交互问题JTextArea和JScrollBar

Question

我遇到了一些在互联网上找不到的问题。我使用JTextArea和JScrollBar。当填充JTextArea窗口时，它会增加。这很可能是由于滚动，因为如果没有滚动，它在旧类中可以工作，但在填充时不可能写更多内容，所以我决定添加滚动。

启动

问题

旧代码：

private static final String IP_ADDRESS = "192.168.56.1";
private static final int PORT = 8000;
private static final int WIDTH = 600;
private static final int HEIGHT = 400;
private final JTextArea log = new JTextArea();
private final JTextField fieldNickName = new JTextField("Admin");
private final JTextField fieldInput = new JTextField();
private TCPConnection connection;
private ClientWindow(){
setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
setSize(WIDTH, HEIGHT);
setLocationRelativeTo(null);//-
setAlwaysOnTop(true);//-
log.setEditable(false);
log.setLineWrap(true); //-
add(log, BorderLayout.CENTER);
fieldInput.addActionListener(this);
add(fieldInput, BorderLayout.SOUTH);
add(fieldNickName, BorderLayout.NORTH);
setVisible(true);
try {
connection = new TCPConnection(this, IP_ADDRESS, PORT);
} catch (IOException ex) {
printMessage("Database exception: " + ex);
}
}
public static void goToChat(){
SwingUtilities.invokeLater(new Runnable() {
@Override
public void run() {
new ClientWindow();
}
});
}
@Override
public void actionPerformed(ActionEvent e) {
String message = fieldInput.getText();
if (message.trim().equals("")) return;
fieldInput.setText(null);
connection.sendString(fieldNickName.getText() + ": " + message);
}
@Override
public void onConnectionReady(TCPConnection tcpConnection) {
printMessage("Database ready ...");
}
@Override
public void onReceiveString(TCPConnection tcpConnection, String value) {
printMessage(value);
}
@Override
public void onDisconnect(TCPConnection tcpConnection) {
printMessage("Database close!");
}
@Override
public void onException(TCPConnection tcpConnection, Exception ex) {
printMessage("Database exception: " + ex);
}
private synchronized void printMessage(final String message){
SwingUtilities.invokeLater(new Runnable() {
@Override
public void run() {
log.append(message + "n");
log.setCaretPosition(log.getDocument().getLength());
}
});
}

