Clean up "Convert if/else if/else chain with 3 blocks min to switch" in 2024-09 changes code semantic by not considering null

[FlorianKroiss]

Consider the following example:

public class Dummy {

    enum TestEnum {
        A, B, C
    }

    public int doSomething(final TestEnum val) {
        if (val == TestEnum.A) {
            return 1;
        }
        else if (val == TestEnum.B) {
            return 2;
        }
        else if (val == TestEnum.C) {
            return 3;
        }
        return 4;
    }

}

Calling this method with null returns 4.

Applying the code clean up "Convert if/else if/else chain with 3 blocks min to switch" produces the following code

public class Dummy {

    enum TestEnum {
        A, B, C
    }

    public int doSomething(final TestEnum val) {
        switch ( val ) {
            case TestEnum.A:
                return 1;
            case TestEnum.B:
                return 2;
            case TestEnum.C:
                return 3;
            default:
                break;
        }
        return 4;
    }

}

The cleaned up code now throws a NullPointerException, when being called with null, instead of falling through to return 4;.
I guess in case null was not explicitly treated in the original code, then the correct clean up would be to use case null, default: instead of default:.

[jjohnstn]

BTW: thanks @FlorianKroiss for reporting this. The cleanup has been changed to add the case null when the Java version allows it and to create an if statement otherwise.