com.blazebit.reflection.MethodParameter Maven / Gradle / Ivy

/*
 * Copyright 2011 Blazebit
 */
package com.blazebit.reflection;

import java.lang.annotation.Annotation;
import java.lang.reflect.Constructor;
import java.lang.reflect.Method;
import java.lang.reflect.Type;
import java.lang.reflect.TypeVariable;

/**
 * @author Christian Beikov
 */
public class MethodParameter {

    private Constructor constructor;
    private Method method;
    private int index;

    MethodParameter(Method method, int index) {
        if (method == null) {
            throw new NullPointerException("Method must not be null");
        }

        this.method = method;
        this.index = index;
    }

    MethodParameter(Constructor constructor, int index) {
        if (constructor == null) {
            throw new NullPointerException("Method must not be null");
        }

        this.constructor = constructor;
        this.index = index;
    }

    public Constructor getConstructor() {
        return constructor;
    }

    public int getIndex() {
        return index;
    }

    public Class getType() {
        return method != null ? method.getParameterTypes()[index] : constructor
                .getParameterTypes()[index];
    }

    public Class getResolvedType(Class concreteClass) {
        Type t = method != null ? method.getGenericParameterTypes()[index]
                : constructor.getGenericParameterTypes()[index];

        if (t instanceof TypeVariable) {
            return ReflectionUtils.resolveTypeVariable(concreteClass,
                    (TypeVariable) t);
        }

        return getType();
    }

    public Class[] getResolvedTypeParameters(Class concreteClass) {
        Type t = method != null ? method.getGenericParameterTypes()[index]
                : constructor.getGenericParameterTypes()[index];
        return ReflectionUtils.resolveTypeArguments(concreteClass, t);
    }

    public  T getAnnotation(Class annotationClass) {
        if (annotationClass == null) {
            throw new NullPointerException("annotationClass must not be null");
        }

        for (Annotation a : getAnnotations()) {
            if (annotationClass.isInstance(a)) {
                return annotationClass.cast(a);
            }
        }

        return null;
    }

    public Annotation[] getAnnotations() {
        return method != null ? method.getParameterAnnotations()[index]
                : constructor.getParameterAnnotations()[index];
    }

    public Method getMethod() {
        return method;
    }
}