inner-classes

问题 There are some cases in Java where an inner class extends an outer class. For example, java.awt.geom.Arc2D.Float is an inner class of java.awt.geom.Arc2D, and also extends Arc2D. (c.f. http://download.oracle.com/javase/6/docs/api/java/awt/geom/Arc2D.Float.html) Also, sun.org.mozilla.javascript.internal.FunctionNode.Jump extends sun.org.mozilla.javascript.internal.Node, which is a superclass of FunctionNode. (sorry... cannot find a link to the javadoc) To me, this seems odd. Could you then

问题 I have three questions. To explain, I was reviewing someone's code, and noticed BufferedReader s sometimes aren't being closed. Usually, Eclipse gives a warning that this is a potential memory leak (and I fix it). However, within a Callable inner class, there is no warning. class outerClass { ... public void someMethod() { Future<Integer> future = outputThreadPool.submit(new innerClass(this.myProcess.getInputStream(), threadName)); ... } class innerClass implements Callable<Integer> { private

问题 I have three questions. To explain, I was reviewing someone's code, and noticed BufferedReader s sometimes aren't being closed. Usually, Eclipse gives a warning that this is a potential memory leak (and I fix it). However, within a Callable inner class, there is no warning. class outerClass { ... public void someMethod() { Future<Integer> future = outputThreadPool.submit(new innerClass(this.myProcess.getInputStream(), threadName)); ... } class innerClass implements Callable<Integer> { private

问题 In the following code class B has inherited yay attribute from class A , I expected this. I'd also expect that inner class B.Foo behaves the same way but it doesn't. How to make B.Foo to inherit alice attribute from class A ? I need that the inner subclass Foo in B has both the attributes alice and bob . Thanks. >>> class A: ... yay = True ... class Foo: ... alice = True ... >>> class B(A): ... nay = False ... class Foo: ... bob = False >>> B.yay True >>> B.Foo.alice Traceback (most recent

问题 This question already has answers here : Closed 7 years ago . Possible Duplicate: Why does Java prohibit static fields in inner classes? I was going through the specification and got that it is not possible to have the static member in the inner class which is not final compile time constant . class HasStatic { static int j = 100; } class myInnerClassTest { class Inner extends HasStatic { static final int x = 3; // OK: compile-time constant static int y = 4; // Compile-time error: an inner

问题 Consider the following code class OuterClass{ class InnerClass{ int x; int y; void calculateX(){ x = y+z;//I want to access the y field of the outer class } void printX(){ print(); } } int y; int z; InnerClass instance; OuterClass(int y,int z){ this.y = y; this.z = z; instance = new InnerClass(); instance.y = 10; instance.calculateX(); instance.printX(); } void print(){ System.out.println("X:"+instance.x+"\nY:"+y+"\nZ:"+z+"\n"); } } How to access field of the outer class if there is any

问题 App runs but the TextView doesn't get update here is the relevant code. activity_picker_dashboard.xml <android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto" android:layout_width="match_parent" android:layout_height="match_parent"> <!-- Top header --> <include layout="@layout/layout_header" /> This layout has databinding <!-- DrawerLayout --> <android.support.v4.widget.DrawerLayout android:id="

问题 This question already has answers here : Why is an anonymous inner class containing nothing generated from this code? (5 answers) Closed 2 years ago . I have compiled the following code (Methods and variables are elided for brevity): // Outer.java public class Outer { private class Inner { } void someMethod() { Inner inObj = this.new Inner(); } public static void main(String s[]) { Outer outerObj = new Outer(); } } When I listed the classes created, it displayed the following: Outer$1.class

问题 I'm using Eclipse and I've written a Java application using SWT. When Eclipse compiles my program, it renames my main file into 4 different files like this: MainFile.class MainFile$1.class MainFile$2.class MainFile$3.class When I go to run this program from command line, I get Could not find the main class: MainFile.class. Program will exit. I really don't understand why this is happening. 回答1: The $ classes are for anonymous inner classes and perfectly normal. Could we see the command line

问题 Method-Local inner class cannot access local variables because the instance of the method-local inner class may still alive after the method is over. But local variables will vanish once the local method is over. I learned that method-local inner class can access final local variable, does this mean final local variable still alive after the method is over? 回答1: Sort of. Java anonymous inner classes act like "closures," that is, they "close" around the current local state. However, Java only