Fun with constants in Java
The following code does not compile:
public class A {
public static void main(String[] args) {
int i = Integer.parseInt(args[0]);
switch (i) {
case X: System.out.println("ONE!"); break;
case Y: System.out.println("TWO!"); break;
default: System.out.println("ZERO!"); break;
}
}
public static final int X = B.getNumber("X");
public static final int Y = B.getNumber("Y");
}
class B {
public static int getNumber(String s) {
if (s.equals("X")) {
return 1;
}
else if (s.equals("Y")) {
return 2;
}
else {
return 0;
}
}
}
The compile error is:
A.java:5: constant expression required
case X: System.out.println("ONE!"); break;
^
A.java:6: constant expression required
case Y: System.out.println("TWO!"); break;
^
2 errors
I think I'll leave explaining why as an exercise for the reader. (Or for a future post. ;-)
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