如何实现滚动条的自动滚动到textarea的末尾

[bluedream2003]

我做了个聊天室，在textarea里放置了Jscrollpane，在收到信息打印到textarea上的时候，当textarea满屏时滚动条不能自动滚动，要用户自己滚动才可以看到信息，很不方便，请问各位高手应该怎么做？？

[cowboy1114]

//我的好象可以自动滚动，你看一下
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class ScrollApp
{
public static void main(String[] args)
{
ScrollFrame frame=new ScrollFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.show();
}
}

class ScrollFrame extends JFrame
{
public ScrollFrame()
{

setTitle("Scroll Demo");
setSize(400,500);

Container contentPane=getContentPane();

show=new JTextArea(20,10);
JScrollPane pane=new JScrollPane(show);

addText=new JButton("ADD TEXT");

addText.addActionListener(
new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
show.append("gsdklfsdljfsdlkjfdsljfdslkfjslk\n"+
"sdfjsdkfjsdlkjfkssdjfkdsfjdksjfksdsdfdssdfsdds\n"+
"sdfjsdkfjsdlkjfkssdjfkdsfjdksjfksdsdfdssdfsdds\n"+
"sdfjsdkfjsdlkjfkssdjfkdsfjdksjfksdsdfdssdfsdds\n"+
"sdfjsdkfjsdlkjfkssdjfkdsfjdksjfksdsdfdssdfsdds\n"+
"sdfjsdkfjsdlkjfkssdjfkdsfjdksjfksdsdfdssdfsdds\n"+
"sdfjsdkfjsdlkjfkssdjfkdsfjdksjfksdsdfdssdfsdds\n"+
"sdfjsdkfjsdlkjfkssdjfkdsfjdksjfksdsdfdssdfsdds\n"+
"sdfjsdkfjsdlkjfkssdjfkdsfjdksjfksdsdfdssdfsdds\n"+
"sdfjsdkfjsdlkjfkssdjfkdsfjdksjfksdsdfdssdfsdds\n"+
"sdfjsdkfjsdlkjfkssdjfkdsfjdksjfksdsdfdssdfsdds\n"+
"sdfjsdkfjsdlkjfkssdjfkdsfjdksjfksdsdfdssdfsdds\n"+
"sdfjsdkfjsdlkjfkssdjfkdsfjdksjfksdsdfdssdfsdds\n"+
"sdfjsdkfjsdlkjfkssdjfkdsfjdksjfksdsdfdssdfsdds\n"+
"sdfjsdkfjsdlkjfkssdjfkdsfjdksjfksdsdfdssdfsdds\n"+
"sdfjsdkfjsdlkjfkssdjfkdsfjdksjfksdsdfdssdfsdds\n"+
"sdfjsdkfjsdlkjfkssdjfkdsfjdksjfksdsdfdssdfsdds\n"+
"sdfjsdkfjsdlkjfkssdjfkdsfjdksjfksdsdfdssdfsdds");
}
});

contentPane.add(pane,BorderLayout.CENTER);
contentPane.add(addText,BorderLayout.SOUTH);




}

JButton addText;
JTextArea show;
}

[newman0708]

133.可以将光标定位于指定的位置（滚动效果）
this.jTextArea2 .setCaretPosition(0);

[cyicecream]

呵呵，如此的效果是不行的，触动滚动条后就没办法自动了。
我也想过，不过没实现，关注~~~~~

[bluedream2003]

自己直接append上去就可以实现自动滚动。但一接收到其他用户的信息时。就一直不能滚动了。实在是疑惑。。。。。？？？
大家好好想想啊。我想得快疯了！！！

[newman0708]

你根据我的程序自己变动一下，应该没有问题的。

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
/**
* <p>Title: This follow is newman's writing</p>
* <p>Description: I want better writing ,instead of best one!</p>
* <p>Copyright: Copyright (c) 2002</p>
* <p>Company: [e-mail]</p>
* @author Newman
* @version 1.0
*/

