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  1. import java.util.*;
  2. import java.lang.*;
  3. import java.io.*;
  4. import java.lang.reflect.ParameterizedType;
  5.  
  6. abstract class Mumble<T> {
  7. 	public abstract Mumble<Integer> getInstance();
  8.  
  9. 	protected T something;
  10.  
  11. 	@SuppressWarnings("unchecked")
  12. 	public Mumble<Integer> reflectInstance() throws Exception {
  13. 		Class<? extends Mumble> clazz = getClass();
  14. 		// Dirty implicit unchecked cast
  15. 		Mumble<Integer> obj = clazz.newInstance();
  16. 		obj.something = 20;
  17.  
  18. 		return obj;
  19. 	}
  20.  
  21. 	@SuppressWarnings("unchecked")
  22.     public void selfTest() throws Exception {
  23.     	 // Dirty
  24.          Mumble<Integer> obj =  (Mumble<Integer>) this;
  25.          System.out.println("this class = " + obj.getClass().getName()); 
  26.          // Mumble.something can hold any Object, this is why it is dirty
  27.          // something should be an Integer right? Wrong.
  28.          System.out.println("\tobj.something = " + obj.something);
  29.          obj = getInstance();
  30.          System.out.println("getInstance() class = " + obj.getClass().getName());
  31.          System.out.println("\tobj.something = " + obj.something);
  32.          obj = reflectInstance();
  33.          System.out.println("reflectInstance() class = " + obj.getClass().getName());
  34.          System.out.println("\tobj.something = " + obj.something);
  35.  
  36.     }
  37. } 
  38. class Bumble<T> extends Mumble<T> {
  39.     @Override
  40.     public Mumble<Integer> getInstance() {
  41.     	Bumble b = new Bumble<Integer>();
  42.     	b.something = 10;
  43.     	return b;
  44.     }
  45. }
  46.  
  47.  
  48. class Ideone{
  49. 	public static void main (String[] args) throws java.lang.Exception {
  50. 		Bumble<String> bumble = new Bumble<String>();
  51. 		bumble.something = "I'm a String";
  52. 		bumble.selfTest();
  53. 	}
  54. }
Success #stdin #stdout 0.07s 380224KB
comments (?)
stdin 
Standard input is empty
stdout 
this class = Bumble
	obj.something = I'm a String
getInstance() class = Bumble
	obj.something = 10
reflectInstance() class = Bumble
	obj.something = 20
https://ideone.com/ApXjds
http://stackoverflow.com/questions/21817728
language:
Java (12.0.1)
created:
10 years ago
visibility:
secret

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