001 package market;
002
003 /**
004 * A ValueChecker, which checks if a String is in the format of an Integer (e.g. 1500).<br>
005 * 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 VCPositiveInteger 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 VCPositiveInteger(String identifier, boolean mayBeEmpty) {
033 this.identifier = identifier;
034 this.mayBeEmpty = mayBeEmpty;
035 }
036
037 /**
038 * @param identifier the identifier.
039 */
040 public VCPositiveInteger(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 an Integer, otherwise <code>false</code>.
050 */
051 public boolean isValidValue(String content) {
052 error = 0;
053 if (!mayBeEmpty && content.equals("")) {
054 error = 1;
055 }
056 if (!content.equals("") && error == 0) {
057 try {
058 if (!content.equals("")) {
059 Integer.parseInt(content);
060 }
061 }
062 catch (NumberFormatException e) {
063 error = 2;
064 }
065 }
066 if (!content.equals("") && error == 0) {
067 if (Integer.valueOf(content).intValue() < 0) error = 3;
068 }
069 return error == 0;
070 }
071
072 /**
073 * @return an error message depending on the value of {@link #error}.
074 */
075 public String getErrorString() {
076 String returnValue = "";
077 switch (error) {
078 case 1:
079 returnValue = "Fehlerhafte Eingabe im Feld " + identifier + ": Das Feld darf nicht leer sein.";
080 break;
081 case 2:
082 returnValue = "Fehlerhafte Eingabe im Feld " + identifier + ": Es sind nur ganzzahlige Werte erlaubt.";
083 break;
084 case 3:
085 returnValue = "Fehlerhafte Eingabe im Feld " + identifier + ": Es werden positive Zahlen erwartet.";
086 break;
087 }
088 error = 0;
089 return returnValue;
090 }
091 }