Why is the semicolon not required but allowed at the end of a class definition?

Question

I\'m trying to shift from C++ to Java.

What I wonder is, in C++, after a class definition, a semicolon (;) is required, but in Java it isn\'t.

T

Answer 1

In the early days, allowing this was one of the ways in which Java was made more familiar to C/C++ programmers. This familiarity was important to the adoption of Java.

Here's how it works syntactically.

After a top-level class, it works because a compilation unit contains this sequence, according to JLS 7.3:

CompilationUnit:
 PackageDeclaration(opt) ImportDeclarations(opt) TypeDeclarations(opt)

And a type declaration is any one of the following, according to JLS 7.6:

TypeDeclaration:
   ClassDeclaration
   InterfaceDeclaration
   ;

After a member class, nested in some other class, it works because a semicolon can be a class member declaration, according to JLS 8.1.6:

ClassMemberDeclaration:
    FieldDeclaration
    MethodDeclaration
    ClassDeclaration    
    InterfaceDeclaration
    ;

After a local class, inside a method, it works because a semicolon can be an empty statement, according to JLS 14.6:

EmptyStatement:
    ;