Java seek a method with specific annotation and its annotation element

Question

Suppose I have this annotation class

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.METHOD)
public @interface MethodXY {
    public int x();
    pu         


        

Answer 1

Here is a method, which returns methods with specific annotations:

public static List getMethodsAnnotatedWith(final Class type, final Class annotation) {
    final List methods = new ArrayList();
    Class klass = type;
    while (klass != Object.class) { // need to iterated thought hierarchy in order to retrieve methods from above the current instance
        // iterate though the list of methods declared in the class represented by klass variable, and add those annotated with the specified annotation
        for (final Method method : klass.getDeclaredMethods()) {
            if (method.isAnnotationPresent(annotation)) {
                Annotation annotInstance = method.getAnnotation(annotation);
                // TODO process annotInstance
                methods.add(method);
            }
        }
        // move to the upper class in the hierarchy in search for more methods
        klass = klass.getSuperclass();
    }
    return methods;
}

It can be easily modified to your specific needs. Pls note that the provided method traverses class hierarchy in order to find methods with required annotations.

Here is a method for your specific needs:

public static List getMethodsAnnotatedWithMethodXY(final Class type) {
    final List methods = new ArrayList();
    Class klass = type;
    while (klass != Object.class) { // need to iterated thought hierarchy in order to retrieve methods from above the current instance
        // iterate though the list of methods declared in the class represented by klass variable, and add those annotated with the specified annotation
        for (final Method method : klass.getDeclaredMethods()) {
            if (method.isAnnotationPresent(MethodXY.class)) {
                MethodXY annotInstance = method.getAnnotation(MethodXY.class);
                if (annotInstance.x() == 3 && annotInstance.y() == 2) {         
                    methods.add(method);
                }
            }
        }
        // move to the upper class in the hierarchy in search for more methods
        klass = klass.getSuperclass();
    }
    return methods;
}

For invocation of the found method(s) pls refer a tutorial. One of the potential difficulties here is the number of method arguments, which could vary between found methods and thus requiring some additional processing.