nested-class

问题 Given what I know of every other type of static feature of programming––I would think the answer is 'no'. However, seeing statements like OuterClass.StaticNestedClass nestedObject = new OuterClass.StaticNestedClass(); makes me wonder. 回答1: Yes, there is nothing in the semantics of a static nested type that would stop you from doing that. This snippet runs fine. public class MultipleNested { static class Nested { } public static void main(String[] args) { for (int i = 0; i < 100; i++) { new

问题 Given what I know of every other type of static feature of programming––I would think the answer is 'no'. However, seeing statements like OuterClass.StaticNestedClass nestedObject = new OuterClass.StaticNestedClass(); makes me wonder. 回答1: Yes, there is nothing in the semantics of a static nested type that would stop you from doing that. This snippet runs fine. public class MultipleNested { static class Nested { } public static void main(String[] args) { for (int i = 0; i < 100; i++) { new

问题 Is declaring a class that extends Activity inside another Activity class possible? If it is, how would I register that class in the manifest? Also, is that something that can be reasonably done or is it a bad idea? I was thinking of something like class ListClass extends ListActivity{ ... ArrayList items; class ItemClass extends Activity{ ... Item item; @Override onCreate(){ Integer pos = getIntent().getExtras().getInt("pos"); item = items.get(pos); } } @Override onItemClick(int position){

问题 Is declaring a class that extends Activity inside another Activity class possible? If it is, how would I register that class in the manifest? Also, is that something that can be reasonably done or is it a bad idea? I was thinking of something like class ListClass extends ListActivity{ ... ArrayList items; class ItemClass extends Activity{ ... Item item; @Override onCreate(){ Integer pos = getIntent().getExtras().getInt("pos"); item = items.get(pos); } } @Override onItemClick(int position){

问题 The java compiler allows me write a Class definition inside an Interface . Are there any specific uses of this ? interface ClassInterface { void returnSomething(); int x = 10; class SomeClass { private int y; private void classDoingSomething() { } } } Please explain . 回答1: You would use it to tightly bind a certain type to an interface. Read This page for further information and an example of defining a class inside an interface. 回答2: The uses are the same that a class nested in another class

问题 The java compiler allows me write a Class definition inside an Interface . Are there any specific uses of this ? interface ClassInterface { void returnSomething(); int x = 10; class SomeClass { private int y; private void classDoingSomething() { } } } Please explain . 回答1: You would use it to tightly bind a certain type to an interface. Read This page for further information and an example of defining a class inside an interface. 回答2: The uses are the same that a class nested in another class

问题 In java what are nested classes and what do they do? 回答1: They're just classes within other classes. They make it possible to have a hierarchy of classes, and if you make them private they're a convenient way to encapsulate data that isn't exposed outside of the class using them. Sun has a short tutorial about them 回答2: One of the most important uses of inner classes in Java are listeners. Instead of writing an entire separate class for an ActionListener or similar, you create it in-place:

问题 This question already has answers here : Why is an anonymous inner class containing nothing generated from this code? (5 answers) Closed 4 years ago . In the below code : class EnclosingClass { public static class BiNode extends Sub.IBiLink { } private static class Sub { private static class IBiLink { } } } On compiling along with other .class files, I also see a file named "EnclosingClass$1.class" .Why has this been automatically created? Whats going on? 回答1: First have a look at the class

问题 I've seen a few "solutions" to this, but the solution every time seems to be "Don't use nested classes, define the classes outside and then use them normally". I don't like that answer, because it ignores the primary reason I chose nested classes, which is, to have a pool of constants (associated with the base class) accessible to all sub-class instances which are created. Here is example code: class ParentClass: constant_pool = [] children = [] def __init__(self, stream): self.constant_pool

问题 I have a class C with some internal variables. It has a nested class N that wants to access the variables in C. Neither C nor N are static, although C has some static methods and variables. When I try to access a non-static variable in C from N I get the squiggly underline and the message "Cannot access non-static field [fieldname] in static context". This seems to have something to do with the nested class, since I can access the variable fine from the enclosing class itself. ReSharper