Is it possible to specify a method as a method parameter?
e.g.
public void someMethod(String blah, int number, method MethodName)
Where MethodName is the name of a different method that needs to be specified.
Thanks
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not yet; we'll have to wait for java 8 for that featureirreputable– irreputable2011-10-22 03:31:23 +00:00Commented Oct 22, 2011 at 3:31
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4 Answers
No, but you specify an interface with a single method. And you can pass an anonymous implementation to the method
interface CompareOp {
int compare(Object o1, Object o2);
}
// Inside some class, call it Klass
public static int compare ( CompareOp comparator, Object o1, Object o2) {
return comparator.compare(o1, o2);
}
Then you would call it like
Klass.compare( new CompareOp(){
public int compare(Object o1, Object o2) {
return o1.hashCode() - o2.hashCode();
}
}, obj1, obj2 );
3 Comments
Blackvein
Sorry I'm still pretty new to Java. Could you elaborate on that for me?
Ruan Mendes
@QuanChi: Elaborate on what part?
Dave Newton
@QuanChi Please see the duplicate question in the question comments.
Using reflection, it is possible to pass Method as parameter. you can get more info from the java tutorial. It is not exactly like you did. I suggest you consider the options in the question that linked as possible duplicate before starting to use reflecion.
1 Comment
Ruan Mendes
Yes you could do this, at the expense of some nasty code and loss of type safety
If you want someMethod to call MethodName, then you should use a callback interface :
public interface Callback {
void callMeBack();
}
// ...
someObject.someMethod("blah", 2, new Callback() {
@Override
public void callMeBack() {
System.out.println("someMethod has called me back. I'll call methodName");
methodName();
}
});
Comments
With reflection even the following code is possible:
import java.lang.reflect.Method;
public class Test {
public static void main(final String a[]) {
execute("parameter to firstMethod", "firstMethod");
execute("parameter to secondMethod", "secondMethod");
}
private static void execute(final String parameter, final String methodName) {
try {
final Method method = Test.class.getMethod(methodName, String.class);
method.invoke(Test.class, parameter);
} catch (final Exception e) {
e.printStackTrace();
}
}
public static void firstMethod(final String parameter) {
System.out.println("first Method " + parameter);
}
public static void secondMethod(final String parameter) {
System.out.println("first Method " + parameter);
}
}
