/**
* Please feel free to experiment - not only wrong data but sometimes number format exceptions...
*/
public class SimpleDateTest {
static SimpleDateFormat df = new SimpleDateFormat("dd-MMM-yyyy");
static String testdata[] = { "01-Jan-1999", "14-Feb-2001", "31-Dec-2007" };
/**
* Test method for SDF.
*/
@Test
public void testParse() {
Runnable r[] = new Runnable[testdata.length];
for (int i = 0; i < r.length; i++) {
final int i2 = i;
r[i] = new Runnable() {
public void run() {
try {
for (int j = 0; j < 1000; j++) {
String str = testdata[i2];
String str2 = null;
// synchronized(df)
{
Date d = df.parse(str);
str2 = df.format(d);
}
Assert.assertEquals("date conversion failed after "
+ j + " iterations.", str, str2);
}
} catch (ParseException e) {
throw new RuntimeException("parse failed");
}
}
};
new Thread(r[i]).start();
}
}
}
Possible outputs are:
Exception in thread "Thread-0" junit.framework.ComparisonFailure: date conversion failed after 0 iterations. expected:<[01-Jan-1999]> but was:<[14-Feb-2001]> at junit.framework.Assert.assertEquals(Assert.java:85)
Exception in thread "Thread-0" Exception in thread "Thread-1" java.lang.NumberFormatException: For input string: "19992001.E199920014E"
Exception in thread "Thread-0" java.lang.NumberFormatException: multiple points at sun.misc.FloatingDecimal.readJavaFormatString(Unknown Source)
Exception in thread "Thread-0" java.lang.NumberFormatException: For input string: "" at java.lang.NumberFormatException.forInputString(Unknown Source)
And solution is synchronize usage of SimpleDateFormat, use ThreadLocal like here: ThreadSafeSimpleDateFormat:
tsd
or my last findings use improved version of ThreadLocal that creates HashMaps of SDF inside: SafeSimpleDateFormat
public class SafeSimpleDateFormat
{
private final String _format;
private static final ThreadLocal<Map<String, SimpleDateFormat>> _dateFormats = new ThreadLocal<Map<String, SimpleDateFormat>>()
{
public Map<String, SimpleDateFormat> initialValue()
{
return new HashMap<String, SimpleDateFormat>();
}
};
private SimpleDateFormat getDateFormat(String format)
{
Map<String, SimpleDateFormat> formatters = _dateFormats.get();
SimpleDateFormat formatter = formatters.get(format);
if (formatter == null)
{
formatter = new SimpleDateFormat(format);
formatters.put(format, formatter);
}
return formatter;
}
public SafeSimpleDateFormat(String format)
{
_format = format;
}
public String format(Date date)
{
return getDateFormat(_format).format(date);
}
public String format(Object date)
{
return getDateFormat(_format).format(date);
}
public Date parse(String day) throws ParseException
{
return getDateFormat(_format).parse(day);
}
public void setTimeZone(TimeZone tz)
{
getDateFormat(_format).setTimeZone(tz);
}
public void setCalendar(Calendar cal)
{
getDateFormat(_format).setCalendar(cal);
}
public void setNumberFormat(NumberFormat format)
{
getDateFormat(_format).setNumberFormat(format);
}
public void setLenient(boolean lenient)
{
getDateFormat(_format).setLenient(lenient);
}
public void setDateFormatSymbols(DateFormatSymbols symbols)
{
getDateFormat(_format).setDateFormatSymbols(symbols);
}
public void set2DigitYearStart(Date date)
{
getDateFormat(_format).set2DigitYearStart(date);
}
}
