Access fo Method parameters to Anonymous Class ?

Can somebody please provide some more information on the statement below? I am also searching for some sample code implementations of it. It would help the cause better.
+"Methods of the object of the anonymous class need access to final local variables and method parameters belonging to the method in which the anonymous class is defined. "+
Thanks in Advance

We're concerned here with "local" classes, i.e. classes defined inside methods (not all anonymous classes are local, and not all local classes are anonymous).
The thing about local classes is that, unlike local variables etc., instances of a local class may survive the method returning. For example a local class might be a listener which gets added to a swing component, it could be a Runnable that get's launched as a thread.
Local classes get to access local variables and parameters of the method in which they are declared but the variables or parameters have to be declared final because, since the class needs to be able to access the value of the local variable even after the method exits, and the variable ceases to exist, what actually happens it that the value of the variable is copied into a special field of the anonymous class, and if the variable could be changed after the class was defined, the two copies would then disagree.

Similar Messages

  • Access DataControls methods in a java class

    Hi All,
    Jdeveloper Version 11.1.5
    I have created DataControls for SessionFacade web service.
    Inside the datacontrol there is a method getAllDepartments() which have a Return type which includes DaertmentId,DepartmentName,....
    I want to know how can i access this method inside a Java Class and create a list of only departmentId.

    You would need to add the method in the data control as a method action in your pageDef.
    After that, you could access the method as mentioned above.
    Thanks,
    Navaneeth

  • How to access private method of an inner class using reflection.

    Can somebody tell me that how can i access private method of an inner class using reflection.
    There is a scenario like
    class A
    class B
    private fun() {
    now i want to use method fun() of an inner class inside third class i.e "class c".
    Can i use reflection in someway to access this private method fun() in class c.

    I suppose for unit tests, there could be cases when you need to access private methods that you don't want your real code to access.
    Reflection with inner classes can be tricky. I tried getting the constructor, but it kept failing until I saw that even though the default constructor is a no-arg, for inner classes that aren't static, apparently the constructor for the inner class itself takes an instance of the outer class as a param.
    So here's what it looks like:
            //list of inner classes, if any
            Class[] classlist = A.class.getDeclaredClasses();
            A outer = new A();
            try {
                for (int i =0; i < classlist.length; i++){
                    if (! classlist.getSimpleName().equals("B")){
    //skip other classes
    continue;
    //this is what I mention above.
    Constructor constr = classlist[i].getDeclaredConstructor(A.class);
    constr.setAccessible(true);
    Object inner = constr.newInstance(outer);
    Method meth = classlist[i].getDeclaredMethod("testMethod");
    meth.setAccessible(true);
    //the actual method call
    meth.invoke(inner);
    } catch (Exception e) {
    throw new RuntimeException(e);
    Good luck, and if you find yourself relying on this too much, it might mean a code redesign.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               

  • Can we chagne Super class method parameters in Sub class

    Hi,
    I created a super class.  In that class i created a method. That method is having 4 input parameters and 4 export parameters.
    I created a sub class for that super class. I need to use only 2 input parameters in this class rather than 4 parameters. I want to delete 2 Input parameters in the sub class of the super class method.  Is it possible.
    If possible. can we give an simple code or pseudo code?
    regards,
    krishna

    Hi,
    I think you can not.
    Because, only public attributes can be inherited and they will remain public in the subclass.
    for further detail check,
    http://help.sap.com/saphelp_nw70/helpdata/en/1d/df5f57127111d3b9390000e8353423/content.htm
    regards,
    Anirban

  • Getting cl_abap_structdescr for method parameters of LOCAL classes?

    Hi guys
    I have a bit of a of a problem with getting an instance of the cl_abap_structdescr class for a method parameter type of a local class. The RTTI structure abap_parmdescr can only be used to diffrentiate between the basic built-in ABAP types and whether types are structures, tables or references. The question now arrives that once you have diffentiated that the parameter is a structure how do you determine the actual structure TYPE name for local classes to create an instance of the cl_abap_structdescr to continue your run-time analysis. For dictionary classes the parameter type name can be retrieved from the seosubcodf table, to me it looks as if one would have to resort to scanning the source code of local classes to arrive at the actual  structure type name, but before I go to THAT kind of trouble I was wondering whether somebody out there might have a better solution for me. Your help would be grreatly appreciated and rewarded ;).
    Kind regards
    Ettienne Hugo

