JuniorTheoryCommon

What happens when this program is compiled and run?

JAVA

import java.util.List;

public class Main {
    public static void main(String[] args) {
        List<Integer> xs = List.of(1, 2, 3);
        int total = 0;
        xs.forEach(x -> total += x);
        System.out.println(total);
    }
}

It does not compile

Expecting 6: a lambda is not a loop body; it may read local variables of the method but not assign to them, so total += x does not compile.
Expecting an error only when forEach runs: the effectively final rule is checked by the compiler, so the program never starts.

How can you sum the list without changing a local variable from a lambda?
Why does Java require a local variable used in a lambda to be effectively final?

Back to questions Open topic in roadmap →Answer it yourself — Quiz

Back to questions

JuniorTheoryCommon

What happens when this program is compiled and run?

JAVA

import java.util.List;

public class Main {
    public static void main(String[] args) {
        List<Integer> xs = List.of(1, 2, 3);
        int total = 0;
        xs.forEach(x -> total += x);
        System.out.println(total);
    }
}

It does not compile

Expecting 6: a lambda is not a loop body; it may read local variables of the method but not assign to them, so total += x does not compile.
Expecting an error only when forEach runs: the effectively final rule is checked by the compiler, so the program never starts.

How can you sum the list without changing a local variable from a lambda?
Why does Java require a local variable used in a lambda to be effectively final?

Back to questions Open topic in roadmap →Answer it yourself — Quiz