title: Can I call methods in constructor in Java?
body: <p>I have situation, where I want to read configuration file only one time, when class is instantiated.</p>
  
  <p>Suppose I have a method named <code>readConfig()</code>, that reads configuration and puts it into a <code>Map</code> object. When the program is required to use configuration value it reads object with it's define key. I want to know that constructor calls only once it's life cycle. Can I put my method <code>readConfig()</code> into constructor, which would give me benefit of one time calling or is there another mechanism to do that?</p>