下面的代码是java.util.Date中的一个方法,在Date(String s)的构造中被调用,我不明白syntax:{}这种用法是什么意思?望各位不吝赐教,谢谢.
@Deprecated
public static long parse(String s) {
int year = Integer.MIN_VALUE;
int mon = -1;
int mday = -1;
int hour = -1;
int min = -1;
int sec = -1;
int millis = -1;
int c = -1;
int i = 0;
int n = -1;
int wst = -1;
int tzoffset = -1;
int prevc = 0;
syntax:
{
if (s == null)
break syntax;
int limit = s.length();
while (i < limit) {
c = s.charAt(i);
i++;
if (c <= ' ' || c == ',')
continue;
if (c == '(') { // skip comments
int depth = 1;
while (i < limit) {
c = s.charAt(i);
i++;
if (c == '(') depth++;
else if (c == ')')
if (--depth <= 0)
break;
}
continue;
}
if ('0' <= c && c <= '9') {
n = c - '0';
while (i < limit && '0' <= (c = s.charAt(i)) && c <= '9') {
n = n * 10 + c - '0';
i++;
}
if (prevc == '+' || prevc == '-' && year != Integer.MIN_VALUE) {
// timezone offset
if (n < 24)
n = n * 60; // EG. "GMT-3"
else
n = n % 100 + n / 100 * 60; // eg "GMT-0430"
if (prevc == '+') // plus means east of GMT
n = -n;
if (tzoffset != 0 && tzoffset != -1)
break syntax;
tzoffset = n;
} else if (n >= 70)
if (year != Integer.MIN_VALUE)
break syntax;
else if (c <= ' ' || c == ',' || c == '/' || i >= limit)
// year = n < 1900 ? n : n - 1900;
year = n;
else
break syntax;
else if (c == ':')
if (hour < 0)
hour = (byte) n;
else if (min < 0)
min = (byte) n;
else
break syntax;
else if (c == '/')
if (mon < 0)
mon = (byte) (n - 1);
else if (mday < 0)
mday = (byte) n;
else
break syntax;
else if (i < limit && c != ',' && c > ' ' && c != '-')
break syntax;
else if (hour >= 0 && min < 0)
min = (byte) n;
else if (min >= 0 && sec < 0)
sec = (byte) n;
else if (mday < 0)
mday = (byte) n;
// Handle two-digit years < 70 (70-99 handled above).
else if (year == Integer.MIN_VALUE && mon >= 0 && mday >= 0)
year = n;
else
break syntax;
prevc = 0;
} else if (c == '/' || c == ':' || c == '+' || c == '-')
prevc = c;
else {
int st = i - 1;
while (i < limit) {
c = s.charAt(i);
if (!('A' <= c && c <= 'Z' || 'a' <= c && c <= 'z'))
break;
i++;
}
if (i <= st + 1)
break syntax;
int k;
for (k = wtb.length; --k >= 0;)
if (wtb[k].regionMatches(true, 0, s, st, i - st)) {
int action = ttb[k];
if (action != 0) {
if (action == 1) { // pm
if (hour > 12 || hour < 1)
break syntax;
else if (hour < 12)
hour += 12;
} else if (action == 14) { // am
if (hour > 12 || hour < 1)
break syntax;
else if (hour == 12)
hour = 0;
} else if (action <= 13) { // month!
if (mon < 0)
mon = (byte) (action - 2);
else
break syntax;
} else {
tzoffset = action - 10000;
}
}
break;
}
if (k < 0)
break syntax;
prevc = 0;
}
}
if (year == Integer.MIN_VALUE || mon < 0 || mday < 0)
break syntax;
// Parse 2-digit years within the correct default century.
if (year < 100) {
synchronized (Date.class) {
if (defaultCenturyStart == 0) {
defaultCenturyStart = gcal.getCalendarDate().getYear() - 80;
}
}
year += (defaultCenturyStart / 100) * 100;
if (year < defaultCenturyStart) year += 100;
}
if (sec < 0)
sec = 0;
if (min < 0)
min = 0;
if (hour < 0)
hour = 0;
BaseCalendar cal = getCalendarSystem(year);
if (tzoffset == -1) { // no time zone specified, have to use local
BaseCalendar.Date ldate = (BaseCalendar.Date) cal.newCalendarDate(TimeZone.getDefaultRef());
ldate.setDate(year, mon + 1, mday);
ldate.setTimeOfDay(hour, min, sec, 0);
return cal.getTime(ldate);
}
BaseCalendar.Date udate = (BaseCalendar.Date) cal.newCalendarDate(null); // no time zone
udate.setDate(year, mon + 1, mday);
udate.setTimeOfDay(hour, min, sec, 0);
return cal.getTime(udate) + tzoffset * (60 * 1000);
}
// syntax error
throw new IllegalArgumentException();
}
------解决思路----------------------
Syntax在这里是定义标签，{}是代码块，便于在程序中使用break
------解决思路----------------------
自定义标签，方便从深层次的循环中跳出循环。
break syntax; // 跳出循环到给定的标签处。
------解决思路----------------------
标签，给break用的