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Saturday, 14 September 2013

Java Best Practice - Declarations


Number Per Line
int level; // indentation level

int size; // size of table
is prepared over
int level, size;
Do not put different type on the same line. Example:
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:
int          level;             // indentation level

int size; // size of table

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.
void methodName() {

int var1 = 0; //beginning of method block

if (condition) {

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

….

}

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

….

myMethod() {

if (condition) {

int count; //AVOID

}

}
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 “{”
class Example extends Object {

int var1;

int var2;

Example(int i, int j){

var1 = i;

var2 = j;

}



int emptyMethod() {}

….

}
5.Method are separated by a blank line
Annamalai Thangaraj

Annamalai is working as Technical Lead in Leading Telecom company with 5+ years experience in Identity and Access Management , Telecom and Networks, BigData, Java, Spring, Struts, Hibernate, AngularJS, and Enterprise Web Application Development.

Website: Java Tutorials Corner

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Item Reviewed: Java Best Practice - Declarations Rating: 5 Reviewed By: Annamalai Thangaraj