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Java图形用户界面(GUI)工具包swing来写一个简单的留言板程序（不带数据库）

package demo2;import java.awt.BorderLayout;import javax.swing.JPanel;import javax.swing.JFrame;import java.awt.Rectangle;import javax.swing.JLabel;import javax.swing.SwingConstants;import java.awt.Font;import javax.swing.JTextArea;import javax.swing.JScrollBar;import javax.swing.JScrollPane;import javax.swing.JComboBox;import javax.swing.JTextField;import javax.swing.JButton;import java.util.Date;public class jiang1 extends JFrame {
    private static final long serialVersionUID = 1L; private JPanel jContentPane = null; private JLabel jLabel = null; private JTextArea jTextArea = null; private JScrollPane jScrollPane = null; private JLabel jLabel1 = null; private JComboBox jComboBox = null; private JLabel jLabel2 = null; private JTextField jTextField = null; private JButton jButton = null; private JButton jButton1 = null; private JButton jButton2 = null; private JButton jButton3 = null; /**  * This is the default constructor  */ public jiang1() {  super();  initialize(); } /**  * This method initializes this  *   * @return void  */ private void initialize() {  this.setContentPane(getJContentPane());  this.setTitle("留言板程序");  this.setBounds(new Rectangle(0, 0, 640, 680));  this.setVisible(true); } /**  * This method initializes jContentPane  *   * @return javax.swing.JPanel  */ private JPanel getJContentPane() {  if (jContentPane == null) {   jLabel2 = new JLabel();   jLabel2.setBounds(new Rectangle(210, 407, 90, 24));   jLabel2.setFont(new Font("Dialog", Font.BOLD, 14));   jLabel2.setText("输入留言：");   jLabel1 = new JLabel();   jLabel1.setBounds(new Rectangle(40, 407, 90, 24));   jLabel1.setFont(new Font("Dialog", Font.BOLD, 14));   jLabel1.setText("选择角色：");   jLabel = new JLabel();   jLabel.setBounds(new Rectangle(283, 15, 45, 20));   jLabel.setHorizontalAlignment(SwingConstants.CENTER);   jLabel.setFont(new Font("Dialog", Font.BOLD, 14));   jLabel.setText("留言板");   jContentPane = new JPanel();   jContentPane.setLayout(null);   jContentPane.add(jLabel, null);   jContentPane.add(getJScrollPane(), null);   jContentPane.add(jLabel1, null);   jContentPane.add(getJComboBox(), null);   jContentPane.add(jLabel2, null);   jContentPane.add(getJTextField(), null);   jContentPane.add(getJButton(), null);   jContentPane.add(getJButton1(), null);   jContentPane.add(getJButton2(), null);   jContentPane.add(getJButton3(), null);  }  return jContentPane; } /**  * This method initializes jTextArea   *    * @return javax.swing.JTextArea   */ private JTextArea getJTextArea() {  if (jTextArea == null) {   jTextArea = new JTextArea();   jTextArea.setText("留言内容：");   jTextArea.setEditable(false);  }  return jTextArea; } /**  * This method initializes jScrollPane   *    * @return javax.swing.JScrollPane   */ private JScrollPane getJScrollPane() {  if (jScrollPane == null) {   jScrollPane = new JScrollPane();   jScrollPane.setBounds(new Rectangle(22, 49, 534, 347));   jScrollPane.setViewportView(getJTextArea());  }  return jScrollPane; } /**  * This method initializes jComboBox   *    * @return javax.swing.JComboBox   */ private JComboBox getJComboBox() {  if (jComboBox == null) {   jComboBox = new JComboBox();   jComboBox.setBounds(new Rectangle(110, 407, 100, 24));   String[] mycbox={
  "管理员","博主","游客"};   jComboBox.addItem(mycbox[0]);   jComboBox.addItem(mycbox[1]);   jComboBox.addItem(mycbox[2]);  }  return jComboBox; } /**  * This method initializes jTextField   *    * @return javax.swing.JTextField   */ private JTextField getJTextField() {  if (jTextField == null) {   jTextField = new JTextField();   jTextField.setBounds(new Rectangle(280, 407, 231, 200));  }  return jTextField; } /**  * This method initializes jButton   *    * @return javax.swing.JButton   */ private JButton getJButton() {  if (jButton == null) {   jButton = new JButton();   jButton.setBounds(new Rectangle(505, 407, 70, 24));   jButton.setText("发帖");   jButton.addActionListener(new java.awt.event.ActionListener() {    public void actionPerformed(java.awt.event.ActionEvent e) {     Date date = new Date();     jTextArea.setText(jTextArea.getText()+"\r\n"+date.toString()+ "  " + jComboBox.getSelectedItem().toString()+"   留言："+jTextField.getText());    }   });  }  return jButton; } /**  * This method initializes jButton1   *    * @return javax.swing.JButton   */ private JButton getJButton1() {  if (jButton1 == null) {   jButton1 = new JButton();   jButton1.setBounds(new Rectangle(565, 51, 60, 32));   jButton1.setText("删帖");   jButton1.addActionListener(new java.awt.event.ActionListener() {    public void actionPerformed(java.awt.event.ActionEvent e) { //    jTextArea.setText("留言内容：");     //  if(jComboBox.getSelectedItem().toString() == "管理员" || jComboBox.getSelectedItem().toString() =="博主" )｛    }   });  }  return jButton1; } /**  * This method initializes jButton2   *    * @return javax.swing.JButton   */ private JButton getJButton2() {  if (jButton2 == null) {   jButton2 = new JButton();   jButton2.setBounds(new Rectangle(560, 112, 80, 32));   jButton2.setText("从头浏览");   jButton2.addActionListener(new java.awt.event.ActionListener() {    public void actionPerformed(java.awt.event.ActionEvent e) {     jTextArea.setCaretPosition(0);    }   });  }  return jButton2; } /**  * This method initializes jButton3   *    * @return javax.swing.JButton   */ private JButton getJButton3() {  if (jButton3 == null) {   jButton3 = new JButton();   jButton3.setBounds(new Rectangle(560, 173, 80, 32));   jButton3.setText("从尾浏览");   jButton3.addActionListener(new java.awt.event.ActionListener() {    public void actionPerformed(java.awt.event.ActionEvent e) {     jTextArea.setCaretPosition((int)jTextArea.getText().length());    }   });  }  return jButton3; } public static void main(String args[]){  new jiang1(); }}