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javaexceptioncomparable

What type of Exception should I throw if the wrong type of object is passed?

What type of Exception should I throw if the wrong type of object is passed into my compareTo method?

ClassCastException?

Solution

  • It would be IllegalArgumentException in a general sense when the passed in value is not the right one.

    However, as @Tom's answer below suggests, it could also be a ClassCastException for incorrect types. However, I am yet to encounter user code that does this.

    But more fundamentally, if you're using the compareTo with generics, it will be a compile time error.

    Consider this:

    public class Person implements Comparable<Person> {
    private String name;
    private int age;

    @Override
    public int compareTo(Person o) {
       return this.name.compareTo(o.name);
    }
}

    Where do you see the possibility of a wrong type being passed in the above example?