Java String 轉 localdatetime yyyyMMddHHmmss 格式

import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
import org.junit.jupiter.api.Test;
import org.springframework.boot.test.context.SpringBootTest;

@SpringBootTest
public class LocalDateTimeTest {
	
	@Test
	void test() {
		String datetimestr ="20210212111022";
		DateTimeFormatter formatter= DateTimeFormatter.ofPattern("yyyyMMddHHmmss");
		LocalDateTime datetime = LocalDateTime.parse(datetimestr, formatter);
		System.out.println(datetime);
		
		DateTimeFormatter formatter2 = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
		String datetime2 = datetime.format(formatter2);
		System.out.println(datetime2);
	}

}