How to display images in a JTable?

Question

I want to display blobs from a database into a JTable column. My code is the following:

public JTable getTable(String table,String query)throws Exception{

    JTable t1 = new JTable();

    DefaultTableModel dm = new DefaultTableModel();
    Statement st = con.createStatement();
    ResultSet rs = st.executeQuery(query);
    ResultSetMetaData rsmd = rs.getMetaData();
    int cols = rsmd.getColumnCount();
    String c[] = new String[cols];
    for(int i=0;i<cols;i++){
        c[i]=rsmd.getColumnName(i+1);
        dm.addColumn(c[i]);
    }


    //get data from rows

    Object row[]=new Object[cols];
    while(rs.next()){
        row[0] = rs.getString(1);
        row[1] = rs.getString(2);
        row[2] = rs.getString(3);
        row[3] = rs.getString(4);
        row[4] = rs.getString(5);
        row[5] = rs.getString(6);
        java.sql.Blob blob = rs.getBlob(7);
        int blobLength = (int) blob.length();
        byte[] blobAsBytes = blob.getBytes(1, blobLength);
        ImageIcon picture = new ImageIcon(blobAsBytes);

        row[6] = picture;
        row[7] = rs.getString(8);
        row[8] = rs.getString(9);

        dm.addRow(row);
    }

    t1.setModel(dm);
    con.close();
    return t1;
}

When I run this code the JTable dispays: javax.swing.ImageIcon@*numbers* instead of the image itself.

Answer 1

The DefaultTableModel displays any object as a String by calling its toString() method.

If you want to change that you have to tell the DefaultTableModel what the column's content is by overriding the getColumnClass() method.

   DefaultTableModel dm = new DefaultTableModel(){
     public class<?> getColumnClass(int columnIndex){
         return 6==columnIndex?ImageIcon.class, String.class;
     }
   };

But there is a chance that JTable does not have a DefaultRenderer for ImageIcon and still displays something unexpected. In that case you also have to set a DefaultRenderer for class ImageIcon yourself.

https://docs.oracle.com/javase/tutorial/uiswing/components/table.html

JTable Cell Renderer

Answer 2

You can add a renderer that displays an icon. Such a renderer would look like this:

public class IconCellRenderer extends DefaultTableCellRenderer {
    @Override
    public Component getTableCellRendererComponent( JTable table, Object value, boolean isSelected, boolean hasFocus, int row, int column ) {
        Component c = super.getTableCellRendererComponent( table, value, isSelected, hasFocus, row, column );
        ((JLabel) c).setIcon( (ImageIcon) value );
        ((JLabel) c).setText( "" );
        return c;
    }
}

You can add this renderer several ways:

1. Register a renderer for the ImageIcon class:

   table.setDefaultRenderer( ImageIcon.class, new IconCellRenderer( ) );
   

2. Specify a renderer for a column:

   int imageViewIndex = table.convertColumnIndexToView( 6 ); // view index of ImageIcon data
   table.getColumnModel( ).getColumn( imageViewIndex ).setRenderer( new IconCellRenderer( ) );
   

3. Subclass JTable and override getCellRenderer:

   final int imageModelIndex = 6; // model index of ImageIcon data
   JTable table = new JTable( ) {
       TableCellRenderer imageIconRenderer = new IconCellRenderer( );
       @Override
       public TableCellRenderer getCellRenderer( int row, int column ) {
           if( convertColumnIndexToModel( column ) == imageModelIndex )
               return imageIconRenderer;
           else
               return super.getCellRenderer( row, column );
       }
   };