■† You cannot have more than one public class per file.
■† The only five allowable class keywords are:† public, abstract, final, extends, and implements.
■† Classes cannot be protected, private, native, synchronized, or final and abstract together. (But inner classes can be private.)
■† A class must be made abstract if it contains just one or more abstract methods.
■† Classes can be made abstract any time you wish Ė even when not necessary due to Java rules.
■† Classes that are abstract can contain non-abstract methods.
■† A class statement, along with an interface and a constructor, are the only three Java statements that can appear with absolutely no modifiers.
Methods canít do so, as they need a return type or void.†
Variables can't, as they need a type.
■† Note that you don't need a class statement to get a good compile.† The JVM will compile a completely empty source file without error.