Modifier Keyword order in Java

问题:

Every time I write method in Java with more keywords than public void, every time I write it another way. Sometimes "static public void" sometimes "public static void" etc.

What is the best order (best practices) for these keywords?

[abstract/static] [final] [synchronized] [public/private/protected] [result_type] ???

回答1:

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. Here is the preferred order:

[ public | protected | private ]

static

abstract

synchronized

[ transient | volatile ]

final

native

strictfp

[ int | long | String | class | enum | interface etc. ]

回答2:

Checkstyle (which implements the suggestions of the Java Language Specifications sections, 8.1.1, 8.3.1, and 8.4.3) says:

1. public
2. protected
3. private
4. abstract
5. default
6. static
7. final
8. transient
9. volatile
10. synchronized
11. native
12. strictfp

回答3:

The "best" would be to follow the Java Coding Style Guide, that states in 6.2 (method declaration):

public static final synchronized long methodName()
    throws ArithmeticException, InterruptedException {
    static int count;
}

回答4:

The best order is the one that the rest of your code uses.

回答5:

The custom usage order of the modifiers is mentioned in the Java Language Specification (so no need to have an own opinion ;-)) e.g. for method modifiers you will find the following definition (extract):

MethodModifiers:
    MethodModifier
    MethodModifiers MethodModifier

MethodModifier: one of
    Annotation public protected private abstract
    static final synchronized native strictfp

If two or more (distinct) method modifiers appear in a method declaration, it is customary, though not required, that they appear in the order consistent with that shown above in the production for MethodModifier.

You will find this sentence at several other places where the usage of modifiers is specified, e.g. here for field modifiers.

(This is mostly copied from another answer of mine here).

回答6:

Like this:

public static final synchronized void calculate()

回答7:

This is my personal choice

public static final void method() { }
public void method() { }
public abstract void method() { }

this seems in line too with the java documentation

回答8:

Yes, there is a standard ordering.

If you use an IDE, you can set it up to format your code for you, i.e. in Eclipse in Preferences -> Java -> Editor -> Save Actions you can check the box "Format source code"

Then you don't have to worry about it any more. It will be done automatically whenever the file is saved and if your whole project uses this, then for the whole project has code that is formatted in the same way.