move helper classes up to more general libs

Author: thsc42

src/net/sharksystem/asap/util/DateTimeHelper.java

@@ -0,0 +1,15 @@
+package net.sharksystem.asap.util;
+
+import java.text.DateFormat;
+import java.util.Date;
+
+public class DateTimeHelper {
+    public static final long TIME_NOT_SET = -1;
+
+    public static String long2DateString(long longtime) {
+        if(longtime == TIME_NOT_SET) return "not set (yet)";
+
+        Date date = new Date(longtime);
+        return DateFormat.getInstance().format(date);
+    }
+}