    Hello Uwe
    Thanks for your reply, I checked out the CL_OO_LOCAL_CLASSES class, unfortunately the class actually operates on the local classes declared for a dictionary class. I think to clarify my question I should point out that the parameters I'm trying to process are parameters that belong to classes that are defined and implemented using include programs, these include programs would then typically be used in Function Groups to construct applications so the classes that I refer to are actually not in any way related to dictionary classes. The cl_abap_classdescr class works fine on these types of classes when you refer to them using the "\PROGRAM=my_program\CLASS=my_class" format with the describe_by_name method, unfortunately the class just does not provide sufficient information for structure type parameters to actually construct them during run-time...
    Stay well
    Ettienne

  • Access overriden method of an abstract class

    class Abstract
    abstract void abstractMethod(); //Abstract Method
    void get()
    System.out.print("Hello");
    class Subclass extends Abstract
    void abstractMethod()
    System.out.print("Abstract Method implementation");
    void get()
    System.out.print("Hiiii");
    In the above code, i have an abstract class called "Abstract", which has an abstract method named "abstractMethod()" and another method called "get()".
    Now, this class is extended by "Subclass", it provides implementation for "abstractMethod()", and also overrides the "get()" method.
    Now my problem is that i want to access the "get()" method of "Abstract" class. Since it is an abstract class, i cant create an object of it directly, and if i create an object like this:
    Abstract obj = new Subclass();
    then, obj.get() will call the get() method of Subclass, but how do i call the get() method of Abstract class.
    Thanks in advance

    hey thanks a lot,, i have another doubt regarding Abstract classes.
    i was just trying something, in the process, i noticed that i created an abstract class which does not have any abstract method, it gave no compilation errors. was wondering how come this is possible, and what purpose does it solve?

  • Accessing a method from an outside Class

    I am working on a program that will create an array list and hashmap of 3 shapes--squares,triangles and circles. I have created classes for each shape as well as a class that creates arrays of these shapes (called ShapeGenerator).
    Now I need to create a class that will call ShapeGenerator to create the shapes and then put them into an arraylist and hashmap. Right now I just can't get seem to call the methods from ShapeGenerator to create the arrays. What follows is the code I've written. Any guidance would be appreciated. Thanks in advance...
    public class ShapeMaker{
         public ShapeMaker(){
    public ShapeGenerator[] makeShapes(){
         ShapeGenerator[] myShapeGenerator = new ShapeGenerator();
         myShapeGenerator.createSquares(5);
         return createSquares;
    public static void main(String[] args){
         ShapeMaker mySM = new ShapeMaker();
         mySM.makeShapes();
         System.out.println("I made a Shape");
    }

    ShapeGenerator[] myShapeGenerator = new ShapeGenerator();
    new ShapeGenerator will return a single instance of ShapeGenerator - Not an array.
    to create a new ShapeGenerator:
    ShapeGenerator sg=new ShapeGenerator();
    then your method call:
    Object squares[]= sg.createSquares(5);
    or you could just do:
    Object squares[]=new ShapeGenerator().createSquares(5);
    makeShapes() should then return an array of Object (or even better do you have a base Shape class?)
    So we finally end up with something like:
    public class ShapeMaker{
    public ShapeMaker(){
    public Object[] makeShapes(){
    ShapeGenerator myShapeGenerator = new ShapeGenerator();
    return myShapeGenerator.createSquares(5);
    public static void main(String[] args){
    ShapeMaker mySM = new ShapeMaker();
    mySM.makeShapes();
    System.out.println("I made a Shape");
    Excuse any typos but I have not tried to compile this as I don't have a myShapeGenerator etc and I'm too tired (or lazy) to write one.
    Good luck.

  • Overloaded methods in a derived class

    Hello to everyone. I'm starting to learn java with the help of "Thinking in Java". I just want something to make it clearer for me.
    Suppose I have a base class with a method, and a derived class which overloads the method:
    class Base {
      void method() {
        System.out.println("Base method");
    class Derived extends Base {
      void method() {
        System.out.println("Derived method");
    }Now, in another class somewhere I create an instance of Derived:
    Derived dv = new Derived();
    dv.method();There is no way that I can access the method from the Base class, right? The only way I can do that is through
    class Derived extends Base {
      void method() {
        super();
        System.out.println("Derived method");
    }As I said, I'm almost sure that this is correct, I just want a confirmation.

