inner-classes

问题 i cant create B-Object, but why? public class AFactory { public int currentRange; private abstract class A { protected final Object range = currentRange; public int congreteRange = 28; } public class B extends A { public int congreteRange = 42; } synchronized A createNew(Class<? extends A> clazz) throws Exception { // EDIT: there is accessible default constructor currentRange = clazz.newInstance().congreteRange; return clazz.newInstance(); } public static void main(String[] args) throws

问题 What I want to do is when onSuccess method executed, the queryLogin return true ,while if onFailuer method executed , the queryLogin return false ; But as you know, in java, I cannot modify an outer class value from the inner class. So I just wonder how can I solve the problem and achieve my aim. public static boolean queryLogin(String username, String passowrd){ boolean isSuccess = false; params.put("username", username); params.put("password", passowrd); VStarRestClient.post(LOGIN_URL,

问题 The Java Tutorial says that since an inner class is associated with an instance of the enclosing class, it (the inner class) cannot define any static members itself. It's interesting for me why can't inner classes declare static members for instance, some private static field, which the instance of this inner class could possibly share with the other instances of the same inner class? is this just an implementation of things in Java that has to be taken for granted or something else? 回答1:

问题 I have to do an unrolled linked list for one of my classes. I'm new to python, but not to programming, and for some reason I cannot get around this little problem! I have a class Node that is to be the node object used within the unrolled linked list. The unrolled linked list class performs all the operations on the Node class. class UnrolledLinkedList(object): """ INNER NODE CLASS """ class Node(object): def __init__(self): self.array = [] self.next_node = None """ END NODE CLASS """ def _

问题 I have inner class in my code. I want to give public access to its instances, but only outer class should be able to create this instances, like in "private" access. Is it possible without making properly small package (or creating public interface for every such inner class)? (Sorry if my english is bad :P) 回答1: It is possible. Declare your inner class public, but its constructor private . This way you can create it only inside your enclosing class and itself, but not from outside. 回答2: By

问题 Although I'm not currently planning to serialize anything, I give all serializable outer classes, as well as static nested classes a SerialVersionUID , because that is the proper way to do it. However, I've read here that Serialization of inner classes (i.e., nested classes that are not static member classes), including local and anonymous classes, is strongly discouraged for several reasons. ... So my question is: Should I give inner and anonymous classes a SerialVersionUID each, or should I

问题 Although I'm not currently planning to serialize anything, I give all serializable outer classes, as well as static nested classes a SerialVersionUID , because that is the proper way to do it. However, I've read here that Serialization of inner classes (i.e., nested classes that are not static member classes), including local and anonymous classes, is strongly discouraged for several reasons. ... So my question is: Should I give inner and anonymous classes a SerialVersionUID each, or should I

问题 Why can we have static final members but cant have static method in an non static inner class ? Can we access static final member variables of inner class outside the outer class without instantiating inner class ? 回答1: YOU CAN have static method in a static "inner" class. public class Outer { static String world() { return "world!"; } static class Inner { static String helloWorld() { return "Hello " + Outer.world(); } } public static void main(String args[]) { System.out.println(Outer.Inner

问题 Is it possible to serialize a non Static Inner class? If yes can you provide a good example. I googled through few blogs and sites non of answer convinced me. EDIT: How about the inner class having final staic variable. 回答1: Inner class contains an implicit reference to the outer class, so for an inner class to be serializable its outer class must be as well. Exactly from docs: Serialization of inner classes (i.e., nested classes that are not static member classes), including local and

问题 Can someone tell me what the purpose of having inner classes? I can think of a few but may be they are not good reasons for using inner classes. My reasoning is that inner class is helpful when you want to use a class that no other classes can use. What else? 回答1: Inner classes can be used to simulate closures: http://en.wikipedia.org/wiki/Closure_(computer_science)#Java 回答2: When I was learning Java we used inner classes for GUI event handling classes. It is sort of a "one time use" class