public void init() {
    // 添加按钮
    JPanel buttonPanel = new JPanel();
    buttonPanel.add(okButton);

    mainPanel.setLayout(new GridLayout(0, 3));
    mainWin.add(mainPanel, BorderLayout.CENTER);

    JFormattedTextField intField0 =
        new JFormattedTextField(
            new InternationalFormatter(NumberFormat.getIntegerInstance()) {
              protected DocumentFilter getDocumentFilter() {
                return new NumberFilter();
              }
            });
    intField0.setValue(100);
    addRow("只接受数字的文本框", intField0);

    JFormattedTextField intField1 = new JFormattedTextField(NumberFormat.getIntegerInstance());
    intField1.setValue(new Integer(100));
    // 添加输入校验器
    intField1.setInputVerifier(new FormattedTextFieldVerifier());
    addRow("带输入校验器的文本框", intField1);

    // 创建自定义格式器对象
    IPAddressFormatter ipFormatter = new IPAddressFormatter();
    ipFormatter.setOverwriteMode(false);
    // 以自定义格式器对象创建格式化文本框
    JFormattedTextField ipField = new JFormattedTextField(ipFormatter);
    ipField.setValue(new byte[] {(byte) 192, (byte) 168, 4, 1});
    addRow("IP地址格式", ipField);

    mainWin.add(buttonPanel, BorderLayout.SOUTH);
    mainWin.pack();
    mainWin.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    mainWin.setVisible(true);
  }
  public static void main() {
    // Main
    frame = new JFrame("Java Playground");
    frame.setSize(640, 480);
    // Make sure the divider is properly resized
    frame.addComponentListener(
        new ComponentAdapter() {
          public void componentResized(ComponentEvent c) {
            splitter.setDividerLocation(.8);
          }
        });
    // Make sure the JVM is reset on close
    frame.addWindowListener(
        new WindowAdapter() {
          public void windowClosed(WindowEvent w) {
            new FrameAction().kill();
          }
        });

    // Setting up the keybinding
    // Ctrl+k or Cmd+k -> compile
    bind(KeyEvent.VK_K);

    // Ctrl+e or Cmd+e -> console
    bind(KeyEvent.VK_E);

    // Save, New file, Open file, Print.
    // Currently UNUSED until I figure out how normal java files and playground files will
    // interface.
    bind(KeyEvent.VK_S);
    bind(KeyEvent.VK_N);
    bind(KeyEvent.VK_O);
    bind(KeyEvent.VK_P);

    // Binds the keys to the action defined in the FrameAction class.
    frame.getRootPane().getActionMap().put("console", new FrameAction());

    // The main panel for typing code in.
    text = new JTextPane();
    textScroll = new JScrollPane(text);
    textScroll.setBorder(null);
    textScroll.setPreferredSize(new Dimension(640, 480));

    // Document with syntax highlighting. Currently unfinished.
    doc = text.getStyledDocument();
    doc.addDocumentListener(
        new DocumentListener() {
          public void changedUpdate(DocumentEvent d) {}

          public void insertUpdate(DocumentEvent d) {}

          public void removeUpdate(DocumentEvent d) {}
        });

    ((AbstractDocument) doc).setDocumentFilter(new NewLineFilter());

    // The output log; a combination compiler warning/error/runtime error/output log.
    outputText = new JTextPane();
    outputScroll = new JScrollPane(outputText);
    outputScroll.setBorder(null);

    // "Constant" for the error font
    error = new SimpleAttributeSet();
    error.addAttribute(StyleConstants.CharacterConstants.Italic, Boolean.TRUE);
    error.addAttribute(StyleConstants.Foreground, Color.RED);

    // "Constant" for the warning message font
    warning = new SimpleAttributeSet();
    warning.addAttribute(StyleConstants.CharacterConstants.Italic, Boolean.TRUE);
    warning.addAttribute(StyleConstants.Foreground, Color.PINK);

    // "Constant" for the debugger error font
    progErr = new SimpleAttributeSet();
    progErr.addAttribute(StyleConstants.Foreground, Color.BLUE);

    // Print streams to redirect System.out and System.err.
    out = new TextOutputStream(outputText, null);
    err = new TextOutputStream(outputText, error);
    System.setOut(new PrintStream(out));
    System.setErr(new PrintStream(err));

    // Sets up the output log
    outputText.setEditable(false);
    outputScroll.setVisible(true);

    // File input/output setup
    chooser = new JFileChooser();

    // Setting up miscellaneous stuff
    compiler = ToolProvider.getSystemJavaCompiler();
    JVMrunning = false;
    redirectErr = null;
    redirectOut = null;
    redirectIn = null;

    // Sets up the splitter pane and opens the program up
    splitter = new JSplitPane(JSplitPane.VERTICAL_SPLIT, textScroll, outputScroll);
    consoleDisplayed = false;
    splitter.remove(outputScroll); // Initially hides terminal until it is needed
    splitter.setOneTouchExpandable(true);
    frame.add(splitter);
    frame.setVisible(true);

    // Sets the divider to the proper one, for debugging
    // splitter.setDividerLocation(.8);
  }