swing如何在java中的textArea中新添加的文本末尾自动显示插入符号？

Question

Possible Duplicate:
Automatically scroll to the bottom of a text area

我有TextArea组件。在不同的情况下，我应该附加文本。我希望插入符号出现在新附加文本的末尾，如果文本太大，则自动向下滚动

textAreaStatus = new WebTextArea(
            "1- Click on the refresh icon to get newest file.\n" +
                    "2- Select destination if needed.\n" +
                    "3- Click download button to start downloading.\n");
    textAreaStatus.setBackground(Color.black);
    textAreaStatus.setCaretPosition(textAreaStatus.getText().length());
    textAreaStatus.getCaret().setVisible(true);

Answer 1

希望这段代码能对您有所帮助。你必须这么做

int len = textArea.getDocument().getLength();
textArea.setCaretPosition(len);

用于包装文本，使其向下滚动，因为长度超过实际视图使用的长度

textArea.setLineWrap(true);

下面是一个示例程序供您理解

import java.awt.BorderLayout;

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JButton;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;

public class CarotPosition extends JFrame
{
    private JPanel panel;
    private JTextArea textArea;
    private JScrollPane scrollPane;
    private JButton button;

    public CarotPosition()
    {
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setLocationRelativeTo(null);

        panel = new JPanel();
        panel.setLayout(new BorderLayout());

        textArea = new JTextArea();
        scrollPane = new JScrollPane(textArea);
        textArea.setLineWrap(true);

        button = new JButton("Click to add Text");
        button.addActionListener(new ActionListener()
            {
                public void actionPerformed(ActionEvent ae)
                {
                    textArea.append("Some NEW TEXT is here...");
                    int len = textArea.getDocument().getLength();
                    textArea.setCaretPosition(len);
                    textArea.requestFocusInWindow();
                }
            });

        setContentPane(panel);
        panel.add(scrollPane, BorderLayout.CENTER);
        panel.add(button, BorderLayout.PAGE_END);

        pack();
        setVisible(true);   
    }

    public static void main(String... args)
    {
        javax.swing.SwingUtilities.invokeLater(new Runnable()
            {
                public void run()
                {
                    new CarotPosition();
                }
            });
    }
}

希望这对你有所帮助

问候