Question

如何在Java 5中使用这行代码，因为此代码使用threetenbp与Java 6和7一起运行，并直接在Java 8上运行：

// start date (set the time to start of day)
ZonedDateTime from = LocalDate.parse("2017-07-05").atStartOfDay(ZoneOffset.UTC);
// end date (set the time to 11 PM)
ZonedDateTime to = LocalDate.parse("2017-07-08").atTime(23, 0).atZone(ZoneOffset.UTC);

// get start and end timestamps
long start = from.toInstant().truncatedTo(ChronoUnit.MINUTES).toEpochMilli() / 1000;
long end = to.toInstant().truncatedTo(ChronoUnit.MINUTES).toEpochMilli() / 1000;

Answer 1

ThreeTen Backport似乎仅适用于Java 6和7.我已经使用JDK 5进行了测试，并抛出import UIKit class VC: UIViewController { @IBOutlet weak var usernameTxt: UITextField! @IBOutlet weak var emailTxt: UITextField! @IBOutlet weak var passTxt: UITextField! override func viewDidLoad() { super.viewDidLoad() setupView() } func setupView() { usernameTxt.attributedPlaceholder = NSAttributedString(string: "username", attributes: [NSAttributedStringKey.foregroundColor: smackPurplePlaceholder]) emailTxt.attributedPlaceholder = NSAttributedString(string: "email", attributes: [NSAttributedStringKey.foregroundColor: smackPurplePlaceholder]) passTxt.attributedPlaceholder = NSAttributedString(string: "password", attributes: [NSAttributedStringKey.foregroundColor: smackPurplePlaceholder]) } }。

在Java 5中，一种替代方法是旧的UnsupportedClassVersionError和SimpleDateFormat类：

Calendar

另一种方法是使用Joda-Time，其API与// set the formatter to UTC TimeZone utc = TimeZone.getTimeZone("UTC"); SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd"); sdf.setTimeZone(utc); // parse and set the time to midnight Calendar cFrom = Calendar.getInstance(utc); cFrom.setTime(sdf.parse("2017-07-05")); cFrom.set(Calendar.HOUR_OF_DAY, 0); cFrom.set(Calendar.MINUTE, 0); cFrom.set(Calendar.SECOND, 0); cFrom.set(Calendar.MILLISECOND, 0); // parse and set the time to 23:00 Calendar cTo = Calendar.getInstance(utc); cTo.setTime(sdf.parse("2017-07-08")); cTo.set(Calendar.HOUR_OF_DAY, 23); cTo.set(Calendar.MINUTE, 0); cTo.set(Calendar.SECOND, 0); cTo.set(Calendar.MILLISECOND, 0); // get the epoch second (get millis and divide by 1000) long start = cFrom.getTimeInMillis() / 1000; long end = cTo.getTimeInMillis() / 1000;非常相似：

java.time

这将为import org.joda.time.DateTime; import org.joda.time.DateTimeZone; import org.joda.time.LocalDate; import org.joda.time.LocalTime; DateTime from = LocalDate.parse("2017-07-05").toDateTimeAtStartOfDay(DateTimeZone.UTC); DateTime to = LocalDate.parse("2017-07-08").toDateTime(new LocalTime(23, 0), DateTimeZone.UTC); long start = from.getMillis() / 1000; long end = to.getMillis() / 1000;和start生成相同的值。

请注意：Joda-Time处于维护模式，正在被新的API取代，所以我不建议用它来开始一个新项目（除非你不能使用新的API＆＃ 39; s，当然）。
即使在joda's website它也说：＆＃34;请注意，Joda-Time被认为是一个很大程度上“完成”的项目。没有计划重大改进。如果使用Java SE 8，请迁移到java.time（JSR-310）。＆＃34; 。

将java.time类从java 8转换为java 5

1 个答案: