(Java question)
If I reference a field in an inner class, does this cause a circular dependency between the enclosing class and the inner class?
How can I avoid this?
Here is an ... |
Sorry for the bad title, but I couldn't think of a better one.
I'm having a class A and a class B which is kind of a sub class of A, like ... |
Can someone please explain to me what is the difference between protected / public Inner classes?
I know that public inner classes are to avoid as much as possible (like explained in ... |
I'm translating programs of some language to nested java classes. At some point, the level of nesting becomes so deep that I get:
compiling Test.javaTest.java:5179: error while writing : Test$2...$1.class (File name ... |
Are inner classes commonly used in Java? Are these the same as nested classes? Or have these been replaced in Java by something better? I have a book ... |
I'm obfuscating a library with ProGuard using the Ant task.
I'm keeping particular class names and their method names when they have a particular annotation (@ApiAll) and I'm requesting that the InnerClasses ... |
Why did Java's designers consider it useful/necessary?
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I coded in NetBeans something like this:
public class Grafo<V, E>
{
class Par
{
int a, b;
...
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Recently the security team on my project released a secure code guidelines document, designed to be used as part of our code reviews. The first thing that struck me was an ... |
I'm new to Java and have the following question regarding inner classes:
When implementing an inner class, do I need to declare its attributes and methods scope i.e. public, private, protected?
EDIT: With ... |
Is it possible to get a reference to this from within a Java inner class?
i.e.
Class outer {
void aMethod() {
NewClass newClass = new NewClass() {
...
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I want a static inner class that can't be instantiated even by the external class. Right now I just have a documentation that says "Please don't instantiate this object". Can I ... |
This is what I'm doing now. Is there a better way to access the super class?
public class SearchWidget {
private void addWishlistButton() {
...
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I have a code like this:
class Foo() {
time_to_play = 0
class Bar() {
void change_player() {
...
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i wanted to use my java code as beanshell script but beanshell throws Exception saying class not found in namespace. Isn't there inner class in beanshell or does it have any ... |
I have a lot of objects of type ContainedClass stored in an object of type ContainingClass. I need to access the container object from the inside objects. As of now I ... |
I can understand what inner class is and how to write program. My question is in what situation do programmers really need inner class?
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Some might like to argue that this is a candidate for the least important issue of all times. Yet code style is a very important topic for me, and I want ... |
Good day!
I am making a keyboard-like buttons for my Hangman game (SEE PICTURE HERE), my problem is about the inner classes. I've read this LINK about inner classes and ... |
I have some situation that I want to use inner class of another class in another class.
like...
public class ListData {
public static class MyData {
...
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I have an inner class which is present inside a method and this class has a method.
I want to use the method which is present in my inner class method outside ... |
In class targte folder, found a lot of class1$class2, are those inner classes?
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In my own classloader i get all entries from jar file and use defineClass() to load classes to memory.
My problem is that if jar has inner classes (e.g. MyClass$1.class) the defineClass ... |
I have this method (in my own classloader) that loads classes from zip:
ZipInputStream in = new ZipInputStream(new FileInputStream(zip));
ZipEntry entry;
while ((entry = in.getNextEntry()) != null) {
if (!entry.isDirectory()) {
...
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The inner class is always inside the outer class and if we remove outer class then the inner class would also be destroyed. I don't think about memory release, I am ... |
I've just read through the chapter on method-local inner classes in the SCJP book, and I'm really struggling to think of any practical use for them.
I've always been under ... |
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I have class A with its inner class defined A1 and class B with its inner class defined B1. Do you think it is alright that class A in its implementation ... |
Possible Duplicate:
Usage of inner class
Dear folks,
I am relatively new to java i am studying inner classes. i have read a little bit though, but ... |
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public class Constant {
......
public enum Status {
ERROR,
WARNING,
NORMAL
}
......
}
After compiling I got a ... |
after messing around with parsing a JSON response with GSON for a day, I finally figured out how to get my javabeans right in order to extract my data from the ... |
Sorry , my question was not pretty clear for most of you. So this time i am just copying the book line .
I read one statement in SCJP 1.5 Book.
" ... |
I have a program where I compile java code that somebody writes in a text box, and run it.
They type out the full source code, class and all
I save the class ... |
Having the following code:
public class Main {
private Main() {}
class Test extends Main {
...
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I have a Class Aouter, This Aouter class has 2 inner classes namely Binner,Cinner. My doubt is if Binner class had been changed so Cinner class also should be compiled and ... |
Hi I tried below code while learning Java inner class. So surprising it passed compilation but could not work in run-time. My understanding is for inner class it must be instantiated ... |
This is regarding java. This is question asked in a interview.
