JAVA method of the class , any object can be modified ?

Thread thread = new Thread()
          {
              public void run()
              {
                  while(true)
                  {
                      try
                      {
                          Thread.sleep(500);
                      }
                      catch(Exception e){}
                      
                      System.out.println("1:"+this.getName());
                      System.out.println("2:"+Thread.currentThread().getName());
                  }
              }
          };

this problem a long time ago had thought at first to see the definition of an interface , you need to generate interface objects ( perhaps say there is an error generated interface objects , that is, new interfaces ) when the methods of the interface for the definition of the method body .
did feel very strange, because before seen a little bit of C + +, the impression that a class method is fixed, generally not in the definition of the object, and then the methods in the class to be modified. JAVA
but the interface is unique , think this is a new feature .

but just discovered this problem, which makes me very puzzled . The code is as above.
When I was in a class defines an object, I still can not abstract class non-abstract methods overridden .
that such classes and interfaces What's the difference , it is a more advanced interface ,

this class have the same thing only those properties and method names , as methods to complete the function , the programmer can define a class in its own object when modified.
( This is simply like an interface , rather than a class )

A few days ago saw a mention in the forum JAVA multi-state problem, I say without going through the JAVA virtual function , you can complete a subclass of the parent class method to access the operation . The results have a friend that , JAVA , in addition to final and static, all methods are virtual functions.
I did not know whether the object is generated rewrite the above methods.

There , JAVA in what time, the resulting object , you can not modify its corresponding class itself has been defined way to do that ?

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inheritance, anonymous inner classes
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there , JAVA in what time, the resulting object can not be modified which corresponds to the class itself has been defined way to do that ?
The final keyword can be used , and processing private access control , the method before adding final or private
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LZ, you want more, this is the anonymous class only, the final compilation , which is a class.
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interfaces, abstract classes , polymorphism , java features ah. . . .
When a thing can not or do not want to be another class called by another class called, you can use anonymous inner class friends.