    You can change the class
    class Derived extends Base {
      void method() {
        super.method();
        System.out.println("Derived method");
      // calls Base.method()
      void baseMethod() {
        super.method();
    }

  • Extending a class through inner anonymous class??

    What kind of construction is this?
    SomeClass sc = new SomeClass()
                      public void sayHello()
                        System.out.println("Hello");
              };I thought this is equal to sc extends SomeClass, and this is what the decompiled inner class tells. Anyhow I don't think this is the same as extending a class cause you can only overwrite methods which are declared/implemented in SomeClass, adding new methods doesn't make sense to compiler. If in the example above SomeClass doesn't contain sayHello method
    sc.sayHello();
    will result in compiler error message.

    The compiler error is because you are calling the method via a reference of type SomeClass, not a reference of the type of the anonyomous class you have created. If you need to do that, then use a named class.
    You can have any number of methods in an anonymous class, but you will only be able to call them from within the class itself unless they are declared in the superclass or super-interface.

  • Accessing a private variable from a public method of the same class

    can anyone please tell me how to access a private variable, declared in a private method from a public method of the same class?
    here is the code, i'm trying to get the variable int[][][] grids.
    public static int[][] generateS(boolean[][] constraints)
      private static int[][][] sudokuGrids()
        int[][][] grids; // array of arrays!
        grids = new int[][][]
        {

    Are you sure that you want to have everything static here? You're possibly throwing away all the object-oriented goodness that java has to offer.
    Anyway, it seems to me that you can't get to that variable because it is buried within a method -- think scoping rules. I think that if you want to get at that variable your program design may be under the weather and may benefit from a significant refactoring in an OOP-manner.
    If you need more specific help, then ask away, but give us more information please about what you are trying to accomplish here and how you want to do this. Good luck.
    Pete
    Edited by: petes1234 on Nov 16, 2007 7:51 PM

  • How to access a method of a class which just known class name as String

    Hi,
    Now I have several class and I want to access the method of these class. But what I have is a String which contain the complete name of the class.
    For example, I have two class name class1and class2, there are method getValue in each class. Now I have a String containing one class name of these two class. I want to access the method and get the return value.
    How could I do?
    With Class.forName().newInstance I can get a Object. but it doesn't help to access and execute the method I want .
    Could anybody help me?
    Thanks

    Or, if Class1 and Class2 have a common parent class or interface (and they should if you're handling them the same way in the same codepath)...Class c = Class.forName("ClassName");
    Object o = c.newInstance(); // assumes there's a public no-arg constructor
    ParentClassOrInterface pcoi = (ParentClassOrInterface)o;
    Something result = pcoi.someMethod(); Or, if you're on 5.0, I think generics let you do it this way: Class<ParentClassOrInterface> c = Class.forName("ClassName");
    // or maybe
    Class<C extends ParentClassOrInterface> c = Class.forName("ClassName");
    ParentClassOrInterface pcoi = c.newInstance();
    Something result = pcoi.someMethod();

  • Trying to use super class's methods from an anonymous inner class

    Hi all,
    I have one class with some methods, and a second class which inherits from the first. The second class contains a method which starts up a thread, which is an anonymous inner class. Inside this inner class, I want to call a method from my first class. How can I do this?
    If I just call the method, it will use the second class's version of the method. However, if I use "super," it will try to find that method in the Thread class (it's own super class) and complain.
    Any suggestions?
    Code:
    public class TopClass
         public void doSomething(){
              // do something
    =============================
    public class LowerClass extends TopClass
         // overrides TopClass's doSomething.
         public void doSomething(){
              // do something
         public void testThread(){
              Thread t = new Thread(){
                   public void run(){
                        doSomething();               //fine
                        super.doSomething();          //WRONG: searches class Thread for doSomething...
              t.start();
    }

    Classes frequently call the un-overridden versions of methods from their superclasses. That's that the super keyword is for, if I'm not mistaken.You're not mistaken about the keyword, but you're not calling the superclass method from a subclass. Your anonymous inner class is not a subtype of TopLevel. It's a subtype of Thread.
    Here it is no different, except that I happen to be in a thread at the time.It's vastly different, since you're attempting to call the method from an unrelated class; i.e., Thread.
    I could also be in a button's action listener, for example. It seems natural to me that if I can do it in a method, I should be able to do it within an anonymous inner class which is inside a method.If you were in an button's action listener and needed to call a superclass' implementation of a method overridden in the button, I'd have the same questions about your design. It seems smelly to me.
    ~

