keyword : Java Glossary

Reserved Keywords

Java reserves some words. They cannot be used as variable, method or class names.

The bold ones I consider more important since they demark major blocks of code. assert arrived with JDK (Java Development Kit) 1.4. enum arrived with JDK 1.5. const and goto are not currently used. They may be there just in case C++ programmers use them by mistake to enable the compiler to give a more meaningful error message.

What keywords Can Be Applied to What

Notes

² — static blocks may not occur inside methods.

³ — final methods cannot be overridden in a subclass. This is not the same as C++ const.

⁴ — you can’t derive from a final class.

⁵ — implemented in some other language, usually C, C++ or assembler.

⁶ — May be asynchronously modified by other threads. Volatile is not a substitute for task synchronization.

⁷ — Interfaces and all their methods are public abstract by default. It is considered poor form to explicitly code the public abstract.

Table composed by Razvan.

Keyword Order

In theory it does not matter if you say public static final or final static public, but if you follow the usual convention, other people will able to read your code more easily. The Java language specification makes recommendations about the order of modifiers. It strongly encourages the following order:

• for fields: public, protected, private, static, final, transient, volatile [int | long | String… ].
• for methods: public, protected, private, abstract, static, final, synchronized, native, strictfp [ void | int | long | String… ].
• for classes: public, protected, private, abstract, static, final, strictfp, class.
• for interfaces [public], [abstract], strictfp, interface.

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