Here are three complete tutorials on JTextField, JFormattedTextField and JPasswordField that you need to ace to be a better swing programmer.
JTextField
JTextField, as you know, is a component used to write a single line of text. A text field can be seen at this blog's side bar, the subscribe field, where you type your email address.
JPasswordField
JPasswordField is much similar to a JTextField but it allows user to type passwords rather than simple text. You know, your text is visible as it is when you type in your email id, but in the case of password, some round black filled circles are displayed which are used to mask your password, but what you type is the same. This class also gives the option to morph the text with the type of character you want, if you don't like that black spot.
JFormattedTextField
This is a different type of JTextField. This allows user to enter a particular type of data. For example, you can restrict the user to enter only date in it, or a number, or a decimal value ranging between 0.0 and 1.0 etc. Anything else that the user types, will not be accepted. You can better understand this, if you look at the example.