inner-classes

问题 Can we create an object of the inner class in the constructor of the outer class? 回答1: Sure. public class Outer { public Outer() { Inner inner = new Inner(); } class Inner { } } 回答2: Yes it's legal to construct an inner class in constructor of outer class. For example: public class Outer { private Inner myInner; public Outer() { myInner = new Inner(); } public class Inner { } } Have a read through the Sun Nested Classes Tutorial. 回答3: If I understand you correctly, then yes, if your using

问题 I have a simple form setup and I was following how the book, Core Java Vol I, sets up their forms, where they have a top level class that extends JFrame create objects of the different components, and lays them out in the frame. If this isn't the way you are "typically" supposed to do it, please let me know. I got confused when I wrote my inner classes to perform actions when buttons were pressed. I could put my inner class in my AddressBookForm class since that's where I put my buttons and

问题 I want to check if the user liked post or not, so I wrote this function and it needs to return boolean value. Any trick or hint would be appreciated. Thanks so much, everyone. public boolean ImLike (String Url ) { // Check If user Like The Post Before requestQueue = Volley.newRequestQueue(context); requestQueue.start(); final boolean[] flag = new boolean[1]; StringRequest request = new StringRequest(Request.Method.GET, Url, new Response.Listener<String>() { @Override public void onResponse

问题 When I define the following class public class Outer extends Outer.Inner { public static class Inner { } } Netbeans 6.9.1 gives me the "has no definition of serialVersionUID" warning for both Outer and Inner. I'm wondering if there is a legit reason for this warning, or if it's a bug. What about extending an inner class makes the compiler think they are implementing Serializable? Note: This is more out of curiosity than wanting this unnecessary design pattern. 回答1: I've wondered the same

问题 I'm trying to subclass an inner class (defined in Java) in Rhino, and I can't seem to make it work. I've got some compiled Java code (which I essentially can't change) that has an inner abstract class: package mypackage; class MyClass { abstract static class MyInnerClass { abstract void print(String s); } } From Rhino, I can see it just fine: js> Packages.mypackage.MyClass.MyInnerClass [JavaClass mypackage.MyClass$MyInnerClass] But I can't figure out how to subclass it. I figured something

问题 I just got some bad feedback on a uni project and need some impartial clarification; Can anyone explain when I should use (anonymous) inner listener classes vs components that listen to themselves? (a vs b) a) public class myButton extends JButton { public myButton() { addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { // handling code... } }); } } b) public class myButton extends JButton implements ActionListener { public myButton() { addActionListener(this

问题 I am using Qt5 with the VS2013 compiler. I am trying to nest two classes CUDial and DUDial in the same outer class UDial . UDial is a QDialog type class. I would like CUDial and DUDial to be both of QWidget type. It for use with a QTabWidget variable in the outer class. So, I write the code as follow: class UDial : public QDialog { Q_OBJECT class CUDial : public QWidget { Q_OBJECT // Some variables public: CUDial(QWidget *parent = 0); }wid1; class DUDial : public QWidget { Q_OBJECT // Some

问题 We have some particular functionality implemented as a Python class, in order to be easily extended by our developers inheriting it. Each class has a an inner Config class with a list of items. The base class has an empty Config class, and each inheriting class defines some items into it. Then pylint complains each time the item of Config subclass is used. For example, this code: class A(object): class Config(object): def __init__(self): self.item1 = 1 self.item2 = 2 def __init__(self): self.

问题 The class ExtendedDismaxQParser has a static member class Clause: public class ExtendedDismaxQParser { protected static Class Clause { protected String foo, bar; } public Clause getAClause { Clause c; // misc code that isn't important return c; } } I then extended this class in a different package: public class SpecialDismaxQParser extends ExtendedDismaxQParser { public void whatever() { Clause c = super.getAClause(); boolean baz = c.foo.equals("foobar"); // <-- This doesn't compile } } It

问题 Java lets you declare new fields inside anonymous classes, but I can't figure out how to access them from outside, even setting them to public doesn't let me. class A { public static void main(String[] args) { Object o = new Object() { public int x = 0; { System.out.println("x: " + x++); System.out.println("x: " + x++); } }; System.out.println(o.x); } } I get this compiler error: $ javac A.java && java A A.java:10: cannot find symbol symbol : variable x location: class java.lang.Object System