compile time constant

[ajay solanki]

Hi

Please tell me, what is complitime constant?
I read it from SCJP5.0 book written by kethy.

Is there any run time constant ?

Thanks

[balajee annamalai]

Please refer the below link,
https://coderanch.com/t/268764/java-programmer-SCJP/certification/Compile-time-constants

[Aditya Jha]

Hi,

Ranchers, please correct me if I'm wrong.

What I get from a compile-time constant is a 'final' identifier declared and assigned a literal value. Something like

final int i = 10;

Now, obviously this can be either one of the primitives or a String ('cause literals can only be written for them).

The reason such an identifier is called a compile-time constant is that compiler can safely assume the value of the same and for optimal performance, may 'replace' its value whereever it is used in code.

A run-time constant can be thought of as a 'final' identifier which is assigned a value that can be decided only at run-time.

Example,

final DateFormat DOB_DISPLAY_FORMAT = new SimpleDateFormat("dd-MMM-yyyy");

or

public class A {
  public final int SOME_PROP;
 
  public A() {
    SOME_PROP = 1;
  }
 
  public A(int i) {
    SOME_PROP = i;
  }
}

Hope this helps.

- Aditya Jha