tasks/astrid/common-src/com/localytics/android/ReflectionUtils.java

/**
 * Copyright (c) 2012 Todoroo Inc
 *
 * See the file "LICENSE" for the full license governing this code.
 */
package com.localytics.android;

import java.lang.reflect.InvocationTargetException;

/**
 * Static utilities for performing reflection against newer Android SDKs.
 * <p>
 * This is not a general-purpose reflection class but is rather specifically designed for calling methods that must exist in newer
 * versions of Android.
 */
public final class ReflectionUtils
{
    /**
     * Private constructor prevents instantiation
     *
     * @throws UnsupportedOperationException because this class cannot be instantiated.
     */
    private ReflectionUtils()
    {
        throw new UnsupportedOperationException("This class is non-instantiable"); //$NON-NLS-1$
    }

    /**
     * Use reflection to invoke a static method for a class object and method name
     *
     * @param <T> Type that the method should return
     * @param classObject Class on which to invoke {@code methodName}. Cannot be null.
     * @param methodName Name of the method to invoke. Cannot be null.
     * @param types explicit types for the objects. This is useful if the types are primitives, rather than objects.
     * @param args arguments for the method. May be null if the method takes no arguments.
     * @return The result of invoking the named method on the given class for the args
     * @throws RuntimeException if the class or method doesn't exist
     */
    public static <T> T tryInvokeStatic(final Class<?> classObject, final String methodName, final Class<?>[] types, final Object[] args)
    {
        return (T) helper(null, classObject, null, methodName, types, args);
    }

    /**
     * Use reflection to invoke a static method for a class object and method name
     *
     * @param <T> Type that the method should return
     * @param className Name of the class on which to invoke {@code methodName}. Cannot be null.
     * @param methodName Name of the method to invoke. Cannot be null.
     * @param types explicit types for the objects. This is useful if the types are primitives, rather than objects.
     * @param args arguments for the method. May be null if the method takes no arguments.
     * @return The result of invoking the named method on the given class for the args
     * @throws RuntimeException if the class or method doesn't exist
     */
    public static <T> T tryInvokeStatic(final String className, final String methodName, final Class<?>[] types, final Object[] args)
    {
        return (T) helper(className, null, null, methodName, types, args);
    }

    /**
     * Use reflection to invoke a static method for a class object and method name
     *
     * @param <T> Type that the method should return
     * @param target Object instance on which to invoke {@code methodName}. Cannot be null.
     * @param methodName Name of the method to invoke. Cannot be null.
     * @param types explicit types for the objects. This is useful if the types are primitives, rather than objects.
     * @param args arguments for the method. May be null if the method takes no arguments.
     * @return The result of invoking the named method on the given class for the args
     * @throws RuntimeException if the class or method doesn't exist
     */
    public static <T> T tryInvokeInstance(final Object target, final String methodName, final Class<?>[] types, final Object[] args)
    {
        return (T) helper(target, null, null, methodName, types, args);
    }

    @SuppressWarnings("unchecked")
    private static <T> T helper(final Object target, final Class<?> classObject, final String className, final String methodName, final Class<?>[] argTypes, final Object[] args)
    {
        try
        {
            Class<?> cls;
            if (classObject != null)
            {
                cls = classObject;
            }
            else if (target != null)
            {
                cls = target.getClass();
            }
            else
            {
                cls = Class.forName(className);
            }

            return (T) cls.getMethod(methodName, argTypes).invoke(target, args);
        }
        catch (final NoSuchMethodException e)
        {
            throw new RuntimeException(e);
        }
        catch (final IllegalAccessException e)
        {
            throw new RuntimeException(e);
        }
        catch (final InvocationTargetException e)
        {
            throw new RuntimeException(e);
        }
        catch (final ClassNotFoundException e)
        {
            throw new RuntimeException(e);
        }
    }
}