Java 如何保持 JTextArea 的大小不变？
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How To Keep Size Of JTextArea constant?
提问by Supereme
I'm using an object of JTextArea in my application which deals with sending sms.
我在我的应用程序中使用 JTextArea 对象来处理发送短信。
I've used a DocumentFilter so as to allow only 160 characters to be typed in the textarea but now, I want the size of the textarea to be constant. it goes on increasing if I keep writing on the same line without pressing 'enter' key or even when I keep on pressing only Enterkey. I tried once using 'scrollbar' too but the problem remains same. Suggest me something over this. Below is my code. Please check it.
我使用了 DocumentFilter 以便只允许在 textarea 中输入 160 个字符，但现在，我希望 textarea 的大小保持不变。如果我继续在同一行上书写而不按“回车”键，或者即使我继续只按一个Enter键，它也会继续增加。我也尝试过使用“滚动条”，但问题仍然存在。建议我解决这个问题。下面是我的代码。请检查一下。
class Send_sms extends JPanel implements ActionListener,DocumentListener
{
JButton send;
JTextArea smst;
JLabel title,limit;
JPanel mainp,titlep,sendp,wrap,titlewrap,blankp1,blankp2,sendwrap;
JScrollPane scroll;
Border br,blackbr;
Boolean flag = false;
PlainDocument plane;
public static final int LINES = 4;
public static final int CHAR_PER_LINE = 40;
//character limit 160 for a sms
public Send_sms()
{
br = BorderFactory.createLineBorder(Color.RED);
blackbr = BorderFactory.createEtchedBorder(EtchedBorder.RAISED,Color.DARK_GRAY,Color.GRAY);
setBorder(blackbr);
title = new JLabel("Enter the text you want to send!");
title.setFont(new Font("",Font.BOLD,17));
limit = new JLabel(""+charCount+" Characters");
smst = new JTextArea(LINES,CHAR_PER_LINE);
smst.setSize(100,100);
plane = (PlainDocument)smst.getDocument();
//adding DocumentSizeFilter 2 keep track of characters entered
plane.setDocumentFilter(new DocumentSizeFilter(charCount));
plane.addDocumentListener(this);
send = new JButton("Send");
send.setToolTipText("Click Here To Send SMS");
send.addActionListener(this);
//scroll = new JScrollPane(smst);
//scroll.setPreferredSize(new Dimension(200,200));
//scroll.setVerticalScrollBarPolicy(null);
//scroll.setHorizontalScrollBarPolicy(null);
smst.setBorder(br);
blankp1 = new JPanel();
blankp2 = new JPanel();
titlep = new JPanel(new FlowLayout(FlowLayout.CENTER));
titlewrap = new JPanel(new GridLayout(2,1));
mainp = new JPanel(new BorderLayout());
sendwrap = new JPanel(new GridLayout(3,1));
sendp = new JPanel(new FlowLayout(FlowLayout.CENTER));
wrap = new JPanel(new BorderLayout());
titlep.add(title);
titlewrap.add(titlep);
titlewrap.add(blankp1);
sendp.add(send);
sendwrap.add(limit);
sendwrap.add(blankp2);
sendwrap.add(sendp);
wrap.add(smst,BorderLayout.CENTER);
mainp.add(titlewrap,BorderLayout.NORTH);
mainp.add(wrap,BorderLayout.CENTER);
mainp.add(sendwrap,BorderLayout.SOUTH);
add(mainp);
}
public void actionPerformed(ActionEvent e)
{
Vector<Vector<String>> info = new Vector<Vector<String>> ();
Vector<String> numbers = new Vector<String>();
if(e.getSource() == send)
{
//Call a function to send he message to all the clients using text
//charCount = 165;
String msg = smst.getText();
if(msg.length() == 0)
JOptionPane.showMessageDialog(null,"Please Enter Message","Error",JOptionPane.ERROR_MESSAGE);
else
{
// System.out.println("Message:"+msg);
Viewdata frame = new Viewdata(msg);
limit.setText(""+charCount+" Characters");
charCount = 160;
}
}
}
public void insertUpdate(DocumentEvent e)
{
System.out.println("The legth:(insert) "+e.getLength());
for(int i = 0;i<e.getLength(); i++)
{
if(charCount >0)
charCount--;
else
break;
}
limit.setText(""+charCount+" Characters");
}
public void removeUpdate(DocumentEvent e)
{
//System.out.println("The legth(remove): "+e.getLength());
for(int i = 0;i<e.getLength(); i++)
{
charCount++;
}
limit.setText(""+charCount+" Characters");
}
public void changedUpdate(DocumentEvent e)
{
//System.out.println("The legth(change): "+e.getLength());
}
}//end Send_sms
回答by Roman
you need to specify:
您需要指定：
textArea.setColumns (160);
textArea.setLineWrap (true);
textArea.setWrapStyleWord (false); //default
But the real problem is that you allow to input more than 160 characters. You need to create some kind of validator which will skip all inputed characters when there are already 160 characters written.
但真正的问题是您允许输入超过 160 个字符。您需要创建某种验证器，当已经写入 160 个字符时，它将跳过所有输入的字符。
回答by camickr
Sound like you are creating the text area using
听起来你正在使用创建文本区域
JTextArea textArea = new JTextArea();
When using this format the text area doesn't have a preferred size so it keeps on growing. If you use:
使用这种格式时，文本区域没有首选大小，因此它会不断增长。如果您使用：
JTextArea textArea = new JTextArea(2, 30);
JScrollPane scrollPane = new JScrollPane( textArea );
Then the text area will have a preferred size of 2 rows and (roughly) 30 columns. As you type when you exceed the preferred width the horizontal scrollbar will appear. Or if you turn on wrapping, then the text will wrap and a vertical scrollbar will appear.
然后文本区域的首选大小为 2 行和（大约）30 列。当您输入超过首选宽度时，将出现水平滚动条。或者，如果您打开环绕，则文本将环绕并出现垂直滚动条。
回答by Kannan Ekanath
Initialise the textArea with a document that extends PlainDocument and in the insertString method limit the characters to 160
使用扩展 PlainDocument 的文档初始化 textArea，并在 insertString 方法中将字符限制为 160
