JTable Inhalte speichern

Dieses Beispiel zeigt, wie wir den Zustand einer JTable speichern können (Daten, Spaltenbreite und -position), so dass sie nach einem Programmneustart wieder geladen werden kann.

<code=java> /*

* TableSave.java
*/

import java.awt.*; import java.awt.event.*; import java.beans.*; import java.io.*; import javax.swing.*;

public class TableSave extends JFrame {

   private JTable table;
   private MyTableModel tableModel;
   private MyColumnModel columnModel;
   private String filename = "TableSaveColumns.xml";

   public TableSave() {
       super("TableSaveColumns");
       setDefaultCloseOperation(WindowConstants.DO_NOTHING_ON_CLOSE);
       setSize(400, 300);
       setLocationRelativeTo(null);
       table = new JTable();
       getContentPane().add(new JScrollPane(table), BorderLayout.CENTER);
       //TableModel:
       tableModel = new MyTableModel();
       table.setModel(tableModel);
       //ColumnModel:
       columnModel = new MyColumnModel();
       table.setColumnModel(columnModel);
       //initialize:
       tableModel.addRow(new Object[]{new Integer(101), "2a", "3a", "4a"});
       tableModel.addRow(new Object[]{new Integer(102), "2b", "3b", "4b"});
       loadTable();
       //listener:
       addWindowListener(new WindowAdapter() {

           @Override
           public void windowClosing(final WindowEvent evt) {
               saveTable();
               dispose();
           }
       });
   }

   private void saveTable() {
       try {
           XMLEncoder o = new XMLEncoder(new BufferedOutputStream(new FileOutputStream(filename)));
           o.writeObject(tableModel);
           o.writeObject(columnModel);
           o.close();
       } catch (IOException e) {
           e.printStackTrace();
       }
   }

   private boolean loadTable() {
       try {
           XMLDecoder d = new XMLDecoder(new BufferedInputStream(new FileInputStream(filename)));
           tableModel = (MyTableModel) d.readObject();
           table.setModel(tableModel);
           columnModel = (MyColumnModel) d.readObject();
           table.setColumnModel(columnModel);
           d.close();
       } catch (FileNotFoundException ex) {
           return false;
       }
       return true;
   }

   public static void main(final String args[]) {
       EventQueue.invokeLater(new Runnable() {

           public void run() {
               new TableSave().setVisible(true);
           }
       });
   }

}

</code=java>

<code=java> /*

* MyTableModel.java
* is a bean that can be saved/loaded using XMLEncoder/XMLDecoder.
* A bean must always have a default constructor (without parameters)
* and getters/setters for the attributes. It must be a "public" class.
*/

import java.util.Vector; import javax.swing.table.DefaultTableModel;

public class MyTableModel extends DefaultTableModel {

   //the default constructor is needed (there is no default constructor in DefaultTableModel):
   public MyTableModel() {
       super(0, 4);
   }

   //this setter is needed because it is missing in DefaultTableModel:
   public void setDataVector(Vector vector) {
       dataVector = vector;
   }

   //this getter is needed because it is missing in DefaultTableModel:
   public Vector getColumnIdentifiers() {
       return columnIdentifiers;
   }

   @Override
   public Class<?> getColumnClass(int columnIndex) {
       if (columnIndex == 0) {
           return Integer.class;
       }
       return String.class;
   }

} </code=java>

<code=java> /*

* MyColumnModel.java
* is a bean that can be saved/loaded using XMLEncoder/XMLDecoder
* A bean must always have a default constructor (without parameters)
* and getters/setters for the attributes. It must be a "public" class.
*/

import java.util.*; import javax.swing.table.*;

public class MyColumnModel extends DefaultTableColumnModel {

   private Object[] columnData = new Object[]{
       "Title 1", 100, //column 1: header value, width
       "Title 2", 50, //column 2: header value, width
       "Title 3", 50, //column 3: header value, width
       "Title 4", 50 //column 4: header value, width
   };

   public MyColumnModel() {
       super();
       for (int i = 0; i < columnData.length; i += 2) {
           String title = (String) columnData[i];
           Integer width = (Integer) columnData[i + 1];
           TableColumn tableColumn = new TableColumn(i / 2, width);
           tableColumn.setHeaderValue(title);
           addColumn(tableColumn);
       }
   }

   //this getter is needed because it is missing in DefaultTableColumnModel:
   public Vector<TableColumn> getTableColumns() {
       return tableColumns;
   }

   //this setter is needed because it is missing in DefaultTableColumnModel:
   public void setTableColumns(Vector<TableColumn> tableColumns) {
       this.tableColumns = tableColumns;
   }

}

</code=java>