Java 8 – How to parse date with LocalDateTime
Here are a few Java 8 examples to parse date with LocalDateTime
.
First, find the DateTimeFormatter
pattern that matches the date format, for example:
String str = "2020-01-30 12:30:41";
DateTimeFormatter dtf = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
second, parse it with LocalDateTime.parse
DateTimeFormatter dtf = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
String str = "2020-01-30 12:30:41";
LocalDateTime localDateTime = LocalDateTime.parse(str, dtf);
1. 2020-01-30 12:30:41
JavaDateTimeExample1.java
package com.mkyong.time;
import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
public class JavaDateTimeExample1 {
public static void main(String[] args) {
String str = "2020-01-30 12:30:41";
DateTimeFormatter dtf = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
// String -> LocalDateTime
LocalDateTime localDateTime = LocalDateTime.parse(str, dtf);
// LocalDateTime -> String
String result = localDateTime.format(dtf);
System.out.println(result);
}
}
Output
2020-01-30 12:30:41
2. 31-Aug-2020
2.1 By default, DateTimeFormatter
will use the default JVM locale to parse the date. In this example, the -Aug-
is an English word, if the JVM default locale is US, everything is fine.
JavaDateTimeExample2.java
package com.mkyong.time;
import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
public class JavaDateTimeExample2 {
public static void main(String[] args) {
// default jvm locale
System.out.println(Locale.getDefault()); //en_US
String str = "31-Aug-2020";
DateTimeFormatter dtf = DateTimeFormatter.ofPattern("d-MMM-yyyy");
// String -> LocalDateTime
LocalDateTime localDateTime = LocalDate.parse(str, dtf).atStartOfDay();
// LocalDateTime -> String
String result = localDateTime.format(dtf);
System.out.println(result);
}
}
Output
en_US
31-Aug-2020
2.2 Now the DateTimeParseException
will be thrown if we change the JVM default locale to CHINA
.
Locale.setDefault(Locale.CHINA);
String str = "31-Aug-2020";
DateTimeFormatter dtf = DateTimeFormatter.ofPattern("d-MMM-yyyy");
LocalDateTime localDateTime = LocalDate.parse(str, dtf).atStartOfDay();
Output
Exception in thread "main" java.time.format.DateTimeParseException: Text '31-Aug-2020' could not be parsed at index 3
at java.base/java.time.format.DateTimeFormatter.parseResolved0(DateTimeFormatter.java:2046)
at java.base/java.time.format.DateTimeFormatter.parse(DateTimeFormatter.java:1948)
at java.base/java.time.LocalDate.parse(LocalDate.java:428)
To solve it, defined the correct locale in DateTimeFormatter
.
JavaDateTimeExample3.java
package com.mkyong.time;
import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
import java.util.Locale;
public class JavaDateTimeExample3 {
public static void main(String[] args) {
Locale.setDefault(Locale.CHINA);
String str = "31-Aug-2020";
// don't care about the JVM default locale, we use Locale.US to parse date
DateTimeFormatter dtf = DateTimeFormatter.ofPattern("d-MMM-yyyy", Locale.US);
// String -> LocalDateTime
LocalDateTime localDateTime = LocalDate.parse(str, dtf).atStartOfDay();
// LocalDateTime -> String
String result = localDateTime.format(dtf);
System.out.println(result);
}
}
Output
31-Aug-2020
References
About Author
Comments
Subscribe
0 Comments