如何实现滚动条的自动滚动到textarea的末尾

Question

//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;
}

Answer 1

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

Answer 2

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！！！

Answer 3

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: [email protected]</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);
    }
}

Answer 4

还有，你不要用append，试试用settext!!!!!

Answer 5

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 ：）

Answer 6

ok.谢谢大家了。特别是newman0708。。谢咯