Java Common Constants, Enums, and Utilities
Java
Constants
java.lang.Math
- E
 - PI
 
java.net.HttpURLConnection
- HTTP_OK
 - HTTP_NO_CONTENT
 - HTTP_BAD_REQUEST
 - HTTP_UNAUTHORIZED
 - HTTP_FORBIDDEN
 - HTTP_NOT_FOUND
 - HTTP_BAD_METHOD
 - HTTP_INTERNAL_ERROR
 
javax.management.timer.Timer
- ONE_DAY
 - ONE_HOUR
 - ONE_MINUTE
 - ONE_SECOND
 - ONE_WEEK
 
Enum
java.nio.charset.StandardCharsets
- ISO_8859_1
 - UTF_8.toString()
 
Utilities
java.util
- Arrays
- asList(T… a)
 - sort(int[] a)
 - toString(Object[] a)
 
 - Collections
- emptyList()
 - emptyMap()
 - emptySet()
 - sort(List
list)  - sort(List
list, Comparator<? super T> c)  
 - Objects
- nonNull()
 - isNull(Object obj)
 - equals(Object a, Object b)
 - deepEquals(Object a, Object b)
 - compare(T a, T b, Comparator<? super T> c)
 - requireNonNull(T obj, String message)
 - toString(Object o, String nullDefault)
 
 - UUID
- randomUUID()
 
 
Others
- Optional
 - Random
 - StringJoiner
 
Java Servlet
Constants
jakarta.servlet.http.HttpServletResponse
- SC_OK
 - SC_CREATED
 - SC_NO_CONTENT
 - SC_BAD_REQUEST
 - SC_UNAUTHORIZED
 - SC_FORBIDDEN
 - SC_NOT_FOUND
 - SC_INTERNAL_SERVER_ERROR
 
Spring Framework
Constants
org.springframework.http.HttpHeaders
- ACCEPT_LANGUAGE
 - AUTHORIZATION
 - CACHE_CONTROL
 - CONTENT_DISPOSITION
 - CONTENT_TYPE
 - USER_AGENT
 
org.springframework.http.MediaType
- APPLICATION_JSON_VALUE
 - APPLICATION_FORM_URLENCODED_VALUE
 - MULTIPART_FORM_DATA_VALUE
 
Enum
org.springframework.http.HttpMethod
- GET.toString()
 - POST
 - PUT
 - DELETE
 
org.springframework.http.HttpStatus
- OK
 - NO_CONTENT
 - BAD_REQUEST
 - UNAUTHORIZED
 - FORBIDDEN
 - NOT_FOUND
 - METHOD_NOT_ALLOWED
 - INTERNAL_SERVER_ERROR
 
Utilities
org.springframework.util
- StringUtils
- hasLength(String str)
 
 - CollectionUtils
- isEmpty(Collection<?> collection)
 
 - ClassUtils
 
org.springframework.beans
- BeanUtils
- copyProperties(Object source, Object target)