java - problem formatting fields in a JTable - differences between Integer and Double

Question

Update

Confirmed as a bug on JTable can't format given Object as Number when columnClass is Double (bug ID: 7051636). Feel free to vote for it, or if if you have an alternate (better) work-around, post it as a comment to the report.

---

I'm building a JTable with a custom table model built extending AbstractTableModel. My model need to support empty row to be displayed and sorted. So I follwed this post to implement that, and now works pretty fine.

I still have a problem whith formatted field in a JTable. Suppose I have the following model:

public class MyModel extends AbstractTableModel{

    public Object[] types= {new Integer(0), ""};
    public static final Object EMPTY_ROW = "";

    @Override
    public Object getValueAt(int rowIndex, int columnIndex) {
         return this.EMPTY_ROW;
    }
    public Class<? extends Object> getColumnClass(int c) {
      if (c > this.types.length - 1)
        return null;
      else
        return this.types[c].getClass();

    }
}

Everything works fine. But if I have a Double instead of an Integer:

public class MyModel extends AbstractTableModel{

        public Object[] types= {new Double(0.0), ""};
  .......

I'll get an Illegal Argument exception:

EDIT: new stack trace output after @Aaron Digulla suggestion

Exception in thread "AWT-EventQueue-0" java.lang.IllegalArgumentException: Cannot format given Object as a Number at java.text.DecimalFormat.format(DecimalFormat.java:487) at java.text.Format.format(Format.java:140) at javax.swing.JTable$DoubleRenderer.setValue(JTable.java:5352) at javax.swing.table.DefaultTableCellRenderer.getTableCellRendererComponent(DefaultTableCellRenderer.java:237) at javax.swing.JTable.prepareRenderer(JTable.java:5720) at javax.swing.plaf.basic.BasicTableUI.paintCell(BasicTableUI.java:2072) at javax.swing.plaf.basic.BasicTableUI.paintCells(BasicTableUI.java:1974) at javax.swing.plaf.basic.BasicTableUI.paint(BasicTableUI.java:1770) at javax.swing.plaf.ComponentUI.update(ComponentUI.java:143) at javax.swing.JComponent.paintComponent(JComponent.java:752) at javax.swing.JComponent.paint(JComponent.java:1029) at javax.swing.JComponent.paintChildren(JComponent.java:862) at javax.swing.JComponent.paint(JComponent.java:1038) at javax.swing.JViewport.paint(JViewport.java:747) at javax.swing.JComponent.paintChildren(JComponent.java:862) at javax.swing.JComponent.paint(JComponent.java:1038) at javax.swing.JComponent.paintChildren(JComponent.java:862) at javax.swing.JComponent.paint(JComponent.java:1038) at javax.swing.JComponent.paintChildren(JComponent.java:862) at javax.swing.JComponent.paint(JComponent.java:1038) at javax.swing.JLayeredPane.paint(JLayeredPane.java:567) at javax.swing.JComponent.paintChildren(JComponent.java:862) at javax.swing.JComponent.paintToOffscreen(JComponent.java:5131) at javax.swing.BufferStrategyPaintManager.paint(BufferStrategyPaintManager.java:278) at javax.swing.RepaintManager.paint(RepaintManager.java:1224) at javax.swing.JComponent.paint(JComponent.java:1015) at java.awt.GraphicsCallback$PaintCallback.run(GraphicsCallback.java:21) at sun.awt.SunGraphicsCallback.runOneComponent(SunGraphicsCallback.java:60) at sun.awt.SunGraphicsCallback.runComponents(SunGraphicsCallback.java:97) at java.awt.Container.paint(Container.java:1780) at java.awt.Window.paint(Window.java:3375) at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:796) at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:713) at javax.swing.RepaintManager.seqPaintDirtyRegions(RepaintManager.java:693) at javax.swing.SystemEventQueueUtilities$ComponentWorkRequest.run(SystemEventQueueUtilities.java:125) at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:209) at java.awt.EventQueue.dispatchEvent(EventQueue.java:597) at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269) at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184) at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174) at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169) at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161) at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)

