title: Why is it possible to declare a variable without an initial value?
body: <p>I'm reading Gilles Dowek's <em>Principles of Programming Languanges</em>:</p>
  
  <p>He says that it's also possible to declare a variable without giving it an initial value and also that we must be careful not to use a variable which has been declared without an initial value and that has not been assigned a value. This produces an error.</p>
  
  <p><strong>Note:</strong> The book's author mentions the possibility of declaring variables without an initial value on Java.</p>
  
  <p>So, why is this declaration of variables valid? When am I going to use it?</p>