how to check if attribute has '@notNull' annotation dynamic

This solution was used in a java project with String jdbcTemplate following the idea of @NotNull JPA Annotation to check ScreenMapper from Controller and @All attributes need to have the same name column in Database.

public Boolean validationRequiredFieldsInMapper(Class<?> clazz, final Map<String, Object> screenFieldMap) {

Boolean isError = false;

Object objValue = null;

Field field = null;

String strValue = "";

for (String column : screenFieldMap.keySet()) {

field = clazz.getDeclaredField(column);

if (field != null) {

if (field.isAnnotationPresent(NotNull.class)) {

objValue = screenFieldMap.get(column);

strValue = (String) objValue;

if (StringUtils.isBlank(strValue)) {

isError = true;

break;

}

}

}

}

}

Class:

@NotNull

private Integer sap;

@NotNull

private String address;

@NotNull

private Date dateRegister;

Map: 

@RequestMapping(value="examplecontroller", method=RequestMethod.POST)

public @ResponseBody ReturnObject setData(

@RequestParam(value="sap",required= true ) String sap,

@RequestParam(value="address", required= true) String address,

@RequestParam(value="dateRegister", required= true) String dateRegister,

Map<String,Object> screenFieldMap = new HashMap<String,Object>();

screenFieldMap.put("sap",sap);

screenFieldMap.put("address",address);

screenFieldMap.put("dateRegister",dateRegister);