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Thread: Hello, why have an error? someone help me

  1. #1
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    Default Hello, why have an error? someone help me

    import java.awt.*;
    import java.awt.event.ActionEvent;
    import java.awt.event.ActionListener;
    import javax.swing.*;
    import javax.swing.border.*;

    public class Exercise16_10 extends JFrame implements ActionListener {
    // Declare a panel for displaying message

    private MessagePanel messagePanel;
    // Declare two buttons to move the message left and right
    private JButton jbtLeft, jbtRight;
    private JTextField jtfNewMessage = new JTextField(8);
    private JComboBox jcboInterval = new JComboBox();
    private JRadioButton jrbRed = new JRadioButton("Red");
    private JRadioButton jrbGreen = new JRadioButton("Green");
    private JRadioButton jrbBlue = new JRadioButton("Blue");
    private JCheckBox jchkCentered = new JCheckBox("Center");
    private JCheckBox jchkBold = new JCheckBox("Bold");
    private JCheckBox jchkItalic = new JCheckBox("Italic");
    // Font name
    private String fontName = "SansSerif";
    // Font style
    private int fontStyle = Font.PLAIN;
    // Font Size
    private int fontSize = 12;

    /** Main method */
    public static void main(String[] args) {
    Exercise16_10 frame = new Exercise16_10();
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOS E);
    frame.setSize(500, 200);
    frame.setVisible(true);
    }

    /** Default constructor */
    public Exercise16_10() {
    setTitle("Exercise16_10");

    // Create a MessagePanel instance and set colors
    /*messagePanel = new MessagePanel("Welcome to Java");
    messagePanel.setBackground(Color.white);*/

    // Create Panel jpButtons to hold two Buttons "<=" and "right =>"
    JPanel jpButtons = new JPanel();
    jpButtons.setLayout(new FlowLayout());
    jpButtons.add(jbtLeft = new JButton());
    jpButtons.add(jbtRight = new JButton());

    // Set button text
    jbtLeft.setText("<=");
    jbtRight.setText("=>");

    // Set keyboard mnemonics
    jbtLeft.setMnemonic('L'); // When a key is pressed on the keyboard,
    //only the menu item that has the mnemonic matching the pressed key will fire an action event.
    jbtRight.setMnemonic('R');

    // Set icons
    //jbtLeft.setIcon(new ImageIcon("image/left.gif"));
    //jbtRight.setIcon(new ImageIcon("image/right.gif"));

    // Set toolTipText on the "<=" and "=>" buttons
    jbtLeft.setToolTipText("Move message to left");
    jbtRight.setToolTipText("Move message to right");

    // Place panels in the frame
    getContentPane().setLayout(new BorderLayout());
    getContentPane().add(messagePanel, BorderLayout.CENTER);
    getContentPane().add(jpButtons, BorderLayout.SOUTH);

    // Register listeners with the buttons
    jbtLeft.addActionListener(this);
    jbtRight.addActionListener(this);

    /** 1.Add a text field labeled “New Message.\uFFFD
    * Upon typing a new message in the text field and pressing the Enter
    * key, the new message is displayed in the message panel.
    */
    jpButtons.add(new JLabel("Enter a new message"));
    jpButtons.add(jtfNewMessage);

    jtfNewMessage.addActionListener(this);

    /** 2. Add a combo box label “Interval\uFFFD that enables the user to select a
    * new interval for moving the message. The selection values range from
    * 10 to 100 with interval 5. The user can also type a new
    * interval in the combo box.
    */
    jpButtons.add(new JLabel("Select an interval"));
    jpButtons.add(jcboInterval);
    for (int interval = 5; interval <= 100; interval += 5) {
    jcboInterval.addItem(interval + "");
    }

    jcboInterval.addActionListener(this);

    /**
    * 3. Add three radio buttons that enable the user to select the foreground
    * color for the message as Red, Green, and Blue.
    */
    JPanel panel = new JPanel();
    getContentPane().add(panel, BorderLayout.NORTH);

    panel.add(jrbRed);
    panel.add(jrbGreen);
    panel.add(jrbBlue);
    ButtonGroup btg = new ButtonGroup();
    btg.add(jrbRed);
    btg.add(jrbGreen);
    btg.add(jrbBlue);
    jrbRed.addActionListener(this);
    jrbGreen.addActionListener(this);
    jrbBlue.addActionListener(this);

    /**
    * 4. Add three check boxes that enable the user to center the message
    * and display it in italic or bold.
    */
    panel.add(jchkCentered);
    panel.add(jchkBold);
    panel.add(jchkItalic);
    jchkCentered.addActionListener(this);
    jchkBold.addActionListener(this);
    jchkItalic.addActionListener(this);

    /**
    * 5. Add a border titled “Message Panel\uFFFD on the message panel.
    */
    //messagePanel.setBorder(new TitledBorder("Message Panel"));
    jpButtons.setBorder(new TitledBorder("South Panel"));
    panel.setBorder(new TitledBorder("North Panel"));

    this.setCursor(new Cursor(Cursor.CROSSHAIR_CURSOR));
    }

    /** Handle button events */
    public void actionPerformed(ActionEvent e) {
    if (e.getSource() == jbtLeft) {
    messagePanel.moveLeft();
    messagePanel.repaint();
    } else if (e.getSource() == jbtRight) {
    messagePanel.moveRight();
    messagePanel.repaint();
    } else if (e.getSource() == jtfNewMessage) {
    messagePanel.setMessage(jtfNewMessage.getText());
    messagePanel.repaint();
    } else if (e.getSource() == jcboInterval) {
    messagePanel.setInterval(
    Integer.parseInt((String) (jcboInterval.getSelectedItem())));
    messagePanel.repaint();
    } else if (e.getSource() == jrbRed) {
    messagePanel.setForeground(Color.red);
    } else if (e.getSource() == jrbGreen) {
    messagePanel.setForeground(Color.green);
    } else if (e.getSource() == jrbBlue) {
    messagePanel.setForeground(Color.blue);
    } else if (e.getSource() == jchkCentered) {
    if (jchkCentered.isSelected()) {
    messagePanel.setCentered(true);
    } else {
    messagePanel.setCentered(false);
    }

    messagePanel.repaint();
    } else if ((e.getSource() == jchkBold) ||
    (e.getSource() == jchkItalic)) {
    fontStyle = Font.PLAIN;

    // Determine a font style
    if (jchkBold.isSelected()) {
    fontStyle = fontStyle + Font.BOLD;
    }
    if (jchkItalic.isSelected()) {
    fontStyle = fontStyle + Font.ITALIC;
    }

    // Set font for the message
    messagePanel.setFont(new Font(fontName, fontStyle, fontSize));
    }
    }
    }


  2. #2
    Super Moderator Norm's Avatar
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    Default Re: Hello, why have an error? someone help me

    You forgot to copy and paste here the full text of the error message.

    Please edit your post and wrap your code with
    [code=java]
    <YOUR CODE HERE>
    [/code]
    to get highlighting and preserve formatting.
    If you don't understand my answer, don't ignore it, ask a question.

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