Why can't you create a 1 statement function without curly braces?

Question

So, in most programming language, if you are using a loop or an if, you can do it without curly braces if there is only a single statement in it, example:

if (true)
    //Single statement;

for (int i = 0; i < 10; i++)
    //Single Statement

while (true)
    //Single statement

However, it doesn't work for functions, example:

void myFunction()
    //Single Statement

So, my question, why doesn't it work for functions?

Answer 1

C++ needs it to disambiguate some constructs:

void Foo::bar() const int i = 5;

Now does the const belong to bar or i ?

Answer 2

Because language grammar forbids you to do that.

The Java grammar defines a method as following:

MethodDeclaration:
    MethodHeader MethodBody

Methodbody as:

MethodBody:
    Block 
    ;

Which means either a Block (see below) or a single semicolon

Block:
    { BlockStatementsopt }

And a block as one or more statements within curly brackets.

However an if is defined as:

IfThenStatement:
    if ( Expression ) Statement

Where no block is needed after the closing ) and therefore a single line is ok.

Why they chose to define it that way? One can only guess.

Grammar can be found here: http://docs.oracle.com/javase/specs/jls/se7/html/index.html