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  1. /* package whatever; // don't place package name! */
  2.  
  3.  
  4. import sun.misc.Unsafe;
  5. import java.lang.reflect.Field;
  6.  
  7. /* Name of the class has to be "Main" only if the class is public. */
  8. class Ideone
  9. {
  10.  
  11. 	private static final Unsafe theUnsafe; 
  12. 	static {
  13. 		try {
  14. 			Field f = Unsafe.class.getDeclaredField("theUnsafe");
  15. 			f.setAccessible(true);
  16. 			theUnsafe = (Unsafe) f.get(null);
  17. 		} catch (ReflectiveOperationException roe) {
  18. 			throw new ExceptionInInitializerError(roe);
  19. 		}
  20. 	}
  21.  
  22. 	public static void setStaticObjectUnsafe(final Field field, Object value) {
  23.         final Object staticFieldBase = theUnsafe.staticFieldBase(field);
  24.         final long staticFieldOffset = theUnsafe.staticFieldOffset(field);
  25.         theUnsafe.putObject(staticFieldBase, staticFieldOffset, value);
  26.     }
  27.  
  28.     // Integer, not int, so javac won't inline it.
  29.     static final Integer VALUE = 10;
  30.  
  31.     static Integer useField() {
  32.         for (int i = 0; i < 1_000_000; i++) {
  33.             if (VALUE != 10) {
  34.                 return VALUE;
  35.             }
  36.         }
  37.         return VALUE;
  38.     }
  39.  
  40. 	public static void main (String[] args) throws Exception
  41. 	{
  42. 		useField();
  43. 		useField();
  44. 		setStaticObjectUnsafe(Ideone.class.getDeclaredField("VALUE"), 100);
  45. 		System.out.println(useField());
  46. 	}
  47. }
Success #stdin #stdout 0.1s 51832KB
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10
https://ideone.com/3Xv5Jo
language:
Java (HotSpot 12)
created:
2 years ago
visibility:
secret

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