I want to make a JTextField accept values only when "Enter" on keyboard is hit. That is if you type something and move the mouse away before hitting return, then it should put back the old value. How to force this behavior in jTetxtField? The purpose of this is that then I can do some verification of the text data entry.
1. Add a FocusListener to the JTextField. On focusGained you save the current value. On focusLost you reset the text field with the saved value.
2) Add an ActionListener to the text field. When the ActionEvent fires you get the current value and update the saved valued.
However this sounds like a strange requirement. Maybe you should be displaying a JOptionPane asking the user to enter a value. Then if the user hits OK on the option pane you save the value otherwise you ignore the value.