java在Android中更改日期格式

Question

我是Android和Java开发的新手

我有这一天的类型"Fri Jan 27 00:00:00 GMT+00:00 1995"<；——（输入）

我想得到"1995/27/01"<；-（产出）

我使用的代码是：

String inputPattern = "EEE MMM dd HH:mm:ss z yyyy";
String outputPattern = "yyyy-MM-dd";

SimpleDateFormat inputFormat = new SimpleDateFormat(inputPattern);
SimpleDateFormat outputFormat = new SimpleDateFormat(outputPattern);

Date date = inputFormat.parse("Fri Jan 27 00:00:00 GMT+00:00 1995");
String str = outputFormat.format(date);

但我得到了一个ParseException

知道为什么吗

Answer 1

如果使用java.time（可从Java 8获得），可以这样做：

public static void main(String[] args) {
    // example input String
    String datetime = "Fri Jan 27 00:00:00 GMT+00:00 1995";
    // define a pattern that parses the format of the input String
    String inputPattern = "EEE MMM dd HH:mm:ss O uuuu";
    // define a formatter that uses this pattern for parsing the input
    DateTimeFormatter parser = DateTimeFormatter.ofPattern(inputPattern, Locale.ENGLISH);
    // use the formatter in order to parse a zone-aware object
    ZonedDateTime zdt = ZonedDateTime.parse(datetime, parser);
    // then output it in the built-in ISO format once,
    System.out.println("date, time and zone (ISO):\t"
                        + zdt.format(DateTimeFormatter.ISO_ZONED_DATE_TIME));
    // then extract the date part
    LocalDate dateOnly = zdt.toLocalDate();
    // and output that date part using a formatter with a date-only pattern
    System.out.println("date only as desired:\t\t"
                        + dateOnly.format(DateTimeFormatter.ofPattern("uuuu/dd/MM")));
}

这段代码的输出是

date, time and zone (ISO):  1995-01-27T00:00:00Z
date only as desired:       1995/27/01

Answer 2

可能会在代码中添加applyPattern函数

String inputPattern = "EEE MMM dd HH:mm:ss z yyyy";
String outputPattern = "yyyy-MM-dd";

SimpleDateFormat sdf = new SimpleDateFormat(inputPattern);
Date date = sdf.parse("Fri Jan 27 00:00:00 GMT+00:00 1995");

sdf.applyPattern(outputPattern);
String str = sdf.format(date);