CODEWITHSUNDEEP
javalambdarefactoringoption-type
Developus
Developus

Reputation: 1462

How to refactor Optional.isPresent() + Optional.get () to Optional.ifPresent()?

I have a code:

public interface A{
    default Optional<MyClass> getMyClass() { 
        return Optional.empty(); 
    }

    default boolean isPresent(){ 
        return getMyClass().isPresent();
    }
}

public enum MyEnum implements A{
    private MyClass someObject;

    MyEnum(MyClass someObject) {
        this.someObject = someObject;
    }

    //...
    @Override
    public Optional<MyClass> getMyClass() {
        return Optional.ofNullable(someObject);
    }
}

I would like to change this code into something like Optional.ifPresent(). I need this instead of Optional.isPresent + Optional.get which I have now.

I tried to do something like Optional.ofNullable(someObject).ifPresent() but I have no idea what should be placed in ifPresent() parameter to get same result as from above code.

EDIT:

From comments I understood that a solution is to change if(something.isPresent()){ //do something } to something.getMyClass().ifPresent(val -> //do something); in class where I use interface.

Upvotes: 1

Views: 1264

Answers (1)

Dmitry Gorkovets
Dmitry Gorkovets

Reputation: 2286

allocer,

Case 1

if(something.isPresent())
{ 
    //do something 
}

In this block you can work with not final variables, for example:

String myString = null;
if(something.isPresent())
{ 
    myString = "Hello";
}

Case 2

something.getMyClass().ifPresent(val -> //do something);

In this block you cannot work with not final variables, for example:

String myString = null;
something.getMyClass().ifPresent(val -> myString = "Hello"); // does not work

to fix it you need to use one element list:

final String myString[] = {""};
something.getMyClass().ifPresent(val -> myString[0] = "Hello"); // will work

If you have final object then you can invoke its methods to modify it:

final SomeClass object = new SomeClass();
something.getMyClass().ifPresent(val -> object.someMethod()); // will work

Also you can use method references:

class SomeClass {

    // ... 

    public void calculate(MyClass value) {
        // do something
    }

    public void someMethod() {
        something.getMyClass().ifPresent(this::calculate);
    }
}

Upvotes: 1

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