Why this?

getValueAt returns always the same value to fill all tables entries with it. This is only for debug :

@Override
    public Object getValueAt(int rowIndex, int columnIndex) {
         return this.EMPTY_ROW;
    }

For example if i change to :

 @Override
    public Object getValueAt(int rowIndex, int columnIndex) {
         return new Integer(3);
         //or return new Double(3.3);
         //return new String("foobar"); doesn't work
    }

all works fine even if some field of the table are String. It suggest to me that because an Integer and a Double can be transformed into String, this won't cause problem. Anyway I would like to understand why a generic Object like my EMPTY_ROW can be accepted as value of a declared Integer field while this don't work with Double fields.

EDIT2:

If I remove getClass method in my table model. It works. Anyway I would like to solve this without having to remove that method, even if this will force me to implement some custom render methods.

EDIT3:

here's an SSCCE. There is some errors while adding new values to the table, but hasn't nothing to do with rendering problems.

import java.text.ParseException;
import java.util.ArrayList;
import java.util.Comparator;

import javax.swing.BoxLayout;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.SortOrder;
import javax.swing.RowSorter.SortKey;
import javax.swing.table.AbstractTableModel;
import javax.swing.table.TableRowSorter;


public class TableExample extends JFrame{
    public static final  Object EMPTY_ROW = "";
    public class EmptyRowComparator<COLUMN_TYPE extends Comparable<COLUMN_TYPE>> implements Comparator<Object>{//extends RuleBasedCollator{

        private TableRowSorter<? extends AbstractTableMod> sorter;
    private int column;

        public EmptyRowComparator(TableRowSorter<? extends AbstractTableMod> sorter, int col) throws ParseException {
        //  super(arg0);
            this.sorter = sorter;
            this.column = col;
            // TODO Auto-generated constructor stub
        }



         private int getSortOrder() {
             SortOrder order = SortOrder.ASCENDING;
//           List<? extends SortKey> keys = sorter.getSortKeys();
//           sorter.getSortKeys();
//       

             for (SortKey sortKey : sorter.getSortKeys()) {
                 if (sortKey.getColumn() == this.column) {
                     order = sortKey.getSortOrder();
                     break;
                 }
             }
             return order == SortOrder.ASCENDING ? 1 : -1;
         }



        @Override
        public int hashCode() {
            // TODO Auto-generated method stub
            return 0;
        }

        @Override
        public int compare(Object arg0, Object arg1) {
            // TODO Auto-generated method stub
            //System.out.println("Comparing Integer arg0 " + arg0 + " arg1 " + arg1);
            boolean empty1 = arg0 == EMPTY_ROW;
            boolean empty2 = arg1 == EMPTY_ROW;
            if (empty1 && empty2) {
                return 0;
            }
            else if (empty1) {
                return 1 * getSortOrder();
            }
            else if (empty2) {
                return -1 * getSortOrder();
            }
            return ((Comparable<COLUMN_TYPE>) (COLUMN_TYPE)arg0).compareTo((COLUMN_TYPE)arg1);
        //  return 0;
        }

    }

    public class ConcreteTable extends AbstractTableMod{

        //
        private static final long serialVersionUID = 4672561280810649603L;
        private String[] columnNames = {"ID",
                                        "description"};


        Class[] types = {Integer.class, String.class};
        //Object[] types = {Double.class, String.class};
        private int minimumDisplayedRow;


        public ConcreteTable(){
            //System.out.println("DEBUG ARRAY length " + data.length);
            this.minimumDisplayedRow = 10;
            this.datas = new ArrayList<ArrayList<Object>>();
            for (int i = 0 ; i < this.minimumDisplayedRow  ; i++){
                this.addEmptyRow();
            }
            for (int i = 0 ; i < 5 ; i++){
                ArrayList<Object> row = new ArrayList<Object>();
                row.add(new Integer(i));
                row.add(new String("prova " + i));
                this.addRow(row);
            }

        }


        public String getColumnName(int col) {
            System.out.println("getColumnName " + col + " = " + columnNames[col]);
            return columnNames[col];
        }

