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  1. /* package whatever; // don't place package name! */
  2.  
  3. import java.util.*;
  4. import java.lang.reflect.*;
  5. import java.io.*;
  6.  
  7. /* Name of the class has to be "Main" only if the class is public. */
  8. class Ideone
  9. {
  10.   public abstract static class ArrayListGeneric1<T> {
  11.     private int capacity = 1;
  12.     private int size = 0;
  13.     T[] array = (T[]) Array.newInstance(getElementType(), capacity);
  14.  
  15.     public ArrayListGeneric1() {}   
  16.  
  17.     Class<?> getElementType() {
  18.       ParameterizedType pt = (ParameterizedType) getClass().getGenericSuperclass();
  19.       Type[] typeArgs = pt.getActualTypeArguments();
  20.  
  21.       // Will fail if it's not a class type.
  22.       return (Class<?>) typeArgs[0];
  23.     }
  24. }
  25.  
  26. 	public static void main (String[] args) throws java.lang.Exception
  27. 	{
  28. 		System.out.println(new ArrayListGeneric1<String[]>() {}.array.getClass());
  29.         System.out.println(new ArrayListGeneric1<Integer>() {}.array.getClass());
  30. 	}
  31.  
  32. }
Success #stdin #stdout 0.09s 32992KB
comments (?)
stdin 
Standard input is empty
stdout 
class [[Ljava.lang.String;
class [Ljava.lang.Integer;
https://ideone.com/fgJ5dl
language:
Java (HotSpot 12)
created:
6 years ago
visibility:
public

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