Question

What's wrong with this code? #Java

Why I am getting error in : int BusCompare = o1.numberOfBusinesses.compareTo(o2.numberOfBusinesses);

public class TypeComparator implements Comparator<Type> {
    @Override
    public int compare(Type o1, Type o2) {
//        return o1.name.compareTo(o2.name);
        int NameCompare = o1.name.compareTo(o2.name);
        int BusCompare = o1.numberOfBusinesses.compareTo(o2.numberOfBusinesses);

        // 2-level comparison using if-else block
        if (NameCompare == 0) {
            return ((BusCompare == 0) ? NameCompare : BusCompare);
        } else {
            return NameCompare;
        }
    }
}

public class Type implements Comparable<Type> {
    int id;
    String name;
    int numberOfBusinesses;

    public Type(int id, String name, int numberOfBusinesses) {
        this.id = id;
        this.name = name;
        this.numberOfBusinesses = numberOfBusinesses;
    }

    @Override
    public String toString() {
        // Prints the information for each Chain object
        // you can use it for testing your solution
        return "[Chain with id = " + this.id + ", name = " + this.name +
                ",  n businesses " + this.numberOfBusinesses + "]";
    }

    @Override
    public int compareTo(Type o) {
        return id - o.id;
    }
    
}

public class Main {

    public static void main(String[] args) {
   // write your code here
        Type c1 = new Type(10, "Target", 1844);
        Type c2 = new Type(2, "Whole Foods", 480);
        Type c3 = new Type(3, "Whole Foods", 500);
        List<Type> arr = new ArrayList<>();
        arr.add(c1);
        arr.add(c2);
        arr.add(c3);
        Collections.sort(arr, new TypeComparator());
//        System.out.println(c2.equals(c3));
        System.out.println(arr);
    }
}

Answer 1

You can change the line to the :

int BusCompare = String.valueOf(o1.numberOfBusinesses).compareTo(String.valueOf(o2.numberOfBusinesses));

Now the error can be completely gone

Modified Code :

import java.util.*;

class TypeComparator implements Comparator<Type> {
@Override
public int compare(Type o1, Type o2) {
// return o1.name.compareTo(o2.name);
int NameCompare = o1.name.compareTo(o2.name);
int BusCompare = String.valueOf(o1.numberOfBusinesses).compareTo(String.valueOf(o2.numberOfBusinesses)); // changed line

// 2-level comparison using if-else block
if (NameCompare == 0) {
return ((BusCompare == 0) ? NameCompare : BusCompare);
} else {
return NameCompare;
}
}
}
class Type implements Comparable<Type> {
int id;
String name;
int numberOfBusinesses;

public Type(int id, String name, int numberOfBusinesses) {
this.id = id;
this.name = name;
this.numberOfBusinesses = numberOfBusinesses;
}

@Override
public String toString() {
// Prints the information for each Chain object
// you can use it for testing your solution
return "[Chain with id = " + this.id + ", name = " + this.name +
", n businesses " + this.numberOfBusinesses + "]";
}

@Override
public int compareTo(Type o) {
return id - o.id;
}
  
}
public class Main {

public static void main(String[] args) {
// write your code here
Type c1 = new Type(10, "Target", 1844);
Type c2 = new Type(2, "Whole Foods", 480);
Type c3 = new Type(3, "Whole Foods", 500);
List<Type> arr = new ArrayList<>();
arr.add(c1);
arr.add(c2);
arr.add(c3);
Collections.sort(arr, new TypeComparator());
// System.out.println(c2.equals(c3));
System.out.println(arr);
}
}

OUTPUT :