        @Override
        protected Class[] getTypeArray() {
            // TODO Auto-generated method stub
            return this.types;
        }

        @Override
        protected ArrayList<Integer> getKeysColumnIndex() {
            // TODO Auto-generated method stub
            ArrayList<Integer> keys = new ArrayList<Integer>();
            keys.add(0);
            return keys;
        }
        public boolean isCellEditable(int row, int col) {
            System.out.println("isCellEditable row " + row + " col " + col);
            if (col == 1){
                System.out.println("TRUE");
                return true;
            }

            return false;
        }
        /*note: generated keys must be in the same order they appear in the table*/
        @Override
        protected Object getGeneratedKeys(int col) {
            // TODO Auto-generated method stub
            if (col != 0 )
                return null;
            return new Integer(this.rowNumber);
        }
        @Override
        protected int getMinimumDisplayedRow() {
            // TODO Auto-generated method stub
            return this.minimumDisplayedRow;
        }


    }

    public abstract class AbstractTableMod extends AbstractTableModel {


        ArrayList<ArrayList<Object>> datas ;
        protected int rowNumber = 0;
        protected abstract Class[] getTypeArray();
        protected abstract ArrayList<Integer> getKeysColumnIndex();
        protected abstract Object getGeneratedKeys(int col);
        protected abstract int getMinimumDisplayedRow();

        public int getRowCount(){
            return this.datas.size() ;
        }
        @Override
        public int getColumnCount() {
            return this.getTypeArray().length;
        }

        @Override
        public Object getValueAt(int rowIndex, int columnIndex) {

            if (rowIndex >= this.rowNumber ){
                return EMPTY_ROW;
            }

            try{

                ArrayLis

Answer 1

how did Walter Laan says in his thread

Never give up! Never surrender!

EDIT: I can't resist, but due to my poor English I dare not to commenting why, where and how is that possible, nor works correctly, for confirmations I added Rob's two (little bit) modified class for TableColumnRendering ...,

import java.awt.EventQueue;
import java.math.RoundingMode;
import java.text.*;
import java.util.*;
import javax.swing.*;
import javax.swing.RowSorter.SortKey;
import javax.swing.SwingConstants;
import javax.swing.table.*;

public class TableExample extends JFrame {

    public static final Object EMPTY_ROW = "";
    private static final long serialVersionUID = 1L;
    private JTable tab;
    private Calendar cal;
    private Date dateWithOutTime = new java.util.Date();
    private SimpleDateFormat sdf = new SimpleDateFormat("dd.MM.yyyy");//standard continental EU date format

    public class EmptyRowComparator<COLUMN_TYPE extends Comparable<COLUMN_TYPE>> implements Comparator<Object> {//extends RuleBasedCollator{

        private TableRowSorter<? extends AbstractTableMod> sorter;
        private int column;

        public EmptyRowComparator(TableRowSorter<? extends AbstractTableMod> sorter, int col) throws ParseException {
            this.sorter = sorter;
            this.column = col;
        }

        private int getSortOrder() {
            SortOrder order = SortOrder.ASCENDING;
            for (SortKey sortKey : sorter.getSortKeys()) {
                if (sortKey.getColumn() == this.column) {
                    order = sortKey.getSortOrder();
                    break;
                }
            }
            return order == SortOrder.ASCENDING ? 1 : -1;
        }

        @Override
        public int hashCode() {
            return 0;
        }

        @Override
        @SuppressWarnings("unchecked")
        public int compare(Object arg0, Object arg1) {
            boolean empty1 = arg0 == EMPTY_ROW;
            boolean empty2 = arg1 == EMPTY_ROW;
            if (empty1 && empty2) {
                return 0;
            } else if (empty1) {
                return 1 * getSortOrder();
            } else if (empty2) {
                return -1 * getSortOrder();
            }
            return ((Comparable<COLUMN_TYPE>) (COLUMN_TYPE) arg0).compareTo((COLUMN_TYPE) arg1);
        }
    }

