Afaik, in java instance variable and class variable are given default value based on it's type. False for boolean , 0 for byte and etc. Local variable (variable inside method) are slighty different , you must supply an initial value for them, if not, the compiler will gives you a compile-time error if you try to access uninitialized local variable.
Regards, Seeraz -----Original Message----- From: Nguyen Duc Khoi <[email protected]> Sender: [email protected] Date: Fri, 24 Dec 2010 11:21:00 To: <[email protected]> Reply-To: [email protected] Cc: <[email protected]> Subject: Re: [java programming] Variable declaration Hi Michel As i see in your comment > If no initial value is specified, Java supplies one (but it is not a good > practice to base the execution of your code on the default value). > So, if no initial value,is it be assigned a default value? I don't think so because if we implement a sample code int i; > System.out.print(i); > as expected, 0 value will be printed but we encounter an error. On Thu, Dec 23, 2010 at 1:11 PM, Mihai DINCA <[email protected]> wrote: > Hi Michel > > If no initial value is specified, Java supplies one (but it is not a good > practice to base the execution of your code on the default value). > > So, the code: > > ... > int i; > i = 32; > ... > > actually does: > > ... > int i = 0; > i = 32; > ... > > > If you are obsessed by performances, you might wish to write the above code > like this: > > ... > int i = 32; > ... > > > But the compiler probably does this optimization anyway. > > So, the thing that really matters is the clarity of your program. The code > must be enough explicit for you and anybody that reads it. What makes the > code easy to read is a matter of taste and experience (so the need to impose > standards when a whole team develop the same application). > > For e.g., your code : > > 1 import javax.swing.JOptionPane; > 2 > 3 public class GetInputFromKeyboard { > 4 > 5 public static void main( String[] args ){ > 6 String name = ""; > 7 name=JOptionPane.showInputDialog(“Please enter your name"); > 8 String msg = "Hello " + name + "!"; > 9 JOptionPane.showMessageDialog(null, msg); > 10 } > > can be written also like this: > > 1 import javax.swing.JOptionPane; > 2 > 3 public class GetInputFromKeyboard { > 4 > 5 public static void main( String[] args ){ > 6 JOptionPane.showMessageDialog( null, > 7 "Hello " + JOptionPane.showInputDialog( > 8 "Please enter your name"); > 9 } > > but for "didactic" purposes, it was put in the first form. > > Hope it helps > Mihai > > > Le 23/12/2010 00:23, Michel a écrit : > > Questions 1 > What is the difference between the following 2 declaration statements? > > char option; > option = 'C'; > > and > > char option='C'; > > > Questions 2 > Why sometimes we initialize variables and sometimes we don’t? > For example in the following program, we initialized the string name, > but we did not initialize the string msg: > > 1 import javax.swing.JOptionPane; > 2 > 3 public class GetInputFromKeyboard { > 4 > 5 public static void main( String[] args ){ > 6 String name = ""; > 7 name=JOptionPane.showInputDialog(“Please enter your name"); > 8 String msg = "Hello " + name + "!"; > 9 JOptionPane.showMessageDialog(null, msg); > 10 } > > > -- > To post to this group, send email to > [email protected] > To unsubscribe from this group, send email to > [email protected]<javaprogrammingwithpassion%[email protected]> > For more options, visit this group at > http://groups.google.com/group/javaprogrammingwithpassion?hl=en > -- Thanks, best regard! ====================================== Nguyen Duc Khoi Portal Team eXo Platform South East Asia (http://www.exoplatform.com) T: http://twitter.com/ndkhoiits F: http://facebook.com/ndkhoiits -- To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/javaprogrammingwithpassion?hl=en -- To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/javaprogrammingwithpassion?hl=en
