How to use declarations in java

This tutorial helps you to using declaration while java coding, this is one of the best part of java coding standard, the things will show you what you have to take care while declaring the variables in java code.

Number per line

One declaration per line is recommended since it encourages commenting. In other words,


int level; // indentation level
int size; // size of table

is always preferred over


int level, size;

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


int foo,  fooarray[]; //this is wrong!

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


int level; // indentation level
int size; // size of table
Object currentEntry; // currently selected table entry

Initialization

Try to initialize local variables where they’re declared. The only reason not to initialize a variable where it’s declared is if the initial value depends on some computation occurring first.

Placement

Put declarations only at the beginning of blocks. (A block is any code surrounded 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 myMethod() {
int int1 = 0; // beginning of method block

if (condition) {
int int2 = 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 hide declarations at higher levels. For example, do not declare the same variable name in an inner block:


int count;
...
myMethod() {
if (condition) {
int count = 0; // AVOID!
...
}
...
}

Class and Interface Declarations

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

• No space between a method name and the parenthesis “(” starting its parameter list

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

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


class Sample extends Object {
int ivar1;
int ivar2;

Sample(int i, int j) {
ivar1 = i;
ivar2 = j;
}

int emptyMethod() {}

...
}

Methods are separated by a blank line