我正在开发一个应用程序，该应用程序必须显示属于文本文档(注释)的元素列表。 如果从 NetBeans 本身的 SWING 编辑器复制元素，则一切正常。当我通过使用函数(add ())手动添加元素来从代码中执行此操作时，问题就出现了。 我需要制作一个可滚动列表，该列表由包含其自己元素的面板组成。
package notas.forms;
public class MainWindow extends javax.swing.JFrame
{
public MainWindow() {
initComponents();
this.setResizable(false);
}
@SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">
private void initComponents() {
jPanel3 = new javax.swing.JPanel();
jPanel1 = new javax.swing.JPanel();
jLabel4 = new javax.swing.JLabel();
jLabel5 = new javax.swing.JLabel();
jScrollPane1 = new javax.swing.JScrollPane();
jPanel2 = new javax.swing.JPanel();
jPanel4 = new javax.swing.JPanel();
jLabel2 = new javax.swing.JLabel();
jLabel1 = new javax.swing.JLabel();
jLabel3 = new javax.swing.JLabel();
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
setBackground(new java.awt.Color(255, 255, 255));
jPanel3.setBackground(new java.awt.Color(255, 255, 255));
jPanel1.setBackground(new java.awt.Color(255, 255, 255));
jPanel1.setBorder(javax.swing.BorderFactory.createLineBorder(new java.awt.Color(204, 204, 204)));
jLabel4.setIcon(new javax.swing.ImageIcon(getClass().getResource("/imagenes/grap.png"))); // NOI18N
jLabel5.setIcon(new javax.swing.ImageIcon(getClass().getResource("/imagenes/add.png"))); // NOI18N
javax.swing.GroupLayout jPanel1Layout = new javax.swing.GroupLayout(jPanel1);
jPanel1.setLayout(jPanel1Layout);
jPanel1Layout.setHorizontalGroup(
jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jPanel1Layout.createSequentialGroup()
.addContainerGap()
.addComponent(jLabel5)
.addGap(0, 0, Short.MAX_VALUE))
.addGroup(javax.swing.GroupLayout.Alignment.TRAILING, jPanel1Layout.createSequentialGroup()
.addContainerGap(149, Short.MAX_VALUE)
.addComponent(jLabel4)
.addGap(108, 108, 108))
);
jPanel1Layout.setVerticalGroup(
jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jPanel1Layout.createSequentialGroup()
.addGap(197, 197, 197)
.addComponent(jLabel4)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 167, Short.MAX_VALUE)
.addComponent(jLabel5)
.addContainerGap())
);
jScrollPane1.setBackground(new java.awt.Color(255, 255, 255));
jScrollPane1.setName("listaNotas"); // NOI18N
jPanel2.setBackground(new java.awt.Color(255, 255, 255));
jPanel4.setBackground(new java.awt.Color(255, 255, 255));
jPanel4.setBorder(javax.swing.BorderFactory.createLineBorder(new java.awt.Color(204, 204, 204)));
jPanel4.setEnabled(false);
jLabel2.setText("TITULO DE LA PUTA NOTA TENSANTE Y ASQUEROSA");
jLabel1.setIcon(new javax.swing.ImageIcon(getClass().getResource("/imagenes/trash.png"))); // NOI18N
jLabel3.setForeground(new java.awt.Color(153, 153, 153));
jLabel3.setText("3/12/2017");
javax.swing.GroupLayout jPanel4Layout = new javax.swing.GroupLayout(jPanel4);
jPanel4.setLayout(jPanel4Layout);
jPanel4Layout.setHorizontalGroup(
jPanel4Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jPanel4Layout.createSequentialGroup()
.addContainerGap()
.addGroup(jPanel4Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jPanel4Layout.createSequentialGroup()
.addComponent(jLabel2)
.addGap(0, 0, Short.MAX_VALUE))
.addGroup(jPanel4Layout.createSequentialGroup()
.addComponent(jLabel3)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addComponent(jLabel1)))
.addContainerGap())
);
jPanel4Layout.setVerticalGroup(
jPanel4Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(javax.swing.GroupLayout.Alignment.TRAILING, jPanel4Layout.createSequentialGroup()
.addContainerGap()
.addGroup(jPanel4Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
.addGroup(jPanel4Layout.createSequentialGroup()
.addGap(0, 0, Short.MAX_VALUE)
.addComponent(jLabel1))
.addGroup(jPanel4Layout.createSequentialGroup()
.addComponent(jLabel2)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 43, Short.MAX_VALUE)
