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POJPanel gets resized of another JPanel is shown
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  1. POJPanel gets resized of another JPanel is shown
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    copied!<p>I have a question about nested BoxLayouts.</p> <p>I want to build a DropDownPanel which consists of 2 sub-Panels: a header at the top and a body at the bottom. The body is initially hidden. By clicking on the header you can toggle the visibility of the body and show its contents (like expand/collapse).</p> <p>In general this works fine. However there is some strange behaviour:<br> If only one DropDownPanel is expanded and the other is collapsed then the collapsed DropDownPanel gets resized and floated to the right.</p> <p>I already experimented with the JPanel's properties like alignmentX, but I could not find my mistake. Does anyone know what I am doing wrong?</p> <p>Here is the code:<br> DropDownPanel.java<br></p> <pre><code>public class DropDownPanel extends javax.swing.JPanel { private boolean mShowContent = false; /** * Creates new form DropDownPanel */ public DropDownPanel() { initComponents(); showContent(mShowContent); } private void showContent(boolean showContent) { mShowContent = showContent; System.out.println(mShowContent? "show" : "hide"); body.setVisible(mShowContent); revalidate(); } /** * 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") // &lt;editor-fold defaultstate="collapsed" desc="Generated Code"&gt;//GEN-BEGIN:initComponents private void initComponents() { jPanel3 = new javax.swing.JPanel(); header = new javax.swing.JPanel(); jLabel1 = new javax.swing.JLabel(); body = new javax.swing.JPanel(); jPanel5 = new javax.swing.JPanel(); jLabel2 = new javax.swing.JLabel(); setBorder(javax.swing.BorderFactory.createLineBorder(new java.awt.Color(0, 0, 0))); setLayout(new javax.swing.BoxLayout(this, javax.swing.BoxLayout.Y_AXIS)); jPanel3.setLayout(new javax.swing.BoxLayout(jPanel3, javax.swing.BoxLayout.Y_AXIS)); header.setMaximumSize(new java.awt.Dimension(32000, 60)); header.setMinimumSize(new java.awt.Dimension(0, 60)); header.setPreferredSize(new java.awt.Dimension(0, 60)); header.addMouseListener(new java.awt.event.MouseAdapter() { public void mouseClicked(java.awt.event.MouseEvent evt) { headerMouseClicked(evt); } }); header.setLayout(new javax.swing.BoxLayout(header, javax.swing.BoxLayout.X_AXIS)); jLabel1.setText("Click Me!"); header.add(jLabel1); jPanel3.add(header); body.setLayout(new javax.swing.BoxLayout(body, javax.swing.BoxLayout.Y_AXIS)); jPanel5.setLayout(new javax.swing.BoxLayout(jPanel5, javax.swing.BoxLayout.X_AXIS)); jLabel2.setText("jLabel2"); jPanel5.add(jLabel2); body.add(jPanel5); jPanel3.add(body); add(jPanel3); }// &lt;/editor-fold&gt;//GEN-END:initComponents private void headerMouseClicked(java.awt.event.MouseEvent evt) {//GEN-FIRST:event_headerMouseClicked System.out.println("asd"); showContent(!mShowContent); }//GEN-LAST:event_headerMouseClicked // Variables declaration - do not modify//GEN-BEGIN:variables private javax.swing.JPanel body; private javax.swing.JPanel header; private javax.swing.JLabel jLabel1; private javax.swing.JLabel jLabel2; private javax.swing.JPanel jPanel3; private javax.swing.JPanel jPanel5; // End of variables declaration//GEN-END:variables } </code></pre> <p>TestFrame.java<br></p> <pre><code>public class TestFrame extends javax.swing.JFrame { /** * Creates new form TestFrame */ public TestFrame() { initComponents(); jPanel1.add(new DropDownPanel()); jPanel1.add(new DropDownPanel()); revalidate(); } /** * 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") // &lt;editor-fold defaultstate="collapsed" desc="Generated Code"&gt;//GEN-BEGIN:initComponents private void initComponents() { jScrollPane1 = new javax.swing.JScrollPane(); jPanel1 = new javax.swing.JPanel(); setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE); setMinimumSize(new java.awt.Dimension(400, 300)); jPanel1.setLayout(new javax.swing.BoxLayout(jPanel1, javax.swing.BoxLayout.Y_AXIS)); jScrollPane1.setViewportView(jPanel1); getContentPane().add(jScrollPane1, java.awt.BorderLayout.CENTER); pack(); }// &lt;/editor-fold&gt;//GEN-END:initComponents /** * @param args the command line arguments */ public static void main(String args[]) { /* * Set the Nimbus look and feel */ //&lt;editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) "&gt; /* * 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(TestFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex); } catch (InstantiationException ex) { java.util.logging.Logger.getLogger(TestFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex); } catch (IllegalAccessException ex) { java.util.logging.Logger.getLogger(TestFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex); } catch (javax.swing.UnsupportedLookAndFeelException ex) { java.util.logging.Logger.getLogger(TestFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex); } //&lt;/editor-fold&gt; /* * Create and display the form */ java.awt.EventQueue.invokeLater(new Runnable() { public void run() { new TestFrame().setVisible(true); } }); } // Variables declaration - do not modify//GEN-BEGIN:variables private javax.swing.JPanel jPanel1; private javax.swing.JScrollPane jScrollPane1; // End of variables declaration//GEN-END:variables } </code></pre>
 

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