*** Class Fraction is incomplete and mutable, make it complete and immutable! *** public class Fraction implements Cloneable, Comparable { private int numerator, denominator; public Fraction(int numerator){ this(numerator, 1); } public Fraction(int numerator, int denominator){ this.numerator = numerator; this.denominator = denominator; reduce(); } public int getNumerator(){ return numerator; } public int getDenominator(){ return denominator; } public void setNumerator(int n){ numerator = n; } public void setDenominator(int d){ denominator = d; } public Fraction clone(){ return null; } public int compareTo(Fraction other){ return 0; } @Override public boolean equals(Object o){ return false; } @Override public String toString(){ if (denominator == 1) { return String.valueOf(numerator); } else { return numerator + "/" + denominator; } } //This add method is currently mutable public void add(Fraction other){ numerator = numerator * other.denominator + other.numerator * denominator; denominator = denominator * other.denominator; reduce(); // private helper to reduce fraction } private void reduce(){ int gcd = gcd(numerator, denominator); this.numerator = numerator /gcd; this.denominator = denominator /gcd; } public void subtract(Fraction other){ } public void multiply(Fraction other){ } public void divide(Fraction other){ } //this method returns greatest common divisor of x and y //-6 and 4 is 2 private static int gcd(int x, int y){ if( y == 0 ) return Math.abs(x); else return gcd(y, x % y); } }