}

现在：

private static final String IP_ADDRESS = "192.168.56.1";
private static final int PORT = 8000;
private static final String nickname = ClientEntrance.getNickname();
private static CopyOnWriteArrayList<String> allNickname = new CopyOnWriteArrayList<>();
private static ConcurrentHashMap<String, String> hashMap= new ConcurrentHashMap<>();
private JLabel jLabel1;
private JLabel labelForNickname;
private JLabel jLabel3;
private static JLabel jLabel4;
private JScrollBar jScrollBar1;
private JTextField jTextField1;
private JTextField fieldInput;
private JTextArea log;
private TCPConnection connection;
private ClientWindow() {
initComponents();
try {
connection = new TCPConnection(this, IP_ADDRESS, PORT);
} catch (IOException ex) {
printMessage("Database exception: " + ex);
}
}
private void initComponents() {
allNickname.add(nickname);
jLabel1 = new JLabel();
jTextField1 = new JTextField();
log = new JTextArea(10, 10);
jScrollBar1 = new JScrollBar();
fieldInput = new JTextField();
labelForNickname = new JLabel();
jLabel3 = new JLabel();
jLabel4 = new JLabel();
log.setEditable(false);
jLabel1.setText("jLabel1");
jTextField1.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent evt) {
jTextField1ActionPerformed(evt);
}
});
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
setResizable(false);
setAlwaysOnTop(true);
setLocationRelativeTo(null);
log.setWrapStyleWord(true);
log.setLineWrap(true);
DefaultCaret caret = (DefaultCaret)log.getCaret();
caret.setUpdatePolicy(DefaultCaret.NEVER_UPDATE);
fieldInput.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent evt) {
messageActionPerformed(evt);
}
});
labelForNickname.setText("Your nickname: " + nickname);
jLabel3.setText("Users online:");
addNewNicknames();
String all = "";
for (String s : allNickname) {
all += s + "n";
}//FIXME: Threads!!!!
jLabel4.setVerticalAlignment(SwingConstants.TOP);
GroupLayout layout = new GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(GroupLayout.Alignment.LEADING)
.addGroup(GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
.addGap(22, 22, 22)
.addGroup(layout.createParallelGroup(GroupLayout.Alignment.LEADING)
.addComponent(labelForNickname, GroupLayout.Alignment.TRAILING, GroupLayout.DEFAULT_SIZE, 529, Short.MAX_VALUE)
.addComponent(fieldInput)
.addComponent(log))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(jScrollBar1, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE)
.addGap(26, 26, 26)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(jLabel4, GroupLayout.PREFERRED_SIZE, 183, GroupLayout.PREFERRED_SIZE)
.addComponent(jLabel3, GroupLayout.PREFERRED_SIZE, 173, GroupLayout.PREFERRED_SIZE))
.addContainerGap())
);
layout.setVerticalGroup(
layout.createParallelGroup(GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addContainerGap()
.addComponent(labelForNickname, GroupLayout.PREFERRED_SIZE, 16, GroupLayout.PREFERRED_SIZE)
.addGap(8, 8, 8)
.addGroup(layout.createParallelGroup(GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addGroup(layout.createParallelGroup(GroupLayout.Alignment.LEADING, false)
.addComponent(log)
.addComponent(jScrollBar1, GroupLayout.DEFAULT_SIZE, 517, Short.MAX_VALUE))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 13, Short.MAX_VALUE)
.addComponent(fieldInput, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE)
.addGap(19, 19, 19))
.addGroup(layout.createSequentialGroup()
.addComponent(jLabel3)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(jLabel4, GroupLayout.DEFAULT_SIZE, GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addGap(31, 31, 31))))
);
jLabel4.getAccessibleContext().setAccessibleName("");
pack();
}
private void jTextField2ActionPerformed(ActionEvent evt) {
}
private void jTextField1ActionPerformed(ActionEvent evt) {
}
public static void goToChat(String id, String nickname) {
CustomizeItemsJavaFX.start(ClientWindow.class);
EventQueue.invokeLater(new Runnable() {
public void run() {
new ClientWindow().setVisible(true);
}
});
}
public void messageActionPerformed(ActionEvent e) {
String message = fieldInput.getText();
if (message.trim().equals("")) return;
fieldInput.setText(null);
connection.sendString(nickname + ": " + message);
// Database.writeToDatabaseNewMessages(message);
}
@Override
public void onConnectionReady(TCPConnection tcpConnection) {
printMessage("Database ready ...");
}
@Override
public void onReceiveString(TCPConnection tcpConnection, String value) {
printMessage(value);
}
@Override
public void onDisconnect(TCPConnection tcpConnection) {
printMessage("Database close!");
}
@Override
public void onException(TCPConnection tcpConnection, Exception ex) {
printMessage("Database exception: " + ex);
}
private synchronized void printMessage(final String message){
SwingUtilities.invokeLater(new Runnable() {
@Override
public void run() {
log.append(message + "n");
log.setCaretPosition(log.getDocument().getLength());
}
});
}
private synchronized static void addNewNicknames(){
StringBuilder all = new StringBuilder();
for (String s : allNickname) all.append(s).append("n");
jLabel4.setText(all.toString());
}

}

请告诉我。我找不到答案。

Answer 1

停止。阅读：

• 如何使用文本区域
• 如何使用滚动窗格

可能还有JScrollPaneJavaDocs

完成后，更新您的代码，将JTextArea封装在JScrollPane中，之后您将获得对滚动条的适当支持