  • Accessing method in an inner class

    I have a class, which has an Inner Class, which is an extension of AbstractTableModel. The extended TableModel class has a new method, so it looks something like this;
    public class TheOuterClass
        JTable aTable
        TableModel theTableModel
        public initTable
             theTableModel = new MyTableModel();
         public TableModel getModel()
             return theTableModel;
         private class MyTableModel extends AbstractTableModel
                public void myTableModelMethod()
    }So, the idea here is that I have a class that has a table referenced by 'aTable', which uses MyTableModel as the class for it's table model. I have only implemented the basics here. The class also has a method called getModel(), so from a reference to 'TheOuterClass', I can access the table model.
    Now, say I have a reference to TheOuterClass called toc, and I want to access my new method in the table model;
    toc.getModel().myTableModelMethod()The above won't work, because getModel() returns a type of TableModel.
    My question then is how do I cast this to the correct type, so I can access the method 'myTableMethod()'?
    Is for example, the following a legal possibility, because I cannot seem to make it work;
    (toc.getModel().getClass())(toc.getModel()).myTableMethod();The quick fix, I guess is to correct getModel in TheOuterClass, so it returns the correct type, but I am hoping to not do this. (This is part of a larger piece of code obviously, and TheOuterClass is in reality a bean, and I don't wnat to disturb anymore than I have to).
    Any suggestions / ideas would be gratefully appreciated

    You are of course both correct, the class is private, should have spotted that! Doh. Also correct in that this is 'not the most elegant design', but you know the way it is you have to work with what you are given.
    So, I changed the class to public....
    What I had hoped is that the following would work
    ((toc.getModel().getClass())(toc.getModel())).myTableMethod()get a reference to the table model
    (toc.getModel())cast it to the correct type (not sure if this is a valid way to cast??)
    ((toc.getModel().getClass())(toc.getModel()))then call the method.
    This does not compile, it complains about a missing ')', and I'm sure they are all there. My question here then is, Is this a valid way to cast, now that the inner class is public?
    As to why I want to do this, then some explanation is required;
    The table model holds a Vector with all the data in it, some which is not actually in the table (it was originally written this way). My additional method myTableMethod() is intended to help access the data that is not shown in the table.
    Coming back to kajbj's point of creating an interface, I presume what is being suggested is that I create a public interface with the myTableMethod() in it, and make myTableModel implement this interface. Since the interface is public, then I can cast to that. Is this what you meant?
    Thanks for your help so far

  • How to access class variables in anonymous class??.

    I have a boolean class level variable. Fom a button action , this boolean will set to true and then it used in anonymous class. In anonymous class, I am getting default value instead of true. Could u anyone help in this plzzz.

    first of all, you don't want parent because that is something that Containers use to remember their containment hierarchy. you are thinking of super which is also incorrect, because that has to do with inheritance.
    the problem here is a scoping problem. you generally would use final if you were accessing variables in an anonymous class that are in the local scope. in this case, you just need to create some test code and play with it. snip the code below and play with it. it shows both the given examples and some additional ways to change/display class variables.
    good luck, hackerx
    import javax.swing.*;
    import java.awt.event.*;
    public class Foo extends JPanel
         private boolean the_b = true;
         public static void main(String[] args)
              Foo f = new Foo();
              JFrame frame = new JFrame();
              frame.getContentPane().add(f);
              frame.pack();
              frame.show();
         public Foo()
              // get your button
              JButton b = new JButton("Not!");
              b.addActionListener(new ActionListener()
                   public void actionPerformed(ActionEvent ae)
                        // *** uncomment these to play around ***
                        // Foo.this.the_b = false; // this will work, but unnecessary
                        // the_b = false; // this works fine too
                        notFoo();
              this.add(b);
              // something to show the value that accesses a class variable
              // using an inner class instead of final nonsense
              DisplayThread t = new DisplayThread();
              t.start();
         private void notFoo()
              the_b = !the_b;
         class DisplayThread extends Thread
              public void run()
                   while(true)
                        System.err.println("boolean value: " + the_b);
                        try {
                        sleep(1000);
                        } catch(InterruptedException ie) {}
    }

