiply(z.invert());
	}

}