    public class ConcreteTable extends AbstractTableMod {

        private static final long serialVersionUID = 4672561280810649603L;
        private String[] columnNames = {"Integer", "String", "Integer", "Double", "Boolean", "Double", "String", "Boolean", "Date"};
        private Class<?>[] types = {Integer.class, String.class, String.class, String.class, String.class,
            String.class, String.class, String.class, String.class};
        private int minimumDisplayedRow;

        public ConcreteTable() {
            this.minimumDisplayedRow = 10;
            this.datas = new ArrayList<ArrayList<Object>>();
            for (int i = 0; i < this.minimumDisplayedRow; i++) {
                this.addEmptyRow();
            }
            Random rnd = new Random();
            for (int i = 0; i < 7; i++) {
                ArrayList<Object> row = new ArrayList<Object>();
                row.add(i);
                row.add(((rnd.nextInt(25)) + "prova"));
                row.add(rnd.nextInt(25));
                row.add(rnd.nextInt(25) + 3.14);
                row.add((i % 2 == 0) ? true : false);
                row.add(rnd.nextInt(25) + 3.14);
                row.add(((rnd.nextInt(25)) + "prova"));
                row.add((i % 2 == 0) ? false : true);
                cal = Calendar.getInstance();
                cal.add(Calendar.DATE, -rnd.nextInt(25));
                dateWithOutTime = cal.getTime();
                String nullTimeForDateString = sdf.format(dateWithOutTime);
                try {
                    dateWithOutTime = sdf.parse(nullTimeForDateString);
                } catch (ParseException ex) {
                }
                row.add(dateWithOutTime);
                this.addRow(row);

            }
        }

        @Override
        public String getColumnName(int col) {
            System.out.println("getColumnName " + col + " = " + columnNames[col]);
            return columnNames[col];
        }

        @Override
        protected Class<?>[] getTypeArray() {
            return this.types;
        }

        @Override
        protected ArrayList<Integer> getKeysColumnIndex() {
            ArrayList<Integer> keys = new ArrayList<Integer>();
            keys.add(0);
            return keys;
        }

        @Override
        public boolean isCellEditable(int row, int col) {
            System.out.println("isCellEditable row " + row + " col " + col);
            if (col == 1) {
                System.out.println("TRUE");
                return true;
            }
            return false;
        }

        @Override
        protected Object getGeneratedKeys(int col) {
            if (col != 0) {
                return null;
            }
            return new Integer(this.rowNumber);
        }

        @Override
        protected int getMinimumDisplayedRow() {
            return this.minimumDisplayedRow;
        }
    }

    public abstract class AbstractTableMod extends AbstractTableModel {

        private static final long serialVersionUID = 1L;
        protected ArrayList<ArrayList<Object>> datas;
        protected int rowNumber = 0;

        protected abstract Class<?>[] getTypeArray();

        protected abstract ArrayList<Integer> getKeysColumnIndex();

        protected abstract Object getGeneratedKeys(int col);

        protected abstract int getMinimumDisplayedRow();

        public int getRowCount() {
            return this.datas.size();
        }

        @Override
        public int getColumnCount() {
            return this.getTypeArray().length;
        }

        @Override
        public Object getValueAt(int rowIndex, int columnIndex) {
            if (rowIndex >= this.rowNumber) {
                return EMPTY_ROW;
            }
            try {
                ArrayList<Object> row = this.datas.get(rowIndex);
                if (row == null) {
                    return null;
                }
                Object obj = row.get(columnIndex);
                return obj;
            } catch (IndexOutOfBoundsException e) {
                return null;
            }
        }

