![]() ![]() Returns a Method object that represents a declared method of the target Class object with the signature specified by the second parameters Returns an array of Method objects that represent all of the public methods (either declared or inherited) supported by the target Class object Returns a Method object that represents a public method (either declared or inherited) of the target Class object with the signature specified by the second parameters Table 1.1 The methods defined by Class for method query Method This seems fine for methods that take objects as parameters, but what about types not created by a class declaration? For example, getMethod from listing 1 uses an array of Class to indicate the types of the parameters of the desired method. The discussion of the methods from table 1 indicates that Java reflection uses instances of Class to represent types. As such a method does exist in the Test class, a valid MethodInfo is returned and the Invoke method executes it successfully.Editor’s Note: This piece picks up where the article Java Reflection in Action left off.] 1.5 Representing types with class objects The parameters are, in order, a string and an integer. The third line uses reflection to find a method that has the name, "ShowMessage", and that includes two parameters. The first item in the array must correspond to the first parameter of the desired method with subsequent array elements matching the remaining parameters in the order in which they appear.įor example, try adding the following code to the Main method of the program. This contains an array of Type instances. To provide the desired parameter types, a second argument is added to the call to GetMethod. We don't need to specify the return type for the method, as it's illegal in C# to create overloads whose signatures differ only by their return types. To avoid this problem you need to specify the types of the parameters of the target method, as well as its name. If you try to run it, the program will throw an AmbiguousMatchException, indicating that there is more than method with that name. With our test class, the above call is invalid. MethodInfo method = type.GetMethod("ShowMessage") ![]() Let's consider an example class, shown below: If the method that you wish to invoke is overloaded, the manner of obtaining a MethodInfo instance must be modified. If the method being called has parameters, you pass values to these via an array of objects. Finally, you use the Type class's Invoke method to execute the code. Next, you can call GetMethod on the Type object to obtain details of the method, held in a MethodInfo object. Firstly you must obtain a Type object to represent the class or structure containing the method you wish to execute. The basic process that you follow in order to invoke a method using reflection has several steps. You can even call non-public methods, though this should be a last resort, as those methods may be unexpectedly refactored during updates, making them unavailable. Using the techniques described in those earlier articles you can call the methods of late-bound objects. Invoking Methodsĭuring the Reflection tutorial I described the basic ways in which you can reflect the methods of a type and invoke those methods. When invoking overloaded methods, the call to obtain the method information must be modified. Static and instance methods can be invoked via reflection by obtaining a MethodInfo object for the desired member and calling the Type class's Invoke method. ![]()
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