Sonar : lambda - Remove useless curly braces around statement

Question

These code examples:

import java.util.Observer;

public class Main {
    public static void main(String[] args) {
        Observer observer = (o, arg) -> {
            if (arg != null) {
                System.out.println(arg);
            }
        };
    }
}

---

import java.util.Observer;

public class Main {
    public static void main(String[] args) {
        Observer observer = (o, arg) -> {
            try {
                String test = (String) arg;
                ...
            }
            catch (ClassCastException e) {
            }
        };
    }
}

are noncompliant with this sonarqube rule:

Lamdbas containing only one statement should not nest this statement in a block : Remove useless curly braces around statement

how can i fix it ?

Answer 1

The classification of these curly braces as “useless” is wrong.

You can omit curly braces around a single expression statement, that is, for example, a method invocation, a new expression, or x++, x+=y, etc.

Or you can transform a sole … -> { return x; } statement into an expression … -> x.

But you can’t omit curly braces around every single statement.

You can’t fix that. The only thing you can do is file a bug report.

By the way, even then, removing them is not necessarily a readability improvement. It depends…