Help! Field initialization sample in JLS

[Haining Mu]

hi all,here is the samle code from JLS 8.3.2.3 regarding field initialization, I already comment-off what author marked "error", but it still have problems of "forward reference". I also include error from javac. Can anybody explain? Does the author wrong, or Sun's compiler does not strict follow JLS?

class UseBeforeDeclaration {
static {
x = 100; // ok - assignment
//int y = x + 1; // error - read before declaration
int v = x = 3; // ok - x at left hand side of assignment
int z = UseBeforeDeclaration.x * 2;
// ok - not accessed via simple name
Object o = new Object(){
void foo(){x++;} // ok - occurs in a different class
{x++;} // ok - occurs in a different class
    };
        }
{
j = 200; // ok - assignment
//j = j + 1; // error - right hand side reads before declaration
int k = j = j + 1;
int n = j = 300; // ok - j at left hand side of assignment
//int h = j++; // error - read before declaration
int l = this.j * 3; // ok - not accessed via simple name
Object o = new Object(){
void foo(){j++;} // ok - occurs in a different class
{ j = j + 1;} // ok - occurs in a different class
};
}
int w = x= 3; // ok - x at left hand side of assignment
int p = x; // ok - instance initializers may access static fields
static int u = (new Object(){int bar(){return x;}}).bar();
// ok - occurs in a different class
static int x;
int m = j = 4; // ok - j at left hand side of assignment
int o = (new Object(){int bar(){return j;}}).bar();
// ok - occurs in a different class
int j;
}

errors:

D:\>javac UseBeforeDeclaration.java
UseBeforeDeclaration.java:3: illegal forward reference
                x = 100; // ok - assignment
                ^
UseBeforeDeclaration.java:5: illegal forward reference
                int v = x = 3; // ok - x at left hand side of assignment
                        ^
UseBeforeDeclaration.java:14: illegal forward reference
                j = 200; // ok - assignment
                ^
UseBeforeDeclaration.java:16: illegal forward reference
                int k = j = j + 1;
                        ^
UseBeforeDeclaration.java:16: illegal forward reference
                int k = j = j + 1;
                            ^
UseBeforeDeclaration.java:17: illegal forward reference
                int n = j = 300; // ok - j at left hand side of assignment
                        ^
UseBeforeDeclaration.java:31: illegal forward reference
        int m = j = 4; // ok - j at left hand side of assignment
                ^
7 errors

you can see the original here:
[url = http://java.sun.com/docs/books/jls/second_edition/html/classes.doc.html#287406
[/url]

[This message has been edited by Haining Mu (edited June 19, 2001).]
[This message has been edited by Haining Mu (edited June 19, 2001).]

[Manfred Leonhardt]

Hi Haining,
The author screwed up! Static blocks are executed at class load time in the order of top down. Since you are not declaring x before you are trying to assign it you will get errors. If you move the static int x; declaration above static block it will not complain about that.
I would think that you would have the same problem with the instance declarations.
Regards,
Manfred.

[Cindy Glass]

Let me get this straight.
Sun writes some sample code just to show you what NOT TO DO, and you are trying to get it to COMPILE? They NEVER said that the thing would ever work. They ONLY said "Don't do this".
Perhaps you would be better of just absorbing the intent of the example.