        @Override
        public void setValueAt(Object value, int row, int col) {
            Class<? extends Object> targetColClass = this.getColumnClass(col);
            if (!targetColClass.isInstance(value)) {
                return;
            }

            if (value instanceof String) {
                String stringVal = (String) value;
                if (stringVal.compareTo("") == 0) {
                    return;
                }
            }
            if (row >= this.rowNumber) {
                ArrayList<Object> newRow = new ArrayList<Object>();
                ArrayList<Integer> keysIndexList = this.getKeysColumnIndex();
                for (int i = 0; i < this.getColumnCount(); i++) {
                    if (i == col) {
                        newRow.add(value);
                    } else if (keysIndexList.contains(i)) {
                        newRow.add(this.getGeneratedKeys(i));
                    } else {
                        newRow.add(EMPTY_ROW);
                    }
                }
                this.addRow(newRow);
            } else {
                this.datas.get(row).set(col, value);
            }
            this.fireTableCellUpdated(row, col);
        }

        @Override
        @SuppressWarnings("unchecked")
        public Class<? extends Object> getColumnClass(int c) {
            if (c > this.getTypeArray().length - 1) {
                return null;
            } else {
                return this.getTypeArray()[c];
            }
        }

        public void addEmptyRow() {
            ArrayList<Object> emptyRow = new ArrayList<Object>();
            for (int i = 0; i < this.getTypeArray().length; i++) {
                emptyRow.add(EMPTY_ROW);
            }
            this.datas.add(emptyRow);
        }

        public void addRow(ArrayList<Object> row) {
            Object[] types = this.getTypeArray();
            if (types.length != row.size()) {
                return;
            }
            for (int i = 0; i < row.size(); i++) {
                Class<? extends Object> targetColClass = this.getColumnClass(i);
                Object rowItem = row.get(i);
            }
            this.datas.add(this.rowNumber, row);
            this.rowNumber++;
            if (this.rowNumber < this.getMinimumDisplayedRow()) {
                this.datas.remove(this.datas.size() - 1);
            }
            this.fireTableRowsInserted(this.rowNumber, this.rowNumber);
        }
    }

    public TableExample() {
        super("JTable example");
        getContentPane().setLayout(new BoxLayout(getContentPane(), BoxLayout.Y_AXIS));
        ConcreteTable model = new ConcreteTable();
        tab = new JTable(model);
        TableRowSorter<ConcreteTable> sorter = new TableRowSorter<ConcreteTable>(model);
        try {
            sorter.setComparator(0, new EmptyRowComparator<Integer>(sorter, 0));
            sorter.setComparator(1, new EmptyRowComparator<String>(sorter, 1));
            sorter.setComparator(2, new EmptyRowComparator<String>(sorter, 2));
            sorter.setComparator(3, new EmptyRowComparator<String>(sorter, 3));
            sorter.setComparator(4, new EmptyRowComparator<String>(sorter, 4));
            sorter.setComparator(5, new EmptyRowComparator<String>(sorter, 5));
            sorter.setComparator(6, new EmptyRowComparator<String>(sorter, 6));
            sorter.setComparator(7, new EmptyRowComparator<String>(sorter, 7));
            sorter.setComparator(8, new EmptyRowComparator<String>(sorter, 8));
        } catch (ParseException e) {
            e.printStackTrace();
        }
        tab.setRowSorter(sorter);
        JScrollPane table = new JScrollPane(tab);
        this.getContentPane().add(table);
        this.setSize(800, 400);
        setDefaultCloseOperation(EXIT_ON_CLOSE);
        setRenderers();
        EventQueue.invokeLater(new Runnable() {

            @Override
            public void run() {
                setVisible(true);
            }
        });
        //TableExample tableExample = new TableExample();
    }

    public void setRenderers() {
        TableColumnModel m = tab.getColumnModel();
        //"Integer", "String", "Interger", "Double", "Boolean", "Double", "String", "Boolean", "Date"
        m.getColumn(0).setCellRenderer(NumberRenderer.getIntegerRenderer());
        m.getColumn(2).setCellRenderer(NumberRenderer.getIntegerRenderer());
        m.getColumn(3).setCellRenderer(NumberRenderer.getDoubleRenderer5());
        m.getColumn(5).setCellRenderer(NumberRenderer.getDoubleRenderer3());
        m.getColumn(8).setCellRenderer(FormatRenderer.getDateRenderer());
    }

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

            @Override
            public void run() {
                TableExample tableExample = new TableExample();
            }
        });
        TableExample tableExample = new Table