Compile time constant

[Vishnu Prakash]

 
class FinalVarTest {

final int j = 55;     // 1
byte h = j;   // 2
 
public static void main(String[] args) {
FinalVarTest nc = new FinalVarTest();
byte b1 = nc.j;  // 3
}
}

why am I getting error in main method when I try to assign a compile time constant to a byte variable(3). I am doing the same at (2) for byte b where I am not getting any error.

[Barry Gaunt]

I'll take a stab at this (meaning I could be wrong).
If you look at the JLS, at the definition for a compile time constant, you will find:

# Simple names that refer to final variables whose initializers are constant expressions
# Qualified names of the form TypeName . Identifier that refer to final variables whose initializers are constant expressions

nc.j is not one of these types of names. j is a simple name, and if j was static, FinalVarTest.j would be a correct qualified name.

nc.j is accessing j through a reference to an object. It's a qualified name, but not of the form required by JLS.
[ June 17, 2005: Message edited by: Barry Gaunt ]

[Barry Gaunt]

Here I made j static as well as final:

class FinalVarTest {

final static int j = 55;     // 1
byte h = j;   // 2
 
public static void main(String[] args) {
FinalVarTest nc = new FinalVarTest();
byte b1 = FinalVarTest.j;  // 3
}
}  

That compiles.

[Barry Gaunt]

Here I've used j (simple name) and this.j (a qualified name - but not of the type required by JLS)

class FinalVarTest {

final int j = 55;     // 1
byte h = j;   // 2

public void m() {
    byte b1 = j;
    // byte b2 = this.j;  // this does not compile!
}
}

[Vishnu Prakash]

That was the doubt I had for a long time. Thanks for the wonderful explanation.