如何使用“dd MM”解析日期

错误示范

本示例说明如何在不指定年份的情况下解析日期，如下：


package com.fun

import com.fun.frame.SourceCode

import java.time.LocalDate
import java.time.format.DateTimeFormatter

class TSSS extends SourceCode {

    public static void main(String[] args) {
        public static void main(String[] args) {

            DateTimeFormatter formatter = DateTimeFormatter.ofPattern("dd MMM", Locale.CHINA);

            String date = "02 12";

            LocalDate localDate = LocalDate.parse(date, formatter);

            System.out.println(localDate);

            System.out.println(formatter.format(localDate));

        }

    }
}复制代码

输出

INFO-> 当前用户：fv，IP：192.168.0.100，工作目录：/Users/fv/Documents/workspace/fun/,系统编码格式:UTF-8,系统Mac OS X版本:10.15.3
Exception in thread "main" java.time.format.DateTimeParseException: Text '02 Jan' could not be parsed at index 3
    at java.time.format.DateTimeFormatter.parseResolved0(DateTimeFormatter.java:1947)
    at java.time.format.DateTimeFormatter.parse(DateTimeFormatter.java:1849)
    at java.time.LocalDate.parse(LocalDate.java:400)
    at java_time_LocalDate$parse.call(Unknown Source)
    at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:47)
    at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:115)
    at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:135)
    at com.fun.TSSS.main(TSSS.groovy:16)

Process finished with exit code 1复制代码

正解

模式dd MMM还不够；我们需要DateTimeFormatterBuilder为日期解析提供默认年份。


package com.fun

import com.fun.frame.SourceCode

import java.time.LocalDate
import java.time.format.DateTimeFormatter
import java.time.format.DateTimeFormatterBuilder
import java.time.temporal.ChronoField

class TSSS extends SourceCode {

    public static void main(String[] args) {

        DateTimeFormatter formatter = new DateTimeFormatterBuilder()
                .appendPattern("dd MM")
                .parseDefaulting(ChronoField.YEAR, 2020)
                .toFormatter(Locale.CHINA);

        String date = "02 11";

        LocalDate localDate = LocalDate.parse(date, formatter);

        System.out.println(localDate);

        System.out.println(formatter.format(localDate));

    }
}复制代码

输出

INFO-> 当前用户：fv，IP：192.168.0.100，工作目录：/Users/fv/Documents/workspace/fun/,系统编码格式:UTF-8,系统Mac OS X版本:10.15.3
2020-11-02
02 11

Process finished with exit code 0复制代码

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如何使用“dd MM”解析日期

错误示范

输出

正解

输出

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