Re: Class.getMethod in class's static initializer block
On Aug 1, 8:27 pm, Daniel Pitts <googlegrou...@coloraura.com> wrote:
chucky wrote:
If I call A.class.getMethod() from static initializer block of class
A, I get NoSuchMethodException.
Example:
class A {
static Method m;
private static void method(String str) {
System.out.println(str);
}
static {
try {
m = A.class.getMethod("method", new Class[] {String.class});
} catch(NoSuchMethodException e) {
throw new ExceptionInInitializerError(e);
}
}
}
This code always throws the ExceptionInInitializerError caused by
NoSuchMethodException.
Why does this happen?
Actually, I would like to write something like this:
class A {
private static void method(String str) {
System.out.println(str);
}
static Method m = A.method;
}
Of course, this code is invalid, but my idea is that the presence of
method is known at compile time, so I don't want the overhead of
reflection and I'd rather get a compilation error if there is no such
method. Something similar is possible with function pointers in C, but
is there sth. like that in Java?
Thanks for any help!
Using reflection should be a last resort, and reserved for frameworks.
Have you considered creating a functor class? Something like the
following:
interface StringCall {
void call(String s);
}
class A {
private static void method(String b) {
System.out.println(b);
}
static StringCall call = new StringCall() { public call(String s)
{ method(s); } };
}
Perhaps if you explained your goal, rather than the approach you are
trying, we could offer you better advice.
Thanks for your reply. I think I could do what I want with functors.
Here is what I want to do.
I have a code like this:
String str;
// some code
if(str.equals("string1")){ method1() }
else if(str.equals("string2")){ method2() }
else if(str.equals("string3")){ method3() }
....
// maybe 10-20 possibilities
....
else { /* default code */ }
And because I don't like it, I wanted to put each methodN() into a
static Map<String, Method> in static initializer.
Then I would change the above code into:
String str;
// some code
Method m = map.get(str);
if(m != null)
m.invoke();
else{ /* default code */ }
Some suggestions on this?
Many thanks in advance.