error code

public static void main(String[] args)throws Exception {
    ObjectMapper objectMapper = new ObjectMapper();
    final LocalDateTime localDateTime = LocalDateTime.now();
    final String s = objectMapper.writeValueAsString(localDateTime);
    System.out.println(s);
}

Error

reason

The date was not formatted during conversion

Solution:

public static void main(String[] args)throws Exception {
    ObjectMapper objectMapper = new ObjectMapper();
    
        // Date and time formatting
        JavaTimeModule javaTimeModule = new JavaTimeModule();
        // Set the serialization format of LocalDateTime
        javaTimeModule.addSerializer(LocalDateTime.class, new LocalDateTimeSerializer(DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss")));
        javaTimeModule.addSerializer(LocalDate.class, new LocalDateSerializer(DateTimeFormatter.ofPattern("yyyy-MM-dd")));
        javaTimeModule.addSerializer(LocalTime.class, new LocalTimeSerializer(DateTimeFormatter.ofPattern("HH:mm:ss")));
        javaTimeModule.addDeserializer(LocalDateTime.class, new LocalDateTimeDeserializer(DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss")));
        javaTimeModule.addDeserializer(LocalDate.class, new LocalDateDeserializer(DateTimeFormatter.ofPattern("yyyy-MM-dd")));
        javaTimeModule.addDeserializer(LocalTime.class, new LocalTimeDeserializer(DateTimeFormatter.ofPattern("HH:mm:ss")));
        objectMapper.registerModule(javaTimeModule);

    final LocalDateTime localDateTime = LocalDateTime.now();
    final String s = objectMapper.writeValueAsString(localDateTime);
    System.out.println(s);
}