import javax.swing.table.*;
//import com.sun.java.swing.table.*;

public class ExtendedTableModel extends DefaultTableModel {
  
  
  ExtendedTableModel(String[] n, int i) {
    super(n,i);
  }
  
 
  public Class getColumnClass(int c) {
    Double d = new Double(0);
    return d.getClass();
  }
  
  
  public void setColumnName(int column, String newName) {
    columnIdentifiers.removeElementAt(column);
    columnIdentifiers.insertElementAt(newName,column);
    fireTableStructureChanged();
  }
  
  // this method assumes that the table is initialized with 
  // two columns, "A" and "B".  It is safe to use until you have 
  // more than 52 columns (the alphabet twice) 
  public void addNextLetteredColumn()
  {
    char columnChar = (char)(64+getColumnCount()+1);
    if((char)(64+getColumnCount()+1) > 'Z') {      
      columnChar = (char)((64+getColumnCount())-((int)'Z'-(int)'A'));
      addColumn(getUniqueString("" + columnChar + "" + columnChar));
    }
    else
      addColumn(getUniqueString("" + columnChar));
  }

  public String getUniqueString(String string)
  {  
    for(int i = 0; i < getColumnCount(); i++)
    {
      if(string.equals(getColumnName(i))) {
        string = "~" + string + "~";
      }
    }
    return string;
  }
}