variable declaration

[aravind kanna]

Even though java automatically assigns value for varialbles why Error occurs if the variables are printed without initialised?

[Jessica Sant]

I'm moving this to the Java In General (Beginner) forum.

I think what you're asking is this:

Even though java automatically assigns value for varialbles, why [does an] error occurs if the variables are printed without [first being] initialised?

.......................

Variables are given a default value if they are declared at a class level, but they are not assigned a value if they are declared locally (within a method). So you will receive an error if you try to use (for example, print) a local variable that you did not specifically assign a value to.


Check out this example to see what I'm talking about

public class assignValue{
    static int defaultAssignment;   // will automatically be initialized to 0
    static int explicitAssignment = 4;
 
    public static void main(String[] args )
    {
        int localExplicitAssignment = 10;
        int localDefaultAssignment;  // will not be given an initial value
 
        System.out.println( "default class level: " + defaultAssignment );
        System.out.println( "explicit class level: " + explicitAssignment );
        System.out.println( "explicit local level: " + localExplicitAssignment );
        // This line will give an error at compile time because the 
        // variable was not initialized.
        //System.out.println( "default local level: " + localDefaultAssignment );
    }
}

[ January 06, 2005: Message edited by: Jessica Sant ]

[Ernest Friedman-Hill]

Java automatically initializes member variables, but not local variables; i.e.,

class Example {
  int x; // Automatically initialized to 0
  Example() {
    int y; // NOT automatically initialized
    System.out.println(x); // OK
    System.out.println(y); // Error!
  }
}