Thread: DefaultCellEditor does not support empty cells

I have a table (MyTable) with a tablemodel and a DefaultCellEditor (see below code at the bottom). I do not want any cells in my table to be negative but empty cells are acceptable. When a user deletes the content of a cell, an error is triggered here:

if(txtfld.getText().isEmpty()==true)
return super.stopCellEditing(); //this triggers an error

What do I need to change in the code to be able to have nulls in the table?

Thanks in advance

--------------------------------------------------------

import java.awt.Color;
import java.awt.Component;
import javax.swing.*;
import javax.swing.border.*;
import javax.swing.table.*;



public class MyFrame extends javax.swing.JFrame {


public MyFrame() {
initComponents();

}

private void initComponents() {

jScrollPane1 = new javax.swing.JScrollPane();
MyTable = new javax.swing.JTable();

setDefaultCloseOperation(javax.swing.WindowConstan ts.EXIT_ON_CLOSE);
getContentPane().setLayout(new java.awt.FlowLayout());

MyTable.setModel(new MyTableModel());
MyTable.setDefaultEditor(Double.class,new TableCellNumericEditor(new javax.swing.JTextField()));
jScrollPane1.setViewportView(MyTable);

getContentPane().add(jScrollPane1);

pack();
}


public static void main(String args[]) {

java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
new MyFrame().setVisible(true);

}
});
}

private javax.swing.JTable MyTable;
private javax.swing.JScrollPane jScrollPane1;

}







class MyTableModel extends AbstractTableModel{
private String[] columnNames = {"A","B","C","D","E"};

private Object[][] data = {
{10,25.8,29.6,33.0,36.1},
{17.5,20.9,24.0,26.7,45},
};



public boolean isCellEditable(int rowIndex,
int columnIndex){
return true;
}




public Class<?> getColumnClass(int columnIndex) {

//return data[0][columnIndex].getClass();
return Double.class;
}



public int getRowCount(){
return data.length;
}


public int getColumnCount(){

return data[0].length;
}


public Object getValueAt(int row,int column){

return data[row][column];
}


public void setValueAt(Object aValue, int row, int column) {

data[row][column]=aValue;
}



public String getColumnName(int c){

return columnNames[c];

}

}


class TableCellNumericEditor extends DefaultCellEditor implements TableCellEditor {
private static final Border redcol = new LineBorder(Color.red);
private static final Border blackcol = new LineBorder(Color.black);
private JTextField txtfld;


public TableCellNumericEditor(JTextField txtfld) {
super(txtfld);
this.txtfld = txtfld;
this.txtfld.setHorizontalAlignment(JTextField.CENT ER);

}




public boolean stopCellEditing() {


if(txtfld.getText().isEmpty()==true)
return super.stopCellEditing(); //this triggers an error


try {
double vald = Double.valueOf(txtfld.getText());
if (vald < 0) {
throw new NumberFormatException();
}
} catch (NumberFormatException e) {
txtfld.setBorder(redcol);
return false;
}


return super.stopCellEditing();
}


public Component getTableCellEditorComponent(JTable table,
Object value, boolean isSelected, int row, int column) {

txtfld.setBorder(blackcol);
return super.getTableCellEditorComponent(
table, value, isSelected, row, column);
}
}

Please use code tags when posting code. Help can be found on the Announcements page.

Originally Posted by ALCOLEA1972

What do I need to change in the code to be able to have nulls in the table?

That is for you to decide.
Figure out when the null value will be introduced, how to handle it, what to display in it's place on the table as a marker. (empty space is something to show)

Originally Posted by ALCOLEA1972

I do not want any cells in my table to be negative but empty cells are acceptable.

Sometimes in systems with all positive numbers, negative values are used to represent "null" or "invalid" type values. Not that this fits into all designs, but something to consider.