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  1. abstract class Super {
  2.     protected static Object staticVar;
  3.  
  4.     protected static void staticMethod() {
  5.         System.out.println( staticVar );
  6.     }
  7. }
  8.  
  9. class Sub extends Super {
  10.     static {
  11.     	System.out.println("init");
  12.         staticVar = new Object();
  13.     }
  14.  
  15.    /*
  16.    public static void someOtherMethod(){}
  17.    */
  18.  
  19.     /* Implementing a method with the same name here avoids staticVar being null
  20.     public static void staticMethod() {
  21.         Super.staticMethod();
  22.     }*/
  23.  
  24. }
  25.  
  26. class UsersClass {
  27.     public static void main( String[] args ) throws Exception {
  28.         Class.forName("Sub");
  29.         //Sub.someOtherMethod();
  30.         new UsersClass().method();
  31.     }
  32.  
  33.     void method() {
  34.         Sub.staticMethod(); // prints "null"
  35.     }
  36. }
Success #stdin #stdout 0.09s 380224KB
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stdin 
Standard input is empty
stdout 
init
java.lang.Object@8e2fb5
https://ideone.com/pUyVj4
language:
Java (HotSpot 12)
created:
10 years ago
visibility:
public

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