Why must throw statements be enclosed with a full code block in a lambda body?

Question

If there is a single statement in a lambda function, we can omit defining the full code block for it:

new Thread(() -> System.out.println());

Answer 1

In Java8, the grammar of a lambda body only accepts an expression or a block. Whereas throwing an exception is a statement, not an expression.

throwStatement: 'throw' expression ';' ;

lambdaBody: expression | block;

expression: lambdaExpression | assignmentExpression;

block : '{' blockStatements? '}' ;

Maybe it can be enhanced by including throwStatement into lambdaBody in the next jdk version if it is needed. Indeed, we need that as you mentioned above. for example:

lambdaBody: expression | block | throwStatement;