001    package market;
002    
003    /**
004     * A ValueChecker, which checks if a String is in the format of a Double (e.g. 15.256).<br>
005     * Notations like 15,256 are also allowed. The number must not be negative.<br>
006     * <br>
007     * As this ValueChecker is only used by {@link market.swing.JTFCheckable checkable text fields},
008     * an identifier is passed via the constructor. This descriptive identifier is used in the error string,
009     * to enable the user to associate an error message with the causative text field.
010     */
011    public class VCPositiveDouble implements ValueChecker {
012    
013        /**
014         * The identifier used by {@link #getErrorString()}.
015         */
016        protected String identifier;
017    
018        /**
019         * Defines if an empty String is considered to be an error or not.
020         */
021        protected boolean mayBeEmpty;
022    
023        /**
024         * Internal error code. Set by {@link #isValidValue(String)}, queried by {@link #getErrorString()}.
025         */
026        private int error;
027    
028        /**
029         * @param identifier the identifier.
030         * @param mayBeEmpty <code>true</code> if an empty should be considered valid, otherwise <code>false</code>.
031         */
032        public VCPositiveDouble(String identifier, boolean mayBeEmpty) {
033            this.identifier = identifier;
034            this.mayBeEmpty = mayBeEmpty;
035        }
036    
037        /**
038         * @param identifier the identifier.
039         */
040        public VCPositiveDouble(String identifier) {
041            this.identifier = identifier;
042            this.mayBeEmpty = false;
043        }
044    
045        /**
046         * Checks String for validity and, if necessary, sets an internal error code according to the
047         * detected error.
048         * @param content the String to be checked.
049         * @return <code>true</code> if the String represents a Double, otherwise <code>false</code>.
050         */
051        public boolean isValidValue(String content) {
052            error = 0;
053            if (!mayBeEmpty && content.equals("")) error = 1;
054            if (!content.equals("") && error == 0) {
055                if (Conversions.convertComma(content) == null) error = 2;
056            }
057            if (!content.equals("") && error == 0) {
058                if (Double.valueOf(Conversions.convertComma(content)).doubleValue() < 0) error = 3;
059            }
060            return error == 0;
061        }
062    
063        /**
064         * @return an error message depending on the value of {@link #error}.
065         */
066        public String getErrorString() {
067            String returnValue = "";
068            switch (error) {
069                case 1:  returnValue =  "Fehlerhafte Eingabe im Feld " + identifier + ": Das Feld darf nicht leer sein."; break;
070                case 2:  returnValue = "Fehlerhafte Eingabe im Feld " + identifier + ": Es werden Kommazahlen erwartet."; break;
071                case 3:  returnValue = "Fehlerhafte Eingabe im Feld " + identifier + ": Es werden positive Zahlen erwartet."; break;
072            }
073            error = 0;
074            return returnValue;
075        }
076    }