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Demo of MVC concepts using Java's Swing.
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| import javax.swing.*; | |
| import javax.swing.text.AttributeSet; | |
| import javax.swing.text.BadLocationException; | |
| import javax.swing.text.PlainDocument; | |
| import java.awt.*; | |
| import java.awt.event.WindowAdapter; | |
| import java.awt.event.WindowEvent; | |
| public class Swing_MVC_MultiCounterDemo extends JFrame { | |
| // See also two inner classes: CounterWidget & CounterModel | |
| final CounterModel model; | |
| public Swing_MVC_MultiCounterDemo() {{ | |
| setTitle("Counter MVC demo using Swing"); | |
| model = new CounterModel(0); | |
| add(new JPanel(){{ | |
| setBorder(BorderFactory.createTitledBorder("Single Shared Model")); | |
| add(new CounterWidget(model).view); | |
| add(new CounterWidget(model).view); | |
| setLayout(new BoxLayout(this, BoxLayout.Y_AXIS)); | |
| }}); | |
| add(new JPanel(){{ | |
| setBorder(BorderFactory.createTitledBorder("Two Separate Models")); | |
| add(new CounterWidget(new CounterModel(3)).view); | |
| add(new CounterWidget(new CounterModel(17)).view); | |
| setLayout(new BoxLayout(this, BoxLayout.Y_AXIS)); | |
| }}); | |
| getContentPane().setLayout(new BoxLayout(getContentPane(), BoxLayout.Y_AXIS)); | |
| pack(); | |
| setLocation(500, 500); | |
| }} | |
| public static void main(String[] args) { | |
| Swing_MVC_MultiCounterDemo demo = new Swing_MVC_MultiCounterDemo(); | |
| demo.addWindowListener(new WindowAdapter() | |
| { | |
| @Override | |
| public void windowClosing(WindowEvent e) | |
| { | |
| e.getWindow().dispose(); | |
| System.out.println("Frame closed, views/controllers eligible for GC, model value = " | |
| + demo.model.getCount() + ". Now exit."); ; | |
| } | |
| }); | |
| demo.setVisible(true); | |
| } | |
| public class CounterWidget { | |
| final View view; | |
| class View extends JPanel { | |
| final JTextField text; | |
| final JButton plus; | |
| final JButton minus; | |
| View(CounterModel model) {{ | |
| add(new JLabel("Count:")); | |
| text = new JTextField("0", 4); | |
| text.setDocument(model); | |
| add(text); | |
| plus = new JButton("+"); | |
| final int s = (int) (getFont().getSize() * 1.7); | |
| plus.setPreferredSize(new Dimension(s, s)); | |
| add(plus); | |
| minus = new JButton("-"); | |
| minus.setPreferredSize(new Dimension(s, s)); | |
| add(minus); | |
| }} | |
| } | |
| CounterWidget(CounterModel model) { | |
| view = new View(model); | |
| // controller logic | |
| view.plus.addActionListener(e -> { | |
| model.increment(); | |
| }); | |
| view.minus.addActionListener(e -> { | |
| model.decrement(); | |
| }); | |
| } | |
| } | |
| public class CounterModel extends PlainDocument { | |
| CounterModel(int initialValue) { | |
| setCount(initialValue); | |
| } | |
| void increment() { | |
| setCount(getCount() + 1); | |
| } | |
| void decrement() { | |
| setCount(getCount() - 1); | |
| } | |
| private void setCount(int i) { | |
| try { | |
| super.remove(0, getLength()); | |
| super.insertString(0, "" + i, null); | |
| } catch (BadLocationException e) { | |
| throw new UnsupportedOperationException(e); | |
| } | |
| } | |
| int getCount() { | |
| try { | |
| return Integer.parseInt(super.getText(0, super.getLength())); | |
| } catch (BadLocationException e) { | |
| throw new UnsupportedOperationException(e); | |
| } | |
| } | |
| public void insertString(int offset, String str, AttributeSet attr) throws BadLocationException { | |
| for (int i = 0; i < str.length(); i++) { | |
| final char c = str.charAt(i); | |
| if (!"0123456789".contains(String.valueOf(c))) | |
| if (i == 0 && c != '-') { | |
| return; | |
| } | |
| } | |
| super.insertString(offset, str, attr); | |
| } | |
| } | |
| } |
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That app, when running, looks like:
The first two counters move up and down together. The third and fourth two are independent of each other (as well as independent to the first two).