Warum JScrollPane in JOptionPane nicht seinen gesamten Inhalt zeigt?

Question

Ich versuche, Komponenten zu einem JPanel hinzufügen, dann dieses Panel in eine JScrollPane, dann legen Sie die JScrollPane in JOptionPane.

Das Problem: nur 19 Zeile von Komponenten hinzugefügt. Es gibt eine For-Schleife, die die Anzahl der Zeilen von Komponenten bestimmt. Wenn Sie den Status-Zähler auf 19 oder weniger ändern, werden alle von ihnen angezeigt.

Dies ist ein SSCCE des Problems

import java.awt.Dimension; 
import javax.swing.GroupLayout; 
import javax.swing.JButton; 
import javax.swing.JLabel; 
import javax.swing.JOptionPane; 
import javax.swing.JPanel; 
import javax.swing.JScrollPane; 
import javax.swing.JTextField; 
import javax.swing.SwingConstants; 

public class DynamicGroupLayout extends JPanel 
{ 

    JButton addRecordButton; 
    JTextField[] FieldsArray; 
    JLabel[] LabelsArray; 
    GroupLayout layout; 
    JScrollPane scrollPane; 

    public DynamicGroupLayout() 
    { 
     addRecordButton = new JButton("add record"); 
     layout = new GroupLayout(this); 
     this.setLayout(layout); 
     layout.setAutoCreateGaps(true); 
     layout.setAutoCreateContainerGaps(true); 

     scrollPane = new JScrollPane(this); 
     scrollPane.getVerticalScrollBar().setUnitIncrement(16); 
     scrollPane.setPreferredSize(this.getPreferredSize()); 

     setTextFields(); 
     showDialog(); 
    } 

    @Override 
    public Dimension getPreferredSize() 
    { 
     return new Dimension(400, 500); 
    } 

    private void setTextFields() 
    { 
     int num = 30; //If 19 or less, all components shown. 
     String[] labelsNames = 
     { 
      "1", "2", "3", "4", "5", "6", "7", "8", "9", "10", 
      "11", "12", "13", "14", "15", "16", "17", "18", "19", "20", 
      "21", "22", "23", "24", "25", "26", "27", "28", "29", "30" 
     }; 
     FieldsArray = new JTextField[num]; 
     LabelsArray = new JLabel[num]; 

     GroupLayout.ParallelGroup parallelGroupHoriz = layout.createParallelGroup(); 
     layout.setHorizontalGroup(layout.createSequentialGroup().addGroup(parallelGroupHoriz)); 
     for (int i = 0; i < num; i++) 
     { 
      System.out.println(i); 
      LabelsArray[i] = new JLabel(labelsNames[i]); 
      FieldsArray[i] = new JTextField(10); 
      FieldsArray[i].setMaximumSize(new Dimension(200, 3)); 
      LabelsArray[i].setLabelFor(FieldsArray[i]); 
      parallelGroupHoriz.addGroup(layout.createSequentialGroup() 
        .addComponent(LabelsArray[i]) 
        .addComponent(FieldsArray[i])); 
     } 
     parallelGroupHoriz.addComponent(addRecordButton, GroupLayout.Alignment.CENTER); 

     GroupLayout.SequentialGroup sequentialGroupVert = layout.createSequentialGroup(); 

     layout.setVerticalGroup(sequentialGroupVert); 
     for (int i = 0; i < num; i++) 
     { 
      sequentialGroupVert.addGroup(layout.createParallelGroup(). 
        addComponent(LabelsArray[i]) 
        .addComponent(FieldsArray[i])); 
     } 
     sequentialGroupVert.addComponent(addRecordButton); 

     for (int i = 0; i < num; i++) 
     { 
      layout.linkSize(SwingConstants.HORIZONTAL, LabelsArray[i], LabelsArray[0]); 
     } 
    } 

    private void showDialog() 
    { 
     JOptionPane.showOptionDialog(null, scrollPane, "Update data", 
       JOptionPane.DEFAULT_OPTION, JOptionPane.PLAIN_MESSAGE, null, 
       null, null); 
    } 

    public static void main(String[] args) 
    { 
     DynamicGroupLayout d = new DynamicGroupLayout(); 
    } 
} 

Answer 1

Wie in dieser verwandten example gezeigt, können Sie die bevorzugte Größe des Ansichtsfenster außer Kraft setzen.

import java.awt.Dimension; 
import java.awt.EventQueue; 
import javax.swing.GroupLayout; 
import javax.swing.JLabel; 
import javax.swing.JOptionPane; 
import javax.swing.JPanel; 
import javax.swing.JScrollPane; 
import javax.swing.JTextField; 
import javax.swing.SwingConstants; 

/** 
* @see https://stackoverflow.com/a/14858272/230513 
* @see https://stackoverflow.com/a/8504753/230513 
* @see https://stackoverflow.com/a/14011536/230513 
*/ 
public class DynamicGroupLayout { 

    private static final int NUM = 30; 
    private JTextField[] fields = new JTextField[NUM]; 
    private JLabel[] labels = new JLabel[NUM]; 

    private JPanel create() { 
     JPanel panel = new JPanel(); 
     GroupLayout layout = new GroupLayout(panel); 
     panel.setLayout(layout); 
     layout.setAutoCreateGaps(true); 
     layout.setAutoCreateContainerGaps(true); 
     GroupLayout.ParallelGroup parallel = layout.createParallelGroup(); 
     layout.setHorizontalGroup(layout.createSequentialGroup().addGroup(parallel)); 
     GroupLayout.SequentialGroup sequential = layout.createSequentialGroup(); 
     layout.setVerticalGroup(sequential); 
     for (int i = 0; i < NUM; i++) { 
      labels[i] = new JLabel(String.valueOf(i + 1), JLabel.RIGHT); 
      fields[i] = new JTextField(String.valueOf("String " + (i + 1))); 
      labels[i].setLabelFor(fields[i]); 
      parallel.addGroup(layout.createSequentialGroup(). 
       addComponent(labels[i]).addComponent(fields[i])); 
      sequential.addGroup(layout.createParallelGroup(GroupLayout.Alignment.BASELINE). 
       addComponent(labels[i]).addComponent(fields[i])); 
      layout.linkSize(SwingConstants.HORIZONTAL, labels[i], labels[0]); 
     } 
     return panel; 
    } 

    public static void main(String[] args) { 
     EventQueue.invokeLater(new Runnable() { 
      @Override 
      public void run() { 
       final JPanel panel = new DynamicGroupLayout().create(); 
       JScrollPane jsp = new JScrollPane(panel) { 
        @Override 
        public Dimension getPreferredSize() { 
         return new Dimension(320, 240); 
        } 
       }; 
       JOptionPane.showMessageDialog(null, 
        jsp, "Data", JOptionPane.PLAIN_MESSAGE); 
      } 
     }); 
    } 
}