.addComponent(jLabel3)))
.addContainerGap())
);
javax.swing.GroupLayout jPanel2Layout = new javax.swing.GroupLayout(jPanel2);
jPanel2.setLayout(jPanel2Layout);
jPanel2Layout.setHorizontalGroup(
jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jPanel2Layout.createSequentialGroup()
.addContainerGap()
.addComponent(jPanel4, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addContainerGap(95, Short.MAX_VALUE))
);
jPanel2Layout.setVerticalGroup(
jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jPanel2Layout.createSequentialGroup()
.addContainerGap()
.addComponent(jPanel4, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addContainerGap(1343, Short.MAX_VALUE))
);
jScrollPane1.setViewportView(jPanel2);
javax.swing.GroupLayout jPanel3Layout = new javax.swing.GroupLayout(jPanel3);
jPanel3.setLayout(jPanel3Layout);
jPanel3Layout.setHorizontalGroup(
jPanel3Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(javax.swing.GroupLayout.Alignment.TRAILING, jPanel3Layout.createSequentialGroup()
.addComponent(jScrollPane1, javax.swing.GroupLayout.PREFERRED_SIZE, 384, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
);
jPanel3Layout.setVerticalGroup(
jPanel3Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addComponent(jScrollPane1, javax.swing.GroupLayout.PREFERRED_SIZE, 0, Short.MAX_VALUE)
);
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addComponent(jPanel3, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(0, 0, Short.MAX_VALUE))
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(jPanel3, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
);
pack();
}// </editor-fold>
public static void main(String args[]) {
/* 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(MainWindow.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (InstantiationException ex) {
java.util.logging.Logger.getLogger(MainWindow.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (IllegalAccessException ex) {
java.util.logging.Logger.getLogger(MainWindow.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (javax.swing.UnsupportedLookAndFeelException ex) {
java.util.logging.Logger.getLogger(MainWindow.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
}
//</editor-fold>
/* Create and display the form */
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
new MainWindow().setVisible(true);
}
});
}
// Variables declaration - do not modify
private javax.swing.JLabel jLabel1;
private javax.swing.JLabel jLabel2;
private javax.swing.JLabel jLabel3;
private javax.swing.JLabel jLabel4;
private javax.swing.JLabel jLabel5;
private javax.swing.JPanel jPanel1;
private javax.swing.JPanel jPanel2;
private javax.swing.JPanel jPanel3;
private javax.swing.JPanel jPanel4;
private javax.swing.JScrollPane jScrollPane1;
// End of variables declaration
}
最佳答案
If from the SWING editor of NetBeans itself the elements are duplicated, everything works correctly. The problem comes when I do it from code by manually adding the elements with the function (add ()).
问题是 NetBeans 使用 GroupLayout 生成布局代码。 GroupLayout 很复杂，当您向面板添加组件时需要提供多个约束。
因此，当您使用 add(...) 方法时，您需要提供与 NetBeans 相同的约束。
但是，更简单的解决方案是不使用 NetBeans 生成 GUI 代码。相反，您可以控制布局管理并使代码更简单且更易于维护。
例如，您可以执行以下操作:
Box children = Box.createVerticalBox();
JPanel wrapper = new JPanel( new BorderLayout() );
wrapper.add(children, BorderLayout.Page_Start);
JScrollPane scrollPane = new JScrollPane( wrapper );
frame.add(scrollPane, BorderLayout.CENTER)'
现在，每当您想向滚动 Pane 添加新面板时，您只需执行以下操作:
children.add( a new child panel );
children.revalidate();
以上代码替换了 IDE 生成的所有 GroupLayout 代码。
另一个选择可能是使用GridBagLayout。它允许您向面板上的单元格添加组件。
花时间学习如何使用布局管理器。首先阅读 Layout Managers 上的 Swing 教程.
关于java - 以动态方式在 JScrollPane 上插入面板，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/51517713/