Best Practice in defining variables

Question

Hi All
What is the best practice to use variables inside a method and any specific advantage .i.e. initializing variables starting of the method vs defining them where they are required.
public String abc(){
int i = 0;
String s = null;
i = 10 + 50;
s = "Java" + "world";
return s;
vs
public String abc(){
int i = 10 + 50;
String s = "Java" + "world";
return s;
}

Answer 1

SRAVZ wrote:
What is the best practice to use variables inside a method and any specific advantage .i.e. initializing variables starting of the method vs defining them where they are required.As the others wrote the later is preferred. One reason is that this can save memory.
Another (IMHO) important reason is that it eases the use of refactorings provided by your IDE.
Look at this code: public int testRefactoring() {
          int result = 0, factor = 0;
          RefactoringTest rt = new RefactoringTest();     
          result = rt.getA();
          factor *=result ;
          result= factor;
          result += rt.getB();
          return result;
     }As you may see the calculation of the result uses only values from the class <tt>RefactoringTest</tt> so it should be placed there. This is no problem since almost any IDE can do this in 2 steps:<ol><li>extract method</li><li>move method (to one of its parameters)</li></ol>Lets start with the first step: <ul><li>select lines 4 to 7 </li><li> hit "shift+alt+m" (in eclipse),</li><li> enter a name for the new method </li><li> click OK.</li></ul>
The result is a method with 3 Parameters. Two of them are useless.
If you'd switch line 2 and 3 you could include the variable declaration in your selection thus leading to a method with one parameter only...
bye
TPD