public class ScrollFrame extends JFrame{
JPanel jPanel1 = new JPanel();
JScrollPane jScrollPane1 = new JScrollPane();
BorderLayout borderLayout1 = new BorderLayout();
JTextArea jTextArea1 = new JTextArea();
JPanel jPanel2 = new JPanel();
String str="gsdklfsdljfsdlkjfdsljfdslkfjslk\n"+
"sdfjsdkfjsdlkjfkssdjfkdsfjdksjfksdsdfdssdfsdds\n"+
"sdfjsdkfjsdlkjfkssdjfkdsfjdksjfksdsdfdssdfsdds\n"+
"sdfjsdkfjsdlkjfkssdjfkdsfjdksjfksdsdfdssdfsdds\n"+
"sdfjsdkfjsdlkjfkssdjfkdsfjdksjfksdsdfdssdfsdds\n"+
"sdfjsdkfjsdlkjfkssdjfkdsfjdksjfksdsdfdssdfsdds\n"+
"sdfjsdkfjsdlkjfkssdjfkdsfjdksjfksdsdfdssdfsdds\n"+
"sdfjsdkfjsdlkjfkssdjfkdsfjdksjfksdsdfdssdfsdds\n"+
"sdfjsdkfjsdlkjfkssdjfkdsfjdksjfksdsdfdssdfsdds\n"+
"sdfjsdkfjsdlkjfkssdjfkdsfjdksjfksdsdfdssdfsdds\n"+
"sdfjsdkfjsdlkjfkssdjfkdsfjdksjfksdsdfdssdfsdds\n"+
"sdfjsdkfjsdlkjfkssdjfkdsfjdksjfksdsdfdssdfsdds\n"+
"sdfjsdkfjsdlkjfkssdjfkdsfjdksjfksdsdfdssdfsdds\n"+
"sdfjsdkfjsdlkjfkssdjfkdsfjdksjfksdsdfdssdfsdds\n"+
"sdfjsdkfjsdlkjfkssdjfkdsfjdksjfksdsdfdssdfsdds\n"+
"sdfjsdkfjsdlkjfkssdjfkdsfjdksjfksdsdfdssdfsdds\n"+
"sdfjsdkfjsdlkjfkssdjfkdsfjdksjfksdsdfdssdfsdds\n"+
"end sdfjsdkfjsdlkjfkssdjfkdsfjdksjfksdsdfdssdfs\n";
JButton jButton1 = new JButton();
JButton jButton2 = new JButton();


public ScrollFrame() {
try {
jbInit();
}
catch(Exception e) {
e.printStackTrace();
}
}
public static void main(String[] args) {
ScrollFrame scrollFrame1 = new ScrollFrame();
scrollFrame1.setSize(200,300);
scrollFrame1.show();
}
private void jbInit() throws Exception {
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE );
jPanel1.setLayout(borderLayout1);
jTextArea1.setText(this.str );
jScrollPane1.setHorizontalScrollBarPolicy(JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS);
jScrollPane1.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
jButton1.setText("end");
jButton1.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(ActionEvent e) {
jButton1_actionPerformed(e);
}
});
jButton2.setText("start");
jButton2.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(ActionEvent e) {
jButton2_actionPerformed(e);
}
});
this.getContentPane().add(jPanel1, BorderLayout.CENTER);
jPanel1.add(jScrollPane1, BorderLayout.CENTER);
jPanel1.add(jPanel2, BorderLayout.SOUTH);
jPanel2.add(jButton1, null);
jPanel2.add(jButton2, null);
jScrollPane1.getViewport().add(jTextArea1, null);
}

void jButton1_actionPerformed(ActionEvent e) {//end
int height=10;
Point p = new Point();
p.setLocation(0,this.jTextArea1.getLineCount()*height);
this.jScrollPane1.getViewport().setViewPosition(p);
}

void jButton2_actionPerformed(ActionEvent e) {//start
Point p = new Point(0,0);
this.jScrollPane1.getViewport().setViewPosition(p);
}
}

[cyicecream]

呵呵，我的情况和你的一样，必须要从服务端接收信息

[cyicecream]

不错的例子，明天一定能解决。下班了，收工

[alemjann]

@_@ ing

[newman0708]

还有，你不要用append，试试用settext!!!!!

[zhaoao]

关注！

[bluedream2003]

ok.谢谢大家了。特别是newman0708。。谢咯

[cyicecream]

楼主，我的已经搞定了，你还搞定了没？
从newman0708(nch)的例子可以解决这个问题。多想想 ：）

[newman0708]

谢谢我有什么用，把分数结吧!