  • Some generic anonymous class overriding methods compile, while others don't

    I have the following (stripped-down) code. The abstract class SessionHandler<T> is used by other code to define and run an operation that needs a session to something. This is best done in my code with anonymous classes, because of the shear number of operations defined. In the EntityOps<T> class, these work great. But, in the last class shown here, SomeClass, the anonymous class definition fails, though the semantics are almost identical. (List<T> vs.List<AnotherClass>) What am I doing wrong here? Or is this a bug in Java?
    Thanks, Tom
    public interface IEntityOps<T> {
        T get();
        List<t> getAll();
    public abstract class SessionHandler<T> {
        abstract T handle(Session session) throws Throwable;
        public final T perform() {
            ... calls handle(session) ...
    // These anonymous class definitions compile fine!
    public class EntityOps<T> implements IEntityOps<T> {
        public T get() {
            T ret = null;
            ret = new SessionHandler<T>() {
                T handle(Session s) throws Throwable {
                    T ret = (some T object calculation);
                    return ret;
            }.perform();
            return ret;
        public List<T> getAll() {
            T ret = null;
            return new SessionHandler<List<T>>() {
                List<T> handle(Session s) throws Throwable {
                    List<T> ret = (some List<T> calculation);
                    return ret;
            }.perform();
    // This anonymous class definition fails with the error:
    // "SomeClass.java": <anonymous someMethod> is not abstract and does not override abstract method handle()
    //     in SessionHandler at line XX, column XX
    public class SomeClass {
        public List<AnotherClass> someMethod() throws {
            List<AnotherClass> ret = null;
            ret = new SessionHandler<List<AnotherClass>>() {
                List<AnotherClass> handle(Session s) throws Throwable {
                    List<AnotherClass> ret = (some List<AnotherClass> calculation);
                    return ret;
            }.perform();
            return ret;
    }

    I added @Override above the abstract method override, and it provides this additional error:
    "HousingConfigImpl.java": method does not override a method from its superclass at line 382, column 17
    I have also reconstructed the code layout in a separate set of classes that have no dependancies, but there's no error coming from these!
    public class CustomThing {
    public interface ISomeInterface<T> {
        List<T> interfaceMethod();
    public abstract class SomeAbstractClass<T> {
        private Class _c = null;
        public SomeAbstractClass(Class c) {
            _c = c;
        protected Class getC() {
            return _c;
        public abstract T methodToOverride(Object neededObject) throws Throwable;
        public final T finalMethod() {
            try {
                return methodToOverride(new Object());
            } catch(Throwable e) {
                throw new RuntimeException(e);
    import java.util.List;
    import java.util.Collections;
    public class SomeInterfaceImpl<T> implements ISomeInterface<T> {
        public List<T> interfaceMethod() {
            return new SomeAbstractClass<List<T>>(CustomThing.class) {
                public List<T> methodToOverride(Object neededObject) throws Throwable {
                    return Collections.emptyList();
            }.finalMethod();
    import java.util.Collections;
    import java.util.List;
    public class SomeOtherClass {
        public List<CustomThing> someMethod() {
            return new SomeAbstractClass<List<CustomThing>>(CustomThing.class) {
                public List<CustomThing> methodToOverride(Object neededObject) throws Throwable {
                    return Collections.emptyList();
            }.finalMethod();
    }So, there's something about my code that causes it to be, somehow, different enough from the example provided above so that I get the error. The only differences in the override method definitions in my actual code are in the return type, but those are different in the example above as well. Here are the class declarations, anonymous abstract class creation statements, and abstract method declarations from the actual code.
    public abstract class SessionHandler<T> {
        abstract T handle(Session session) throws Throwable;
    public class EntityOps<T> implements IEntityOps<T> {
                return new SessionHandler<List<T>>(_mgr, _c, "getAll" + _c.getName()) {
                    List<T> handle(Session s) throws Throwable {
    public class HousingConfigImpl implements IHousingConfigOperations, ISessionFactoryManager {
                ret = new SessionHandler<List<Tenant>>((ISessionFactoryManager)this, Housing.class, "getTenantsInNeighborhood") {
                    List<Housing> handle(Session s) throws Throwable {I can't for the life of me see any syntactical difference between my example and the real code. But, one works and the other doesn't.

Maybe you are looking for