Most of the time taken for 'direct' is the time taken to execute (). Method method =random.getClass().getMethod("next", paramClass) Public static void testSlowReflection() throws Exception Method method =random.getClass().getMethod("next", new Class) ĭouble d = (Double)method.invoke(random, params) Public static void testReflection() throws Exception Public static void testDirect() throws Exceptionĭouble start = System.currentTimeMillis() įor (int i = 0 i < NUMBER_OF_ITERATIONS i++) Static final int NUMBER_OF_ITERATIONS = 10000000 1.7K Training / Learning / CertificationĪ simple example that illustrates the performance impact of reflection.165.3K Java EE (Java Enterprise Edition).7.9K Oracle Database Express Edition (XE).3.8K Java and JavaScript in the Database.
Unfortunately, this rule is undocumented for a very good reason: it is completely unsupported and supposed to be for testing-purposes only. An object can be a class, a field, or a method. Thus a Reflection can be defined as a technique of inspecting and modifying the runtime behavior of an unknown object at run time. This directive overrides the limitations of normal inlining to inline method bodies which might not otherwise be considered. Java programming language provides a feature called Reflection that allows us to modify the runtime behavior of a class or field or method at runtime. While undocumented, this rule is supported by R8.Īnother undocumented, R8-specific rule can help guide inlinining is -alwaysinline. An example of this was shown in the value assumption post (and ProGuard has since come to add support for that rule!). But aside from honoring what ProGuard supports, it does have a undocumented rules of its own. R8 advertises its configuration rules as being compatible with those documented for ProGuard, the tool it’s meant to replace. The three method calls to getClass(), getSimpleName(), and the create() overload, along with specifying the arguments to those methods, exceeds the maximum allowed method body size for inline candidates. This example is no different in that regard, but it is different because the create(Activity) method is too large to be inlined normally. The inlining of method bodies has been a staple in previous R8 posts as it often unlocks optimizations that otherwise would not apply. This operation is not terribly expensive, but it is still a form of reflection.Ĭlass MyActivity extends Activity When dealing with an instance, the Class reference is obtained by calling getClass() instead of a MyActivity.class literal. This works great in a static context where the MyActivity.class literal is fixed, but it does not work when used on an instance. This was presented in the context of log tags, where you might write that expression instead of the string literal so that the tag always reflects the actual class name, even after obfuscation. RecordComponent is a new class in the package with eleven methods for retrieving things such as the details of annotations and the generic type. The getRecordComponents () method returns an array of RecordComponent objects. So let’s get back on track.Ĭlass constant operations allow R8 to take calls such as () and replace it with the string literal "MyActivity". The Class class has two methods isRecord () and getRecordComponents (). This was actually a detour from what I had promised was next at the end of the class constant operations post which preceded it. The previous post on R8 covered method outlining which automatically de-duplicated code. For an intro to R8 read “R8 Optimization: Staticization”. For an intro to D8 read “Android’s Java 8 support”.
USING JAVA REFLECTION TO DISABLE METHODS SERIES
Note: This post is part of a series on D8 and R8, Android’s new dexer and optimizer, respectively. R8 Optimization: Class Reflection and Forced Inlining
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