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I am trying to use an inner class setup, however I'm having some problems. This is the code I'm trying to use:
public class GUI
{
class ButtonHandler implements ActionListener
...
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I'm using Intellij 10.5 and I'd like to be able to use the automatic generation of import lines to allow for inner classes, but I don't see it as a settings ... |
The following program uses an inner class named Anonymous which itself extends its enclosing class Main.
package name;
public class Main
{
private final String name;
Main(String name)
...
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P: 70 rotaryfreak Hi everyone, My classes are: Employee, Date and HourlyEmployee. I'm supposed to write my Employee class with Date class as an Inner class and then HourlyEmployee is supposed ... |
I have two public interface that extends Remote public interface InnerInterface extends Remote {} public interface OuterInterface extends Remote {} I then have a class (Outer) that contains an inner class that implements the InnerInterface... Something like this: public class Outer extends UnicastRemoteObject implements OuterInterface { public InnerInterface inner getInnerObject(); private class Inner extends UnicastRemoteObject implements InnerInterface { } } So ... |
class ClassOne { protected void methodOne() { System.out.println("One"); } } class ClassTwo { protected void methodTwo() { System.out.println("Two"); } } class Enclosing extends ClassOne { class Inner extends ClassTwo { void innerMethod() { methodOne(); methodTwo(); } } } public class TestMultiple { public static void main(String[] args) { Enclosing.Inner i = new Enclosing().new Inner(); i.innerMethod(); } } |
Do you mean "real time" as in real-time computing or "real world", meaning a concrete example? If you mean the latter, I once used an inner class to implement a linked list. Linked lists are made up of node which contain a data reference and pointers to other nodes in the list. Since the user of the linked list is interested ... |
Hi am tryint to figure out wat this sun's java tutorial is talking about. cant seem to put my finger on it... please explain the following para in more detail does the paragraph say that there can only be one active iterator for the Stack class. or that and also why does implementing the iterator as in inner class solve the ... |
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Hi all, I have the following code segment: It has a "Manager" class with an inner class called "KeyValue". Another class named "Caller" tries to instantiate an object of type Manager. The Eclipse debugger showed gave a ClassNotFoundException at the 1. public class Manager{ 2. public class KeyValue { 3. protected Object element; 4. protected Object value; 5. public KeyValue(Object element, ... |
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A clearer problem statement would be nice. I guess what the original poster wants to know is how can one obtain access to the instance of the enclosing class's methods and data, like an inner class does? An inner class has an implicit member field containing a reference to the instance of the enclosing class. If you don't want to use ... |
This is one of the versions of BeeServlet from the CattleDrive assignments on Servlets. I'm planning on using this as the model for my code, but I'm wondering why Default is coded as an inner class. (Though I'm copying, I figure I should still know why I'm doing what I'm doing!) package com.javaranch.drive ; import com.javaranch.common.* ; public class BeeServlet extends ... |
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class Outer { private String foo = "Outer.foo"; private String bar = "Outer.bar"; private Inner1 inner1 = new Inner1(); private Inner2 inner2 = new Inner2(); private class Inner1 { private String bar = "Inner1.bar"; Inner1() { System.out.println("new " + getClass().getName() + ": "); System.out.println(" foo=" + getFoo()); System.out.println(" bar=" + getBar()); } String getFoo() { return foo; } String getBar() { ... |
Hi, Can any of you explain the following program. //: c08:BigEgg2.java // Proper inheritance of an inner class. // From 'Thinking in Java, 3rd ed.' (c) Bruce Eckel 2002 // www.BruceEckel.com. See copyright notice in CopyRight.txt. import com.bruceeckel.simpletest.*; class Egg2 { protected class Yolk { public Yolk() { System.out.println("Egg2.Yolk()"); } public void f() { System.out.println("Egg2.Yolk.f()");} } private Yolk y = new ... |
Hi, The main method uses the reflection API to access the method of a private inner class. Since InnerClass is a private member it should not be accessible from the class Test. It maynot be a compile time error since the class is not used anywhere but I feel like there should be a runtime check. Can someone explain something that ... |
Hi, we can declare an inner class as abstract or final. Then where and how we can impliment the abstract methods of an inner class and what is the meading of making an inner class final. Similary if we declare an inner class as method local with abstract or final then where and how we can impliment the abstract methods of ... |
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hi i did go through the explaination, this is my understanding line1 in the given code is as good as putting it as following void makebar(){ Bar a =new bar(){ }; a.go(); } in which case the makebar method creats method local anonymous subclass of Bar,which calls the inherited go()method of the superclass(Bar). iam i correct in saying so. |
