user1762031 user1762031 - 4 months ago 10
Java Question

What is the correct way to declare a boolean variable in Java?

I have just started learning Java. In the online course I am following, I am asked to try the following code:

String email1 = "meme@me.coh";
String email2 = "meme@me.com";
Boolean isMatch = false;

isMatch = email1.equals (email2);

if (isMatch == true){
System.out.println("Emails match");
}
else{
System.out.println("Emails don't match");
}


I don't understand why I'm asked to declare
isMatch
as false when on the next line i am comparing the email addresses and assigning the value to
isMatch
.

I've tried the following code which seems to work just the same:

String email1 = "meme@me.coh";
String email2 = "meme@me.com";
Boolean isMatch;

isMatch = email1.equals (email2);

if (isMatch == true){
System.out.println("Emails match");
}
else{
System.out.println("Emails don't match");
}


On the course it doesn't explain why I'm declaring
isMatch
as false first. Is there a reason why I must declare
isMatch
as false before comparing the email addresses?

Answer

You don't have to, but some people like to explicitly initialize all variables (I do too). Especially those who program in a variety of languages, it's just easier to have the rule of always initializing your variables rather than deciding case-by-case/language-by-language.

For instance Java has default values for Boolean, int etc .. C on the other hand doesn't automatically give initial values, whatever happens to be in memory is what you end up with unless you assign a value explicitly yourself.

In your case above, as you discovered, the code works just as well without the initialization, esp since the variable is set in the next line which makes it appear particularly redundant. Sometimes you can combine both of those lines (declaration and initialization - as shown in some of the other posts) and get the best of both approaches, i.e., initialize the your variable with the result of the email1.equals (email2); operation.

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