java data types initializing

[thejaka samarakoon]

I have a problem in when primitive data types initialized.

  
public class Compare { 
   public static void main(String args[]) {
      int x = 10, y;
      if(x < 10) 
         y = 1;
      if(x>= 10) y = 2;
      System.out.println("y is " + y);
   }
}
  

this will give the output or error as the variable y is getting read before being properly initialized.but in this below code the variables got initialized to 0,what is the difference here.can anyone explain?

class example {
   int x;
   int y;
   String name;
   public static void main(String args[]) {
      example pnt = new example();
      System.out.println("pnt is " + pnt.name + 
         " " + pnt.x + " " + pnt.y);		
   }
}    

[Ankit Garg]

Local variables (variables declared inside methods) are not automatically initialized. Fields declared at class level are automatically initialized to the default value of their datatype...

[Sridhar Gudipalli]

This may help!!

[Abimaran Kugathasan]

  
public class Compare { 
   public static void main(String args[]) {
      int x = 10, y;
      if(x < 10) 
         y = 1;
      if(x>= 10) y = 2;
      System.out.println("y is " + y);// The compiler thinks, there are ways y isn't initialized
   }
}

The local variable should be initialized before they are used. The compiler will evaluate this value in all possible ways, that it thinks. And since we know that, in the above code, you initialized the variable y in all logically possible way with a poor if conditions, that's way it flags Compilation Error, saying that the variable y may not be initialized, if you change the as follows, you won't get Compilation Error. because you initialized the variable y in all the possible ways, that it thinks!

public class Compare {
   public static void main(String args[]) {
      int x = 10, y;
      if(x < 10)
         y = 1;
     	else y = 2;
      System.out.println("y is " + y);// No way to come here without going through the if - else block!
   }
}

[Mahmoud Hossam]

the compiler can't know for sure if the If-statements are going to execute,so it thinks that y is uninitialized