anonymous-class | 易学教程

Accessing container fields

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问题 I've got a very silly question to ask. I'm using NetBeans to built a small app and I'm having the following problem; My main class is called mainApp and is extending a JFrame which in turn contains a JPanel called drawingBoard which I also extend for various (and off-topic) reasons.. The core problem is that at some point I need to access one of the fields of the mainApp but due to the way NetBeans instantiates my main class..(as anonymous class) I can't get a reference to the container(that

golang anonymous field of type map

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问题 I thought I'd be able to make an ordered map type by using anonymous fields: type customMap struct{ map[string]string ordered []string } where I could reference the map with customMapInstance["key"] and iterate over ordered . Alas, it appears arrays and maps are not valid anonymous fields. I suspect there's a good reason... 回答1: From the spec: An embedded type must be specified as a type name T or as a pointer to a non-interface type name *T, and T itself may not be a pointer type. You see

Anonymous class question

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问题 I've a little doubt over this line: An anonymous class cannot define a constructor then, why we can also define an Anonymous class with the following syntax: new class-name ( [ argument-list ] ) { class-body } 回答1: You are not defining a constructor in anonymous class, you are calling a constructor from superclass. You can't add a proper constructor for anonymous class, however, you can do something similar. Namely an initialization block. public class SuperClass { public SuperClass(String

access exception when invoking method of an anonymous class using java reflection

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问题 I'm trying to use an event dispatcher to allow a model to notify subscribed listeners when it changes. the event dispatcher receives a handler class and a method name to call during dispatch. the presenter subscribes to the model changes and provide a Handler implementation to be called on changes. Here's the code (I'm sorry it's a bit long). EventDispacther: package utils; public class EventDispatcher<T> { List<T> listeners; private String methodName; public EventDispatcher(String methodName

Serializing anonymous classes with Gson

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问题 Is there any reason to why you cant serialize anonymous classes to Json? Example: public class AnonymousTest { private Gson gson = new Gson(); public void goWild() { this.callBack(new Result() { public void loginResult(Result loginAttempt) { // Output null System.out.println(this.gson.toJson(result)); } }); } public void callBack(Result result) { // Output null System.out.println(this.gson.toJson(result)); result.loginResult(result); } public static void main(String[] args) { new

How are anonymous classes compiled in Java?

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问题 I've heard that Java bytecode actually doesn't support any kind of unnamed classes. How does javac translate unnamned classes to named ones? 回答1: It synthesizes a name of the form EnclosingClass$n , where "n" is a counter for anonymous classes in EnclosingClass . Because using $ in identifiers is discouraged, these names should not collide with any user-specified names. 来源： https://stackoverflow.com/questions/5808492/how-are-anonymous-classes-compiled-in-java

Why is an anonymous class in a static context valid

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问题 I have a misunderstanding about what an anonymous class in Java is. Consider the following simple example: public static void main (String[] args) throws java.lang.Exception { B b = new B(){ }; System.out.println(b.b); } interface B{ int b = 1; } DEMO Why does the code compile? The JLS, chapt 15 says: An anonymous class is always an inner class (§8.1.3); it is never static But the JLS, chapt 8 An inner class is a nested class that is not explicitly or implicitly declared static. So the

(JAVA Enums) - Anonymous class inside enum constant

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Good day! I have an interface which only implements one single method. I dont feel like making several class which all implement this one single method therefore I decided to use anonymous classes instead. I use enums for certain static items, these enums have instances of my interface. However, when I try to make an anonymous class inside my enum constants my IDE (eclipse) literally tells me nothing (as if it is outside a code block). My question is as follows: Can I use anonymous classes inside my enum constants? If my text was unclear (Sorry im not english) please see the example below.

Reference to final object in anonymous class constructor a leak?

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问题 I'm passing a runnable to a service. The runnable duration may outlive the fragment / activity that passes it. I'm wondering if the following code snippet would leak the frag object by maintaining a reference inside the runnable? I realize I can move the whole line containing frag outside of the runnable (like I did with "String key = frag..."), but I'm asking simply to get an understanding of how/when an anonymous class would leak an object. I'm really not certain. The runnable only needs

Creating a dynamic anonymous types variables

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问题 Can I create an anonymous type variable and later on add more Properties? E.g. var x = new { Name = "Ahmed" }; and want to add Age to it? how can I do this? Another question: i saw on some blogs a type AnonymousType what is the name space for this class? here is am example http://www.codeproject.com/KB/cs/AnonymousTypesInCSharp.aspx 回答1: First question - you can't. Second question - AnonymousType is the type the author of that article created. You have to download the source for his project