Question

We have X methods and we like call the one relative to user settings which of the following runs faster?

Case 1:

int userSetting = 1;
Method method = Class.getDeclaredMethod("Method" + userSetting);
method.invoke();

Case 2:

 int userSetting = 1;
 switch(userSettings) {
     case 0:
         Method0();
     break;
     case 1:
         Method1();
     break;
     ...
     ...
 }

Case 3:

int userSetting = 1;
if(userSetting == 0){
    Method0();
} else if(userSetting == 1){
    Method1();
} else....

Also:

• You think one even if slower is better practice that the others? If yes why?
• There is another way witch is better/faster…please tell us.

Thanks

Answer 1

Option 1 uses reflection, and thus will probably be slower, as the javadocs indicate:

Performance Overhead
    Because reflection involves types that are dynamically resolved, certain Java 
    virtual machine optimizations can not be performed. Consequently, reflective 
    operations have slower performance than their non-reflective counterparts, 
    and should be avoided in sections of code which are called frequently in 
    performance-sensitive applications.

However it is easier to maintain this option then options 2+3.

I would suggest you to use a complete different option: use the strategy design pattern. It is more likely to be faster and much more readable then the alternatives.