inner-classes

问题 Closed . This question is opinion-based. It is not currently accepting answers. Want to improve this question? Update the question so it can be answered with facts and citations by editing this post. Closed 3 years ago . 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 on version 5 and it has an example using an inner class, but I thought I read somewere that inner classes were "bad." I have

问题 I'm find I have several places that having public static inner classes designed that extend "helper" classes makes my code a lot more type safe and, in my opinion, readable. For example, imagine I have a "SearchCriteria" class. There are a lot of commonalities for the different things I search for (a search term and then a group of search term types, a date range, etc.) By extending it in a static inner class, I tightly couple the extension and the searchable class with the specific

问题 I'm find I have several places that having public static inner classes designed that extend "helper" classes makes my code a lot more type safe and, in my opinion, readable. For example, imagine I have a "SearchCriteria" class. There are a lot of commonalities for the different things I search for (a search term and then a group of search term types, a date range, etc.) By extending it in a static inner class, I tightly couple the extension and the searchable class with the specific

问题 In there an internal issue why java anonymous classes cannot implement and subclass at the same time? Or is it just because the syntax? 回答1: In there an internal issue why java anonymous classes cannot implement and subclass at the same time? I believe it is 99% due to syntactical reasons. Type parameters even support intersection types ( <T extends InterfaceX & InterfaceY> ) so I don't think such feature would introduce any contradictions or complications. An expression like new (InterfaceX

问题 Outer outer = new Outer(); an Object of Outer class is created on heap and reference variable points to it. If I understand it right when I write Outer.Inner inner=outer.new Inner(); an object of Inner class is created on heap and inner points to it. In heap we have two separate objects which contains their own instance variables. But if I write Outer.Inner inner=new Outer().new Inner(); still two Object would be created on heap one for Outer and other for Inner . But with reference the inner

问题 Im still new to java and i tried to create a inner class and call the method inside main. But theres a compilation error saying "Non static variable - This cannot be referenced from a static context" Please help class Class1{ public static void main(String args []){ Class2 myObject = new Class2(); myObject.newMethod(); } public class Class2{ public void newMethod(){ System.out.println("Second class"); } } } 回答1: An inner class needs a reference to an instance of the outer class in order to be

问题 I need to override a getFilter() method from the class ArrayAdapter and i found the source code from here in the github //package name import java.util.ArrayList; import java.util.Arrays; import java.util.List; import android.content.Context; import android.util.Log; import android.widget.ArrayAdapter; import android.widget.Filter; import android.widget.Filterable; public class CustomAdapter<T> extends ArrayAdapter<T> implements Filterable{ private ArrayList<T> mOriginalValues; private List<T

问题 The following code tries to mimic Polymorphic Embedding of DSLs: rather than giving the behavior in Inner , it is encoded in the useInner method of its enclosing class. I added the enclosing method so that user has only to keep a reference to Inner instances, but can always get their enclosing instance. By doing this, all Inner instances from a specific Outer instance are bound to only one behavior (but it is wanted here). abstract class Outer { sealed class Inner { def enclosing = Outer.this

问题 Say if I have a dropdown in a form and I have another nested class inside of this class . Now what's the best way to access this dropdown from the nested class? 回答1: Unlike Java, a nested class isn't a special "inner class" so you'd need to pass a reference. Raymond Chen has an example describing the differences here : C# nested classes are like C++ nested classes, not Java inner classes. Here is an example where the constructor of the nested class is passed the instance of the outer class

问题 I am working on a class with an inner class My code: package com.solignis; public class Config { public static final Target target; class Target { public void create(String targetName) { System.out.println("Created" + targetName); } public void destroy(String targetName) { System.out.println("Destroyed" + targetName); } } } IntelliJ doesn't see anything wrong with the subclass but it keeps complaining that I have not initalized the static variable target . But when I try to initialize it with