我有一个JFrame
含有一个JScrollPane
含有一个JPanel
.
The JPanel
包含一堆JTextArea
s。
我正在向其中加载大量文本(大约 8k-10k 个字符)。
布局工作正常,尽管滚动有点滞后。
真正的问题似乎是JPanel
, JScrollPane
and JViewport
有一个硬性的 32767 大小限制,所以当任何JTextArea
如果超过该值,则无法进一步滚动以显示文本的最后 1/3。
下面您可以看到该问题的一个最小示例。我用的是NetBeansJFrame
设计师所以它可能有点长,但我对默认值唯一改变的是JTextArea
s 是 的直接子代JPanel
、滚动条策略以及稍大的字体大小:
public class NewJFrame extends javax.swing.JFrame {
/**
* Creates new form NewJFrame
*/
public NewJFrame() {
initComponents();
}
/**
* This method is called from within the constructor to initialize the form.
* WARNING: Do NOT modify this code. The content of this method is always
* regenerated by the Form Editor.
*/
@SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">
private void initComponents() {
jScrollPane1 = new javax.swing.JScrollPane();
jPanel1 = new javax.swing.JPanel();
jTextArea1 = new javax.swing.JTextArea();
jTextArea2 = new javax.swing.JTextArea();
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
jScrollPane1.setHorizontalScrollBarPolicy(javax.swing.ScrollPaneConstants.HORIZONTAL_SCROLLBAR_NEVER);
jScrollPane1.setVerticalScrollBarPolicy(javax.swing.ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS);
jTextArea1.setColumns(20);
jTextArea1.setFont(new java.awt.Font("Monospaced", 0, 14)); // NOI18N
jTextArea1.setRows(5);
jTextArea2.setColumns(20);
jTextArea2.setFont(new java.awt.Font("Monospaced", 0, 14)); // NOI18N
jTextArea2.setRows(5);
jTextArea2.setText("Some long text...");
javax.swing.GroupLayout jPanel1Layout = new javax.swing.GroupLayout(jPanel1);
jPanel1.setLayout(jPanel1Layout);
jPanel1Layout.setHorizontalGroup(
jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jPanel1Layout.createSequentialGroup()
.addComponent(jTextArea1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(jTextArea2, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(0, 0, 0))
);
jPanel1Layout.setVerticalGroup(
jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jPanel1Layout.createSequentialGroup()
.addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(jTextArea1, javax.swing.GroupLayout.DEFAULT_SIZE, 342, Short.MAX_VALUE)
.addComponent(jTextArea2))
.addGap(0, 0, 0))
);
jScrollPane1.setViewportView(jPanel1);
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(jScrollPane1)
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(jScrollPane1, javax.swing.GroupLayout.DEFAULT_SIZE, 96, Short.MAX_VALUE)
);
pack();
}// </editor-fold>
/**
* @param args the command line arguments
*/
public static void main(String args[]) {
final NewJFrame f = new NewJFrame();
/* Set the Nimbus look and feel */
//<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
/* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
* For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html
*/
try {
for(javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels())
if("Nimbus".equals(info.getName())) {
javax.swing.UIManager.setLookAndFeel(info.getClassName());
break;
}
}catch(ClassNotFoundException ex) {
java.util.logging.Logger.getLogger(NewJFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
}catch(InstantiationException ex) {
java.util.logging.Logger.getLogger(NewJFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
}catch(IllegalAccessException ex) {
java.util.logging.Logger.getLogger(NewJFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
}catch(javax.swing.UnsupportedLookAndFeelException ex) {
java.util.logging.Logger.getLogger(NewJFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
}
//</editor-fold>
/* Create and display the form */
java.awt.EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
f.setVisible(true);
}
});
StringBuilder txt = new StringBuilder();
for(int i=0; i<10000; i++)
txt.append(i).append("\n");
f.jTextArea1.setText(txt.toString());
txt = new StringBuilder();
txt.append("JTextArea height: ").append(f.jTextArea1.getHeight()).append('\n');
txt.append("JTextArea rows: ").append(f.jTextArea1.getRows()).append('\n');
txt.append("JScrollPane height:").append(f.jScrollPane1.getHeight()).append('\n');
txt.append("JViewport height:").append(f.jScrollPane1.getViewport().getHeight()).append('\n');
txt.append("JPanel height:").append(f.jPanel1.getHeight()).append('\n');
f.jTextArea2.setText(txt.toString());
}
// Variables declaration - do not modify
private javax.swing.JPanel jPanel1;
private javax.swing.JScrollPane jScrollPane1;
private javax.swing.JTextArea jTextArea1;
private javax.swing.JTextArea jTextArea2;
// End of variables declaration
}
如果运行此命令并滚动到底部,您预计会看到计数达到 10 000,但实际上只达到 1637,并且您可以看到下一行的顶部像素几乎没有显示。
我已经尝试过setMaximumSize
and setSize
on the JPanel
, the JScrollPane
和它的JViewport
但一切都没有改变。我还有些困惑的是,尽管有 10k 行文本,其中一些可以滚动到足以查看,但getRows()
and getSize()
方法返回原始值。
当我想要可滚动的情况时,处理这种情况的正确方法是什么JTextArea
大于 32767?