Java 8: Lazy init field with lambdas

Originally published on 2018-04-27

The cost of postponed lazy field init in Java is checking if field is null every time we need to get the value

Note: T implements Singleton pattern.

class Clazz{
    //static instance holder
    private static Clazz instance;
    // private constructor
    private Clazz{
    // some expensive instantiation
    }
    // getter
    public static Clazz getInstance() {
        if(instance == null){
            instance == new Instance();
        }
        return instance;
    }
}

Is it possible while utilising Java 8 lambdas to improve performance? Apparently, there is Supplier interface for that!

class Clazz{
    private Supplier fooField = () -> {
       Clazz val = expensiveInit();
       fooField = () -> val;
       return val;
    };

    public Clazz getFoo(){
       return fooField.get();
    }
}

PS. This is not thread safe.