reflection: noSuchMethodException

[Matthijs Blaas]

I try to invoke a method (setIgnoreRepaint) only if it's available on the
used JVM through reflection. Problem is that it throws me a
java.lang.NoSuchMethodException:
java.awt.Component.setIgnoreRepaint(java.lang.Boolean) exception even on
JVM's where it is available... I cant figure out what im doing wrong.

An example can be found at: http://www.virtual-boy.org/applet/refl.html (you
can see the error at the java console)

Sources:
http://www.virtual-boy.org/applet/refl.java

 

[Andrew Thompson]

I try to invoke a method (setIgnoreRepaint) only if it's available on the
used JVM through reflection. Problem is that it throws me a
java.lang.NoSuchMethodException:
java.awt.Component.setIgnoreRepaint(java.lang.Boolean) exception even on
JVM's where it is available... I cant figure out what im doing wrong.

You are using Boolean, rather than boolean.

<sscce>
import java.applet.*;
import java.lang.reflect.Method;

public class Refl extends Applet {

public void start() {
try {
Class ob = Class.forName("java.awt.Component");
Method method = ob.getMethod("getComponentAt",
new Class[]{Class.forName("java.awt.Point")} );

ob = Class.forName("java.awt.Component");
method = ob.getMethod("setIgnoreRepaint",
new Class[]{Class.forName("java.lang.Boolean")} );
}
catch(Exception e) {
e.printStackTrace();
}
}
}
</sscce>

As to how you represent a boolean in such cases, that is
left as an exercise for the OP. (No, I have no idea.)

 

[Murray]

As to how you represent a boolean in such cases, that is
left as an exercise for the OP. (No, I have no idea.)

Class booleanPrimitive = Boolean.TYPE;

 

[Andrew Thompson]

Class booleanPrimitive = Boolean.TYPE;

Yep, that's it. That works here just fine.

 

[Matthijs Blaas]

As to how you represent a boolean in such cases, that is

Yep, that's it. That works here just fine.

Great, I have it working now! I'd never guessed I had to use the TYPE
field... is that static class used by the Boolean class itself for actual
initialisation of an boolean object?

 

[Oscar kind]

I'd never guessed I had to use the TYPE
field... is that static class used by the Boolean class itself for actual
initialisation of an boolean object?

Almost. The TYPE field denotes a special Class instance describing a
primitive type. AFAIK it is not used for initialization, as primitive
types are not subclasses of Object.