Can you implement and override the list.sort () method to sort the list of rational numbers?

Question

So, I was asked the following problem:

Write a program that creates a list of rationals and sorts them with increasing order. Use the appropriate methods from the Framework Collections classes to sort the items in ascending order.

I created a Rational class to represent rational numbers, and I also compiled a list of Rational random numbers. But it’s hard for me to understand how to implement a list sorting method. Here are the code samples before I go further:

public class Rational implements Comparable<Rational> {
private int num;
private int denom;
private int common;

// Default constructor initialises fields
public Rational() throws IllegalNumDenomException {
    setNum(1);
    setDenom(2);
}

// Constructor sets fields with given parameters
public Rational(int num, int denom) throws IllegalNumDenomException {
    common = gcd(num,denom);
    setNum(num/common);
    setDenom(denom/common);
}

//Compares two rational numbers
public int compareTo(Rational rhs) {
    int tempNumerator = this.getNum() * rhs.getDenom();
    int tempNumeratorRhs = rhs.getNum() * this.getDenom();

    //Compares rationalised numerators and returns a corresponding value
    if (tempNumerator < tempNumeratorRhs) {
        return -1;
    } else if (tempNumerator > tempNumeratorRhs) {
        return 1;
    }
    return 0;
}

// Overriden toString method
public String toString() {
    return num + "/" + denom;
}

//Calculates the GCD of a fraction to simplify it later on
public int gcd(int x, int y) throws IllegalNumDenomException{
    while(x != 1){ //Prevents infinite loop as everything is divisible by 1
        if(x == y){
            return x;
        }
        else if(x>y){
            return gcd(x-y,y);
        }
        return gcd(x,y/x);
    }
    return 1;
}

public class RationalList {

public static void main(String[] args) throws IllegalNumDenomException {
    List<Rational> rationals = new ArrayList<Rational>();
    Random rand = new Random();
    int n = rand.nextInt(50) + 1;

    //Generates 9 random Rationals
    for(int i = 1; i<10; i++){
        rationals.add(new Rational(i,n));
        n = rand.nextInt(50) + 1;
    }

    System.out.println("Original Order: " + rationals.toString());
    sort(rationals);
    System.out.println(rationals);
}

public static List<Rational> sort(List<Rational> rationals){
    //Use compareTo method inside a loop until list is sorted

    return rationals;
}

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Answer 1

, Collections.sort(rationals) .

, Collections.sort List of Comparable. Comparable.compareTo(), , , compareTo , .

Answer 2

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Answer 3

In the main method of your application, you must create a list of Rationals and then use the Collections.sort () method.

You must create a random list of Rationals and then use Collection.sort(rationalsList);