Java Best Practice - Declarations

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Number Per Line

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1.int level; // indentation level

2. 

3.int size; // size  of table

is prepared over

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1.int level, size;

Do not put different type on the same line. Example:

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1.int foo, fooarray[]; //WRONG

Note: The example above use one space between the type and the identifier. Another acceptable alternative is to use tabs, example:

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1.int          level;             // indentation level

2. 

3.int          size;             // size of table

4. 

5.Object    currentEntry; // currently selected table entry

Initialization
Try to initialize local variable where they are declared. The only reason to initialize a variable where it’s declared is if the initial value depends on some computation occurring first.

Placement
Put declaration only at beginning of blocks.(A block is any code surround by curly braces “{” and “}” ) Don’t wait to declare variables until their first use, it can confuse the unwary programmer and hamper code portability within the scope.

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01.void methodName() {

02. 

03.      int var1 = 0;                //beginning of method block

04. 

05.      if (condition) {

06. 

07.         int var2 = 0;            //beginning of “if” block

08. 

09.         ….

10. 

11.      }

12. 

13.}

The one exception to the rule is indexes of for loops, which in Java can be declared in the for statement:

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1.for(int i = 0; i < maxLoops; i++) { … }

Avoid local declarations that hides declarations at higher levels. For example, do not declare the same variable name  at inner block.

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01.int count;

02. 

03.….

04. 

05.myMethod() {

06. 

07.       if (condition) {

08. 

09.           int count;        //AVOID

10. 

11.       }

12. 

13.}

Class and Interface Declaration
When coding Java classes and interfaces, the following formatting rules should be followed:

1. No space between method name and parenthesis “(” starting its parameter list


2. Open brace “{” appears at the end of same line as the declaration statement


3. Closing brace “}”  starts a line by itself indented to match its corresponding opening statement, except when it is null statement the “}” should appear immediately after the “{”

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01.class Example extends Object {

02. 

03.       int var1;

04. 

05.       int var2;

06. 

07.       Example(int i, int j){

08. 

09.                    var1 = i;

10. 

11.                    var2 = j;

12. 

13.       }

14. 

15. 

16. 

17.       int emptyMethod() {}

18. 

19.       ….

20. 

21.}

5.Method are separated by a blank line

Java Java Best Practice 9/14/2013 07:10:00 pm