When instantiating a SpreadsheetCell, its SpreadsheetCellType will specify which values the cell can accept as user input, and which SpreadsheetCellEditor it will use to receive user input.
Different static methods are provided in order to give you access to basic types, and to create SpreadsheetCell easily:

• String: Accessible with SpreadsheetCellType.StringType#createCell(int, int, int, int, String) .
• List: Accessible with SpreadsheetCellType.ListType#createCell(int, int, int, int, String).
• Double: Accessible with SpreadsheetCellType.DoubleType#createCell(int, int, int, int, Double) .
• Integer: Accessible with SpreadsheetCellType.IntegerType#createCell(int, int, int, int, Integer) .
• Date: Accessible with SpreadsheetCellType.DateType#createCell(int, int, int, int, LocalDate) .

Value verification

You can specify two levels of verification in your types.

• The first one is defined by match(Object). It is the first level that tells whether or not the given value should be accepted or not. Trying to set a String into a Double will return false for example. This method will be use by the SpreadsheetView when trying to set values for example.
  
• The second level is defined by isError(Object). This is more subtle and allow you to tell whether the given value is coherent or not regarding the policy you gave. You can just make a SpreadsheetCell call this method when its value has changed in order to react accordingly if the value is in error. (see example below).

Converter

You will have to specify a converter for your type. It will handle all the conversion between your real value type (Double, Integer, LocalDate etc) and its string representation for the cell.
You can either use a pre-built StringConverter or our StringConverterWithFormat. This one just add one method ( StringConverterWithFormat#toStringFormat(Object, String) which will convert your value with a String format (found in SpreadsheetCell#getFormat()).

Example

You can create several types which are using the same editor. Suppose you want to handle Double values. You will implement the createEditor(SpreadsheetView) method and use the SpreadsheetCellEditor.DoubleEditor.
Then for each type you will provide your own policy in match(Object) and in isError(Object), which most of the time will use your converter.
Here is an example of how to create a StringConverterWithFormat :

StringConverterWithFormat specialConverter = new StringConverterWithFormat<Double>(new DoubleStringConverter()) {
           @Override
            public String toString(Double item) {
                 //We just redirect to the other method.
                return toStringFormat(item, "");
            }

            @Override
            public String toStringFormat(Double item, String format) {
                if (item == null || Double.isNaN(item)) {
                    return missingLabel; // For example return something else that an empty cell.
                } else{
                    if (!("").equals(format) && !Double.isNaN(item)) {
                    //We format here the value
                        return new DecimalFormat(format).format(item);
                    } else {
                    //We call the DoubleStringConverter that we gave in argument
                        return myConverter.toString(item);
                    }
                }
            }

           @Override
            public Double fromString(String str) {
                if (str == null || str.isEmpty()) {
                    return Double.NaN;
                } else {
                    try {
                        //Just returning the value
                        Double myDouble = Double.parseDouble(str);
                        return myDouble;

                    } catch (NumberFormatException e) {
                        return myConverter.fromString(str);
                    }
                }
            }
        }

And then suppose you only want to accept double values between 0 and 100, and that a value superior to 10 is abnormal.

@Override
public boolean isError(Object value) {
    if (value instanceof Double) {
        if ((Double) value > 0 && (Double) value < 10) {
            return false;
        }
        return true;
    }
    return true;
}

@Override
public boolean match(Object value) {
    if (value instanceof Double) {
        return true;
    } else {
        try {
            Double convertedValue = converter.fromString(value == null ? null : value.toString());
            if (convertedValue >= 0 && convertedValue <= 100)
                return true;
            else
                return false;
        } catch (Exception e) {
            return false;
        }
    }
}