在Java Swing上获取已更改的JTextField的值

Question

Hey guyz i'm working on a GPA calculator for my java assignment, and the gui i have created is 100% based on Events ie no buttons for the user to submit his data. my question is how do i know if a textfield value has changed and if it did how do i get the original value befor the change. another question how can i store each component in an arrayList do the user can create as many rows as they like Thanks this is the snapshot of mu GUI enter image description here BTW feel free any other suggestion

Answer 1

You can use keylistener

    JTextField usernameTextField= newJTextField(); 
usernameTextField.addKeyListener(new () { public void keyReleased(Key KeyAdapter Event e) { JTextField textField = (JTextField) e.getSource(); String text = textField.getText(); textField.setText(text.toUpperCase()); } public void keyTyped(KeyEvent e) { } public void keyPressed(KeyEvent e) { } });