CODEWITHSUNDEEP
java-8
amu61
amu61

Reputation: 351

Java 8 Lambda Expression

I am new learner for Java 8 lambda . I found a statement in a book (Java 8 for Really Impatient ), saying , "It is illegal for a lambda expression to return a value in some branches but not in others. For example, (int x) -> { if (x >= 0) return 1; } is invalid."

Can anyone explain this ? Please provide some examples.

Thanks in advance.

Upvotes: 0

Views: 517

Answers (2)

enders_uu
enders_uu

Reputation: 55

you have to ensure no matter "if" statement is true or false, there is always a return value or there is always not.

In your case:

illegal: (int x) -> { if (x >= 0) return 1; }
legal: (int x) -> { if (x >= 0) return 1; else return 0;}

This is because this method below is illegal

int lambda (int x){
    if (x >= 0)
        return 1;
}

Upvotes: 0

Eugene
Eugene

Reputation: 120998

I don't get it where you don't get it. Will this compile for example?

 static int test(int x) {
    if(x >= 0) {
        return 1;
    }
 }

Same goes for the lambda expression.

Upvotes: 4

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