String input = "John Doe at:2016-01-16 Notes:This is a test";
String regex = " at:(\\d{4}-\\d{2}-\\d{2}) Notes:";
Matcher m = Pattern.compile(regex).matcher(input);
if (m.find()) {
Date date = new SimpleDateFormat("yyyy-MM-dd").parse(m.group(1));
// Use date here
} else {
// Bad input
}
或在Java 8+中:
LocalDate date = LocalDate.parse(m.group(1));
<dependency>
<groupId>net.rationalminds</groupId>
<artifactId>DateParser</artifactId>
<version>0.3.0</version>
</dependency>
import java.util.List;
import net.rationalminds.LocalDateModel;
import net.rationalminds.Parser;
public class Test {
public static void main(String[] args) throws Exception {
Parser parser=new Parser();
List<LocalDateModel> dates=parser.parse("Identified date :'2015-January-10 18:00:01.704', converted");
System.out.println(dates);
}
}
输出结果：[LocalDateModel{originalText=2015-january-10 18:00:01.704, dateTimeString=2015-1-10 18:00:01.704, conDateFormat=yyyy-MM-dd HH:mm:ss.SSS, start=18, end=46}]
详细博客请参考http://coffeefromme.blogspot.com/2015/10/how-to-extract-date-object-from-given.html
完整代码可在GitHub上找到：https://github.com/vbhavsingh/DateParser
：
String fromDate = "2009/05/19";
DateFormat df = new SimpleDateFormat("yyyy/MM/dd");
java.util.Date dtt = df.parse(fromDate);
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class StringInBetween {
public static void main(String[] args) throws ParseException {
//"name+" at:"+Date+" Notes:"+meetingnotes" (name, Date and meetingnotes being variables).
String test = "rama"+ " at:"+"2015-01-02"+" Notes:"+"meetingnotes";
Pattern pattern = Pattern.compile("at:(.*)Notes");
Matcher matcher = pattern.matcher(test);
if(matcher.find())
{
String dateString = matcher.group(1); //I'm using the Capturing groups to capture only the value.
java.util.Date date = new SimpleDateFormat("yyyy-mm-dd").parse(dateString);
System.out.println(date);
}
}
}
对于初学者而言，使用正则表达式可能有点过于复杂。
一个简单但是低技术的方法是搜索你所需文本所包含的两个已知部分：at:和Notes:。
假设你确信这两个文本片段不会在其他文本中出现，你可以分别搜索它们并了解它们在整个字符串中的位置。使用String::indexOf来获得这些位置。然后使用String::substring`来提取表示日期值的文本。
String input = "John Doe at:2016-01-16 Notes:This is a test";
String at = "at:"; // We expect these two pieces of text to be embedded.
String notes = " Notes:";
// Verify that our expected pieces of text are indeed embedded.
if ( ! ( input.contains ( at ) && input.contains ( notes ) ) ) {
// …handle error…
System.out.println ( "ERROR - unexpected input" );
return;
}
int indexAt = input.indexOf ( at );
int indexNotes = input.indexOf ( notes );
String extracted = input.substring ( indexAt + at.length ( ), indexNotes );
LocalDate将提取的文本解析以获取LocalDate对象。已经多次介绍了将字符串解析为日期时间的方法，请搜索StackOverflow以了解更多信息。
您指定的格式yyyy-MM-dd符合标准ISO 8601格式。当解析/生成字符串时，java.time类默认使用这些标准格式。
LocalDate localDate = LocalDate.parse ( extracted );
System.out.println ( "extracted: " + extracted );
System.out.println ( "localDate.toString(): " + localDate );