In your case, the best way will be storing in .properties file.
And after getting a user input => store to the properties file.
Also, good practice for storing passwords in DB is to use one-way hash. A variety of hash methods is good for this: MD5, SHA-256, etc.
However, it works only for one way. More info here - MD5 algorithm Decryption in java.
And in your case properties file should be enough.
Example for db.properties:
db.username=MyUser db.password=MyPassword
You can have default values for connection. If user input doesn't match with it just print a warning message with something, like: "DB username or password is incorrect. Try again."
You can use something like JOptionPane for asking from user:
public void start() throws CreateDocumentConfigurationException { // Custom button text Object[] options = {"Yes, please", "Use default instead"}; int n = JOptionPane.showOptionDialog(null, "Would you like to enter DB credentials?", "DB Question", JOptionPane.YES_NO_CANCEL_OPTION, JOptionPane.QUESTION_MESSAGE, null, options, options[1]); estimateUserInput(n); // process result here. 0 - for entering new one, 1 - for using default }
