How to resolve Variable in lambda expression should be final or effectively final in forEach Java 8

Published: 30 November 2022
on channel: smashplus

920

I want to limit the number of values in an ArrayList in the below code

newExam.getQuestionList().stream().forEach(qtn- >{
String title=qtn.getOption1();
if(qtn.getCorrectOptionIndex()==2){
title=qtn.getOption2();
}else if(qtn.getCorrectOptionIndex()==3){
title=qtn.getOption3();
}

dragDropEntities.add(new DragDropEntity(qtn.getId().getQtnId(), title, qtn.getImage()));

I decided to use this way,

int i = 0;
list.stream.forEach(item -> {
i++;
});
but this gives me the error "Variable used in lambda expression should be final or effectively final"

Because this variable I is incrementing inside lambda expression it is not final so this gives the above error.

So I fixed this by using the AtomicInteger in the below way,

AtomicInteger atomicInteger=new AtomicInteger();
newExam.getQuestionList().stream().forEach(qtn->{
String title=qtn.getOption1();
if(qtn.getCorrectOptionIndex()==2){
title=qtn.getOption2();
}else if(qtn.getCorrectOptionIndex()==3){
title=qtn.getOption3();
}
if(atomicInteger.getAndIncrement()<6) {
dragDropEntities.add(new DragDropEntity(qtn.getId().getQtnId(), title, qtn.getImage()));
}

}
);
This solves the issue and I can see the list correctly with six elements

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