Java 追加后如何自动向下滚动JTextArea？
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How to auto scroll down JTextArea after append?
提问by Iter Ator
I've created a JFrame, with a JTextArea. I would like to scroll down the textarea automatically, after each append. How should I manage it?
我创建了一个带有 JTextArea 的 JFrame。我想在每次追加后自动向下滚动文本区域。我应该如何管理它？
I've tried log.setCaretPosition(log.getDocument().getLength());, but nothing changed.
我试过了log.setCaretPosition(log.getDocument().getLength());，但没有任何改变。
package scrollit;
import java.awt.*;
import javax.swing.*;
import static javax.swing.JFrame.EXIT_ON_CLOSE;
public class ScrollIt extends JFrame {
public static void main(String[] args) {
ScrollIt sc = new ScrollIt();
}
public ScrollIt() {
super();
JTextArea log = new JTextArea();
log.setPreferredSize(new Dimension(50,50));
setDefaultCloseOperation(EXIT_ON_CLOSE);
add(log);
pack();
setVisible(true);
log.append("a\n");
log.append("b\n");
log.append("c\n");
log.append("d\n");
log.append("e\n");
log.append("f\n");
}
}
采纳答案by mKorbel
there are two ways (but JTextAreamust be placed in JScrollPane)
有两种方式（但JTextArea必须放在JScrollPane 中）
a) set Caret(correct of ways)
a）设置插入符号（正确的方式）
e.g.
例如
DefaultCaret caret = (DefaultCaret) log.getCaret(); caret.setUpdatePolicy(DefaultCaret.ALWAYS_UPDATE);
DefaultCaret caret = (DefaultCaret) log.getCaret(); caret.setUpdatePolicy(DefaultCaret.ALWAYS_UPDATE);
b) moving with JScrollBar(from JScrollPane) to its max value
b) 随着JScrollBar(from ) 移动JScrollPane到它的最大值
回答by user3498796
Mine is a little simpler and efficient. We set the caret to the length of the text to put it at the end like so.
我的有点简单和高效。我们将插入符号设置为文本的长度以将其放在最后。
public void appendText(String str){
txtArea.append(str + "\n");
scrollDown();
}
public void scrollDown(){
txtArea.setCaretPosition(txtArea.getText().length());
}
