anonymous-inner-class

问题 I have encountered the following Java syntax that I don't recognize. This part is fine: public abstract class Stream<T> implements Iterator<T> { public boolean hasNext() { return true; } public void remove() { throw new RuntimeException("Unsupported Operation"); } } But this I don't get: Stream<Integer> ones = new Stream<Integer>() { public Integer next() { return 1; } }; while(true){ System.out.print(ones.next() + ", "); } What it is? 回答1: This is providing an inline (anonymous) subclass of

问题 I have encountered the following Java syntax that I don't recognize. This part is fine: public abstract class Stream<T> implements Iterator<T> { public boolean hasNext() { return true; } public void remove() { throw new RuntimeException("Unsupported Operation"); } } But this I don't get: Stream<Integer> ones = new Stream<Integer>() { public Integer next() { return 1; } }; while(true){ System.out.print(ones.next() + ", "); } What it is? 回答1: This is providing an inline (anonymous) subclass of

问题 I'm used to Swing and am exploring javafx. In swing I'd create a class that extends Jpanel and then be able to test that class with a couple of lines of code in that class that created a JFrame. So in javafx I thought I could just extend Scene or Group, and then be able to create an anonymous Application class in main but that fails with: Exception in thread "main" java.lang.RuntimeException: Error: class test.Test is not a subclass of javafx.application.Application at javafx.application

问题 I'm used to Swing and am exploring javafx. In swing I'd create a class that extends Jpanel and then be able to test that class with a couple of lines of code in that class that created a JFrame. So in javafx I thought I could just extend Scene or Group, and then be able to create an anonymous Application class in main but that fails with: Exception in thread "main" java.lang.RuntimeException: Error: class test.Test is not a subclass of javafx.application.Application at javafx.application

问题 I think I understand the basics of Anonymous classes but I'd like to clarify something. when I have a syntax such as this class A { class AnonymousClass1 Implements ActionListener{} } class A { public A() { JButton btn = new JButton(); btn.addActionListener( new ActionListener(){} ); } } If the anonymous class is actually an inner class of class A, as in the first example: in theory, is the semantics right? What happens exactly? I think when the java file is compiled, a .class file is created

问题 This question already has answers here : Why getClass returns the name of the class + $1 (or $*) (3 answers) Closed 6 years ago . Class A{ public void test(){ B b = new B(); System.out.println( "Class Name: " + b.createClassC().getClass() ); } } Class B{ public C createClassC(){ C c = new C(){ @Override public boolean equals( Object other ){ return true; } }; } } Class C{ int val = 8; } Output: Class Name: package.name.here .B Can some one tell me why anonymous class types gives the enclosing

问题 I have a method: void someMethod(String someString) final String[] testAgainst = {...}; .... for(int i = 0; i < testAgainst.length; i++) { if (someString.equals(testAgainst[i])) { AlertDialog.Builder builder = new AlertDialog.Builder(this); builder.setMessage("Strings are the same! Overwrite?") .setTitle("Blah Blah Blah") .setCancelable(false) .setPositiveButton("Overwrite", new DialogInterface.OnClickListener() { public void onClick(DialogInterface di, int which) { someAction() } })

问题 When shifting through java call graph generated by libraries like DependencyFinder and java-callgraph, I found out that java compiler generate names for anonymous functions, inner classes, etc. I've found out the meaning of a couple of them (please correct if I'm wrong): org.example.Bar$Foo refers to Foo , which is an inner class of org.example.Bar . org.example.Bar$1 refers to an anonymous class declared inside one of the methods of org.example.Bar . org.example.Bar.lambda$spam$1() refers to

问题 Assume that A is a custom class, and consider the following declaration of an anonymous inner class: A Obj = new A() { @Override public String toString() { return "Hello!"; } } In this scenario, Obj is an instance of an anonymous inner class whose toString method has been overridden. Since it was declared with type A, the anonymous class must be a subclass of A. So then, why isn't this class called an Anonymous Subclass instead of an anonymous inner class? Where does the 'inner' come from?

问题 What is happening while instantiating class Person? What is an anonymous inner class? abstract class Person { abstract void eat(); } class TestAnonymousInner { public static void main(String args[]) { Person p = new Person() { void eat() { System.out.println("nice fruits"); } // what happens here? }; p.eat(); } } 回答1: Anonymous classes are really just syntactic sugar. Since Person is abstract, you can't directly create an instance of Person . You must create an instance of a class that