Issues with setter methods involving final field

Question

In my class three instance variables which are all final. However, when I try to do something like this.inputsRelated = inputsRelated in the setter method, I get an understandable error which says final field cannot be assigned. But what would the approach in setter methods/how should I handle the methods public void setInputsRelated(boolean inputsRelated) and public void setExpected(int expected) ? Thanks in advance!

public class ExceptionLogicParameters extends RuntimeException {

    public final boolean inputsRelated;
    public final int expected;
    public final int found;

    public ExceptionLogicParameters(boolean inputsRelated, int expected, int found)
    {
        this.inputsRelated = inputsRelated;
        this.expected = expected;
        this.found = found;
    }

    @Override
    public String toString()
    {
        return "Get the the hell out of here!";
    }

    public boolean getInputsRelated()
    {
        return this.inputsRelated;
    }

    public int getExpected()
    {
        return this.expected;
    }

    public int getFound()
    {
        return this.found;
    }

    public void setInputsRelated(boolean inputsRelated)
    {
        this.inputsRelated = inputsRelated;
    }

    public void setExpected(int expected)
    {
        this.expected = expected;
    }

}

Those methods shouldn't exist if the fields are final. final fields have to be set in the declaration or the constructor. — axblount, Apr 02 '15 at 17:32
If you want to reassign the value on those fields, why using final? — Aninda Bhattacharyya, Apr 02 '15 at 17:33
Resolved! The professor made a mistake making instance variables final. — Shohin, Apr 02 '15 at 17:49
See also [calling setters from a constructor](https://stackoverflow.com/questions/4893558/calling-setters-from-a-constructor) — Vadzim, Feb 05 '20 at 10:07

Anderson Vieira · Accepted Answer · 2015-04-02T17:38:00.123

3

If the fields are final they can only be initialized in the variable declaration or in the constructor. Setter methods make no sense for final fields.

You should analyse your code and decide if the fields should indeed be final and, if that is the case, discard the setter methods. If you really need to create the setters, you must remove the final modifier.

edited Apr 02 '15 at 17:38

answered Apr 02 '15 at 17:33

Anderson Vieira

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Thanks for the quick reply, but my instructions are laid out like that that I should include setters methods. – Shohin Apr 02 '15 at 17:34
You can't do both at the same time. If you really need to create the setters, you should remove the `final` modifier. – Anderson Vieira Apr 02 '15 at 17:36
Resolved! The professor made a mistake making instance variables final. – Shohin Apr 02 '15 at 17:49

score 0 · Answer 2 · answered Apr 02 '15 at 17:33

0

You should not have setters for final instance variables because you cannot set them. Either make your variables non-final or remove the setters.

answered Apr 02 '15 at 17:33

Samuel

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score 0 · Answer 3 · answered Apr 02 '15 at 17:35

0

you can only getter methods, there is no use of setter method if final. If want to provide setter there no use of making them final.

answered Apr 02 '15 at 17:35

Saif

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score 0 · Answer 4 · answered Apr 02 '15 at 17:42

Once you make a variable or reference final you are not allowed to change that and compiler will verify this and raise compilation error if you try to re-initialized final variables in java.

In your case the mutator and accessor (set/get) methods are useless due to the prior final declaration of your variable.

Issues with setter methods involving final field

4 Answers4