将字符串"yyyy-MM-dd"转换为LocalDateTime

Question

有什么办法转换的日期String到LocalDateTime了格式"yyyy-MM-dd"？

如果我试试这个:

DateTimeFormatter DATEFORMATTER = DateTimeFormatter.ofPattern("yyyy-MM-dd");
LocalDateTime ldt = LocalDateTime.parse(string, DATEFORMATTER);

我有这个例外:

java.time.format.DateTimeParseException: Text '2017-03-13' could not be parsed: Unable to obtain LocalDateTime from TemporalAccessor: {},ISO resolved to 2017-03-13 of type java.time.format.Parsed
    at java.time.format.DateTimeFormatter.createError(DateTimeFormatter.java:1920)
    at java.time.format.DateTimeFormatter.parse(DateTimeFormatter.java:1855)
    at java.time.LocalDateTime.parse(LocalDateTime.java:492)
    at hu.npsh.workforce.utils.Util.stringToLocalDateTime(Util.java:284)
    at hu.npsh.workforce.utils.util.StringLocalDateTimeConversionTest.stringToLocalDateTimeTest(StringLocalDateTimeConversionTest.java:35)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
    at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:86)
    at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:459)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:678)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:382)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:192)
Caused by: java.time.DateTimeException: Unable to obtain LocalDateTime from TemporalAccessor: {},ISO resolved to 2017-03-13 of type java.time.format.Parsed
    at java.time.LocalDateTime.from(LocalDateTime.java:461)
    at java.time.format.Parsed.query(Parsed.java:226)
    at java.time.format.DateTimeFormatter.parse(DateTimeFormatter.java:1851)
    ... 26 more
Caused by: java.time.DateTimeException: Unable to obtain LocalTime from TemporalAccessor: {},ISO resolved to 2017-03-13 of type java.time.format.Parsed
    at java.time.LocalTime.from(LocalTime.java:409)
    at java.time.LocalDateTime.from(LocalDateTime.java:457)
    ... 28 more

我知道主要问题,即模式不包含小时和分钟..但是如果我想创建一个方法得到一个String和一个DateTimeFormatter我想要返回的怎么办？LocalDateTime

有没有正确,好的解决方案？

编辑:

我的目标,制定一个方法得到一个String和一个DateTimeFormatter 和返回一个LocalDateTime.模式可以是任何东西(什么是有效的).

Answer 1

使用LocalDate创建LOCALDATE的,然后如果你需要它,你可以添加timepart:

    DateTimeFormatter DATEFORMATTER = DateTimeFormatter.ofPattern("yyyy-MM-dd");
    LocalDate ld = LocalDate.parse("2017-03-13", DATEFORMATTER);
    LocalDateTime ldt = LocalDateTime.of(ld, LocalDateTime.now().toLocalTime());
    System.out.println(ldt);

要么 LocalDateTime

ldt = LocalDateTime.of(ld, LocalDateTime.MIN.toLocalTime());

如果你只需要一个空的时间部分

编辑:

看看这个解决方案你可以构建你的动态解析器​​:

    DateTimeFormatter DATEFORMATTER1 = DateTimeFormatter.ofPattern("yyyy-MM-dd");

    DateTimeFormatter DATEFORMATTER = new DateTimeFormatterBuilder().append(DATEFORMATTER1)
    .parseDefaulting(ChronoField.HOUR_OF_DAY, 0)
    .parseDefaulting(ChronoField.MINUTE_OF_HOUR, 0)
    .parseDefaulting(ChronoField.SECOND_OF_MINUTE, 0)
    .toFormatter();

    //DateTimeFormatter DATEFORMATTER = DateTimeFormatter.ofPattern("yyyy-MM-dd");
    LocalDateTime ldt = LocalDateTime.parse("2017-03-13", DATEFORMATTER);

Answer 2

您无法将"2017-03-13"转换为a,LocalDateTime因为字符串中没有时间信息,只有日期.你可以将它转换为LocalDate

DateTimeFormatter dateformatter = DateTimeFormatter.ofPattern("yyyy-MM-dd");
LocalDate ld = LocalDate.parse("2017-03-13", dateformatter);

在此之后我们可以将其转换为 LocalDateTime

LocalDateTime ldt = ld.atStartOfDay();