I ran into the problem with static data in an inner class recently. This site Nested Classes gives a good short description of inner classes. A non-static inner class is associated with an instance of a class, not the class itself. That's why the inner class can access "this" for the enclosing class. So declaring something static in the inner class ... |
Hi Guys ! I am not able to understand this code for inner class. If anybody can please help me in this as to what will be the flow of this Code. public Iterator selectByDates(PrimaryKey errorCode, final java.util.Date startDate, final java.util.Date endDate) throws FindException { if (logger.isDebugEnabled()) { logger.debug("selectByDates(" + errorCode + ", " + startDate + ", " + endDate ... |
package testing; class TopClass { public InnerClass makeInnerInst() { return new InnerClass(); } public class InnerClass { public InnerClass() { } } } public class TopLevelClass { public static void main (String[] args) { TopClass tlcObj = new TopClass(); TopClass.InnerClass = new tlcObj.makeInnerInst(); // Line 16 TopClass.InnerClass = tlcObj.new InnerClass(); // Line 17 } } |
That is a big question, and I agree the tutorial would be in order. But for a quick introduction I can say that sometimes there's the need to do your implementation right there... on the spot. Yes, you could have a separate class, instantiate it, and use it, but if you're just going to throw it out immediately anyway, and it's ... |
Please be more verbose, I can hardly understand what you're asking for, exactly. Inner-classes are a bit intricate, but they're very well covered in the Certified Java Programmer study books, so you might want to read the chapter on inner classes in one of those. Basically, and inner class is a class defined inside some other class (but you knew that). ... |
In the following code class outer{ static int a; static final int b; static final int c=1; static{ b = 2; } class inner{ static final int x = a; static final int y = b; static final int z = c; } } I get 2 errors global.java:10: inner classes cannot have static declarations static final int x = a; ... |
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My inner class is a simple JPanel with JTextField and JButton. When I instantiate it from within its enclosing class, I just see a gray square. class ActorEdit implements ActionListener { JFrame fr = new JFrame(); JTextField actorBox = new JTextField(); JButton valider = new JButton("Valider"); Container pane = fr.getContentPane(); ActorEdit() { fr.setSize(new Dimension(250, 700)); fr.setUndecorated(true); fr.setLocation(500, 125); fr.setAlwaysOnTop(true); fr.setVisible(true); fr.validate(); ... |
I'm still trying to understand these inner classes In the following section of code, java does not allow me to use ip in the inner class. public void run(ImageProcessor ip) { copy = new Button(); copy.addActionListener(new ActionListener(){ public void actionPerformed(ActionEvent e){ ip1 = ip.crop(); } }); } the IDE says that it "Cannot refer to a non-final variable ip inside an ... |
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Yes, that rule applies to all classes. (And it applies to all interfaces, not just Serializable.) A nested class is a class so that rule applies to it. Unless you were thinking that the application of the rule would be "If a class implements an interface then all classes nested in it automatically implement that interface". That is not what the ... |
Hi, Perhaps I'm going about this entirely the wrong way (in which case please inform me of this!); but assuming I'm on the right track, I can't for the life of me figure out how to properly encapsulate the details of my inner class through delegate methods in the outer class. Here's the example code: package some.package; Public Class OuterClass { ... |
hello, one of the typical situations where an inner class seems to be appropriate to me are typical factories (Factory Method, Abstract Factory or Builder pattern). By making the class which implements the exposed interface a private inner one (usually static), it is ensured that the one objective of the corresponding pattern is accomplished: To encapsulate instance control. If the implementing ... |
Inner classes are not inevitable. There are programming languages that do not have inner classes and that doesn't mean that there are certain things you can't do in those languages. Just like inner classes you can find many other features of Java that are not inevitable - but that doesn't mean that inner classes or those other features are not useful ... |
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Hi, When switching to Java 6 from Java 1.4, a piece of code stopped compiling. The piece of code looks alright to me, and it ran fine under Java 1.4, suggesting a compiler bug. However, possibly I have missed some subtle reason why the code is illegal. To make it easy for Ranchers, I have written a tiny piece of code ... |
One common use of inner classes is as ActionListeners for Swing buttons, etc. This way, you can create a separate event handler for each button (or or menu or whatever), but have all of the code in one class (i.e., for the screen). Sometimes this is done with anonymous inner classes as well (i.e., where the inner class is created on ... |
Does anyone can give a good example? what I am doing? A.class A library = new A(); library.setAanpctlg_aadpctlx( ?); //here, how to pass to B.class through C class B.class has { public setValue( BPARM p){ } public class BPARM { public String _isbn; public String _ean; public String _ship_to; public String _department_code; } } Chelper.class has public interface Chelper{ public void ... |
Hi, I am getting java.lang.IllegalAccessError when i try to access an anonymous inner class from within the same class. The stack trace gives this message: java.lang.IllegalAccessError: tried to access class InnerOne from class OuterOne A note that I'd like to add here is that the OuterOne class has been loaded using my own implementation of the findClass() method of ClassLoader class. ... |
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I dont find any advantage of using inner classes besides its difficult to remember the complex syntax and hard to read code. I can always create a normal class, put the functionality there , create a instance and use it , in place of inner class. What are the advantages of inner class? Thanks Deepak |
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Hi, I have a doubt regarding inner class. Basically I want to access an parent class instance variable from inner class. It works fine if I do from inside a function. But if I want to modify a parent class instance variable while instantiation, it fails to compile. Please see the following codes. public class Outer { int i = 3; ... |
Hi, I was just working on inner classes and want to know how to instantioate an inner class, In the book its given as MyOuter.MyInner innerObj = new MyOuter().new MyInner(); But the way i instantiated is MyInner innerObject = new MyOuter().new Inner(); Are the two declarations have the same effect or is there a diiference in them. Plese reply asap. Below ... |
Hi, I am preparing for the SCJP but i fount is interesing while i observed some scenarios. I am curious about these things and want to get my doubts cleared.Here are the some observations i could make out. 1. What is the sigmificance of a regular inner class which is abstract or an interface. 2. If i have a inner class ... |
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Hi I have one doubt regarding Inner class... This is different than the other topic though... Can I create an Inner Class for a INNER class?? what will happen if I create and what is the use of it??? I tried creating it and was able to create one, but I wish to know is there any real world scenario which ... |
I think the problem is that there are a lot of sources that define 'being reachable' as 'there is somewhere a reference variable that points to this object'. And this is the way I always thought of it. And since there may be no direct reference variable pointing to outer class within the inner class, according to such definition it could ... |
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Hai all, I wrote one class and within that I wrote a inner class. If I make some of the variable in the inner class static the compiler is complaing that inner class should not contain static member. I am not able to understand why it should not be like that. Is there any body who can explain what is the ... |
The same as the difference between a private and a protected member variable: The acces to it. If you declare an inner class to be private, the only methods that can acces methods within that class are methods of the class encapseling that class. If you use protected, subclasses of the encapusing class may access it. /Mike |
Hi! I tried that link and may have found a mistake in to first part. This part: You can also instantiate both the outer class and inner class at the same time: Inner i = new Outer().new Inner(); Shouldn't that be: Outer.Inner g = new Outer().new Inner(); I did that and it worked for me. I'm just now learning about Inner ... |
- I'm using jdk 1.1.8 to present a dialog for an user name and password, and using anonymous inner classes to handle the AWT events on the dialog. There are three of them, one for the password text field and one each for the "Ok" and "Cancel" buttons. These three anonymous inner classes generate the expected Entrust$< nbr>.class files, one for ... |
Thanks Nathan. So, all inner classes (other than top-level static nested inner classes) cannot have static members other than primitive or String constants. Is that correct? Cindy...the link above was very entertaining.. Thanks. Why can't non-static inner classes have static members? Top-level classes have 'em. Qoute from the campfire story: "Another warning about all inner classes is that they can't declare ... |
public class A { private int m_PI = 3.14 ; public class B // inner class { private int ic_Count = 0 ; } public int GetPI() { return m_PI ; ic_Count++ ; } } Silly example but hopefully you get the idea. No one else has access to the inner class. And if the inner class was actually a robust ... |
The main difference between static and non-static inner class is that in the first case, you need to have a reference to the outer class if you want to handle the inner class (in case it is public). Public static inner classes are of interest if you want for example to add a unit testing code to you class. ... |
I'd agree with Cindy, also. I use them anytime that a class has a need, not just with Swing. Quick arbitrary example, Fruit and Seed. Since all fruits contain seeds, and seeds come from fruits, it makes sense to put Seed as an inner class of Fruit. You wouldn't make seed it's own class because you would never be able to ... |
Hello, I was just wondering if someone can help me understand inner classes a little. If I have the following code: Class Parent { private String myString = new String(I am parent); public void writeIt() { System.out.println(myString); } public void displayIt() { System.out.println((new InnerParent()).readMyString()); } class InnerParent { public String readMyString() { return myString; } } } class Child extends ... |
Just like you can access a static variable with the class name or with an instance of the class, you can access a static nested class with an instance of the outer class or with the outer class name. No error here. "Can an anonymous class access the member variables and methods of the outer class?" Yes. |