public int formatFloatValueWithPrependedAndAppendedText(char[] formattedValue, float value, int
            defaultDigitsNumber, char[] label) {
        if (null != label) {
            // If custom label is not null use only name characters as formatted value.
            // Copy label into formatted value array.
            int labelLength = label.length;
            if (labelLength > formattedValue.length) {
                Log.w(TAG, "Label length is larger than buffer size(64chars), some chars will be skipped!");
                labelLength = formattedValue.length;
            }
            System.arraycopy(label, 0, formattedValue, formattedValue.length - labelLength, labelLength);
            return labelLength;
        }

        final int appliedDigitsNumber = getAppliedDecimalDigitsNumber(defaultDigitsNumber);
        final int charsNumber = formatFloatValue(formattedValue, value, appliedDigitsNumber);
        appendText(formattedValue);
        prependText(formattedValue, charsNumber);
        return charsNumber + getPrependedText().length + getAppendedText().length;
    }
Formats float value. Result is stored in (output) formattedValue array. Method
returns number of chars of formatted value. The formatted value starts at index [formattedValue.length -
charsNumber] and ends at index [formattedValue.length-1].
Note: If label is not null it will be used as formattedValue instead of float value.
Note: Parameter defaultDigitsNumber is used only if you didn't change decimalDigintsNumber value using
method {@link #setDecimalDigitsNumber(int)}.
hellocharts-library/src/lecho/lib/hellocharts/formatter/ValueFormatterHelper.java