CODEWITHSUNDEEP
javaandroid
Dima
Dima

Reputation: 71

Constructor is never used

Have some questions.

I have a parent class 

abstract class Tetramino{}

and some child classes that extends parent with a default constructors listed explicitly

class LineHorizontal extends Tetramino
{
  LineHorizontal() { // do some}
}

class LineVertical extends Tetramino
{
  LineVertical () {// do some}
}

And I have a generator class which generate child classes

class MinoGenerator
{
    private static final String TAG = "MinoGenerator";

    private static final Class[] types = {LineHorizontal.class,     LineVertical.class, Square.class,
        L0.class, L90.class, L180.class, L270.class, LR0.class, LR90.class, LR180.class,
        LR270.class, T0.class, T90.class, T180.class, T270.class, Z0.class,
        Z180.class, RZ0.class, RZ180.class};

    static Tetramino next()
    {
        try{
           int type = (int) (Math.random() * types.length);
           return (Tetramino) types[type].newInstance();
       } catch (Exception e){
          e.printStackTrace();
          Log.e(TAG, "Error while creating new tetramino");
      }
      return null;
    }
}

When I want create new one, I call next(). Then a newInstance() function, calls consturtors implicit and return a random one. But android studio mark a constuctors with warning "Constructor neve used", how I can fix it? Thanks for reply.

Upvotes: 2

Views: 6717

Answers (2)

Andy Turner
Andy Turner

Reputation: 140299

A better approach to this, assuming you're using Jack, is to use lambda expressions:

private static final List<Supplier<? extends Tetramino>> types =
    Collections.unmodifiableList(
        Arrays.asList(
            LineHorizontal::new,  // or () -> new LineHorizontal()
            LineVertical::new,
            // etc, for other types
            ));

Then, in your next() method:

return types[type].get();

Note that this is actually using the constructor of the class, so you won't have unused warnings any more. And it's more type safe than reflection.

Upvotes: 0

David Geirola
David Geirola

Reputation: 632

Try adding @SuppressWarnings("unused") hover your class

Like:

@SuppressWarnings("unused")
class MyClass{

    public MyClass(){}
}

This works on IntelliJ IDEA and i think that can work also on Android Studio

Upvotes: 2

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