VariableExample -- declaring/using instance variables and class variables.
To see this example in action:
  1. Compile the Java source file, VariableExample.java: 
    	javac VariableExample.java
  2. Run the class: 
    	java VariableExample


Output: 
    After creating ex1 and ex2:
      ex1.classVar = null
      ex2.classVar = null
      ex1.instanceVar = null
      ex2.instanceVar = null

    After setting ex1.classVar and ex1.instanceVar:
      ex1.classVar = class variable set by ex1
      ex2.classVar = class variable set by ex1
      ex1.instanceVar = instance variable set by ex1
      ex2.instanceVar = null

    After setting ex2.classVar and ex2.instanceVar:
      ex1.classVar = class variable set by ex2
      ex2.classVar = class variable set by ex2
      ex1.instanceVar = instance variable set by ex1
      ex2.instanceVar = instance variable set by ex2

    ex1.instanceVar == ex2.instanceVar?  false
    ex1.classVar == ex2.classVar?  true
    ex1.classVar == VariableExample.classVar?  true
    ex2.classVar == VariableExample.classVar?  true
The source.