Accessing constructor of an anonymous class

Lets say I have a concrete class Class1 and I am creating an anonymous class out of it.

Object a = new Class1(){
        void someNewMethod(){
        }
      };

Now is there any way I could overload the constructor of this anonymous class. Like shown below

Object a = new Class1(){
        void someNewMethod(){
        }
        public XXXXXXXX(int a){
          super();
          System.out.println(a);
        }
      };

With something at xxxxxxxx to name the constructor?

Solution 1:

From the Java Language Specification, section 15.9.5.1:

An anonymous class cannot have an explicitly declared constructor.

Sorry :(

EDIT: As an alternative, you can create some final local variables, and/or include an instance initializer in the anonymous class. For example:

public class Test {
    public static void main(String[] args) throws Exception {
        final int fakeConstructorArg = 10;

        Object a = new Object() {
            {
                System.out.println("arg = " + fakeConstructorArg);
            }
        };
    }
}

It's grotty, but it might just help you. Alternatively, use a proper nested class :)

Solution 2:

That is not possible, but you can add an anonymous initializer like this:

final int anInt = ...;
Object a = new Class1()
{
  {
    System.out.println(anInt);
  }

  void someNewMethod() {
  }
};

Don't forget final on declarations of local variables or parameters used by the anonymous class, as i did it for anInt.

Solution 3:

Here's another way around the problem:

public class Test{

    public static final void main(String...args){

        new Thread(){

            private String message = null;

            Thread initialise(String message){

                this.message = message;
                return this;
            }

            public void run(){
                System.out.println(message);
            }
        }.initialise(args[0]).start();
    }
}