FAQ - Traps

[vidhya Ramachandran]

Can somebody give an eg for the following:
1.Forward references to variables gives compiler error.
2.Instance initializer(s) gets executed ONLY IF the objects are constructed.

[Paul Anilprem]

public class TestClass
{
 static{ System.out.println(" in static block"); }
 { System.out.println(" in non static block"); }
 public static void main(String args[])
 {
  // i = 10; //will give compile time error.
  // int i;
  //new TestClass(); //"in non-static block" will not be printed.
 }
}
HTH,
Paul.

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[Mapraputa Is]

1.Forward references to variables gives compiler error.
Paul gave an example.
To be nit-picky and confuse you more, I'll give an example when they do not give compiler error.

class TestClass
{      int i = staticVar;
       static int staticVar = 10;
       public static void main(String args[]) 
       {    TestClass myTest = new TestClass();
            System.out.println (myTest.i);   // prints 10
       }
}

this code compiles because static vars are initizlized before instance vars, so forward reference instanceVar = staticVar is legal.