Containers and Components Graphical User Interfaces Frame OS managed container used to display GUI based java apps Panel Container used to organized other GUI components buttons labels etc Label Component used to display text Exercises Similar to Authority java from Lewis Loftus import java awt import javax swing public class GUI public static void main String args JFrame frame new JFrame First GUI takes title for window frame setDefaultCloseOperation JFrame EXIT ON CLOSE JPanel panel new JPanel panel setBackground Color red panel setPreferredSize new Dimension 250 75 JLabel label new JLabel My first GUI panel add label add label to panel frame getContentPane add panel add panel to content pane of frame frame pack size to the preferred size frame setVisible true make visible 1 Experiment with class GUI 1 2 3 4 5 Change the color of the panel Change the size of the panel See what happens if you do not pack See what happens if you do not make visible Add a second label of a different color public class GUIWButton More Components Buttons Component that can be pushed must invoke addActionListener in order to enable the program to respond to a button push program waits for an event and the performs the appropriate action public GUIWButton JFrame frame new JFrame First GUI frame setDefaultCloseOperation JFrame EXIT ON CLOSE JPanel panel new JPanel panel setBackground Color red panel setPreferredSize new Dimension 250 75 JLabel label new JLabel Count is 0 JButton button new JButton Push Me button addActionListener new ButtonListener label panel add label panel add button frame getContentPane add panel frame pack size to the preferred size frame setVisible true 1 private class ButtonListener implements ActionListener JLabel label int count public ButtonListener JLabel label this label label this count 0 public void actionPerformed ActionEvent event count label setText Count is count public static void main String args GUIWButton mygui new GUIWButton System out println running Exercises 1 Compile and run GUIWButton 2 Create a GUI with a label and text field Allow the user to enter text in the text field When the user presses enter update the text of the label to be the text contained in the text field 3 Add a button to the program you wrote for exercise 2 When the user presses the button OR presses enter update the text of the label to be the text contained in the text field 4 Modify your program from exercise 3 to keep a count of the number of times you have changed the label 2
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