Java中JTextArea的自动动态扩展/收缩 [英] automatic dynamic expansion / contraction of JTextArea in Java
问题描述
我首先创建一个特定大小的JTextArea.用户可以在其中添加文本,但是如果文本太长(垂直或水平),它将被截断.我希望JTextArea自动扩展或收缩(用于删除文本).
I start off by creating a JTextArea of a specific size. The user can add text within it but it will get cut off if it becomes too long (vertically or horizontally). I want the JTextArea to automatically expand or contract (for deletion of text).
将来我可能会允许用户更改字体和字体大小,因此,如果我可以避免使事物增加/减少一定的大小,那将是很好的选择.
I may allow users to change font and font size in the future, so it would be good if I could avoid making things increase/decrease by a certain size.
我当前正在使用边界来调整我的JTextArea的大小.也许我应该按行和列调整大小,并使用侦听器并适当执行操作?
I am currently using bounds to size my JTextArea. Perhaps I should size by rows and columns and use a listener and act appropriately?
提前谢谢!
推荐答案
我无法想象您为什么要这样做,为什么不将JTextArea放在JScrollPane中,但是好的,我会继续工作. .也许像这样:
I can't imagine why you'd want to do this, why not put a JTextArea in a JScrollPane, but ok, i'll play along... Maybe something like this:
import java.awt.Container;
import javax.swing.Box;
import javax.swing.BoxLayout;
import javax.swing.JFrame;
import javax.swing.JTextArea;
import javax.swing.SwingUtilities;
import javax.swing.event.DocumentEvent;
import javax.swing.event.DocumentListener;
import javax.swing.text.BadLocationException;
public class Expander extends JFrame {
private final JTextArea area;
private int hSize = 1;
private int vSize = 1;
public Expander() {
Container cp = getContentPane();
cp.setLayout(new BoxLayout(cp, BoxLayout.Y_AXIS));
cp.add(Box.createHorizontalGlue());
area = new JTextArea(vSize, hSize);
cp.add(area);
cp.add(Box.createHorizontalGlue());
area.getDocument().addDocumentListener(new DocumentListener() {
@Override
public void insertUpdate(DocumentEvent e) {
adjust();
}
@Override
public void removeUpdate(DocumentEvent e) {
adjust();
}
@Override
public void changedUpdate(DocumentEvent e) {
adjust();
}
});
pack();
}
private void adjust() {
int maxColumns = getMaxColumns();
if ((area.getLineCount() != vSize) || (maxColumns != hSize)) {
hSize = maxColumns;
vSize = area.getLineCount();
SwingUtilities.invokeLater(new Runnable() {
@Override
public void run() {
area.setColumns(hSize);
area.setRows(vSize);
Expander.this.doLayout();
Expander.this.pack();
}
});
}
}
private int getMaxColumns() {
int startOffset = 0;
int maxColumns = 0;
for (int i = 0; i < area.getLineCount(); i++) {
try {
int endOffset = area.getLineEndOffset(i);
int lineSize = endOffset - startOffset;
if (lineSize > maxColumns) {
maxColumns = lineSize;
}
startOffset = endOffset;
} catch (BadLocationException ble) {
}
}
return maxColumns;
}
public static void main(String[] args) {
Expander e = new Expander();
e.setLocationRelativeTo(null);
e.setVisible(true);
}
}
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