How to name java

1. Package names are uniformly lowercase, and there is only one English word with natural semantics between dot separators. Package names always use the singular form, but if the class name has a plural meaning, the class name can use the plural form.

Positive example: The application tool package name is com.java.util, the class name is StringUtils

2, the class name, and the interface name use UpperCamelCase style and must follow camel case, with the following exceptions ：DO/BO/DTO/VO/AO/PO/UID, etc.

Positive example:

UserLoginCheckService/UserDO

Counter example:

userlogincheckservice/UserDo

3. Method names, parameter names, member variables, and local variables all use lowerCamelCase style and must follow camel case form.

Positive example:

userServiceImpl

Counterexample:

userserviceimpl

4. Constant names are all capitalized, and words are separated by underscores. Strive to express complete and clear semantics, and do not dislike long names.

Positive example:

MAX_BOOK_COUNT/CACHE_EXPIRED_TIME

Counterexample:

MAX_COUNT/EXPIRED_TIME

5. In order to achieve the goal of self-explanation of the code, when naming any custom programming elements, use as complete a combination of words as possible To express its meaning, that is, to "see the name and know the meaning."

Positive example: In JDK, the class name that expresses atomic update is: AtomicReferenceFieldUpdater

Counterexample:

String a = "李四"; // 天啦噜，鬼知道你这个a是啥意思啊

6. When defining an array, the type is closely connected with the square brackets .

Positive example:

int[] array = new int[10];
int array[] = new int[10]; // 不建议这样写

7. The abstract class name starts with Abstract or Base; the exception class name ends with Exception; the test class name starts with the name of the class it is to test and ends with Test .

Positive example:

AbstractService/CommonException/DemoTest

8. Avoid completely non-standard abbreviations to avoid misunderstandings.

Counterexample: The "abbreviation" of AbstractClass is named AbsClass; the "abbreviation" of condition is named condi. Such arbitrary abbreviation seriously reduces the readability of the code.

9. If modules, interfaces, classes, and methods use design patterns, the specific patterns must be reflected when naming.

Note: Reflecting the design pattern in the name will help readers quickly understand the architectural design concept.

Positive example:

public class OrderFactory;
public class LoginProxy;
public class ResourceObserver;

10. For Service and DAO classes, based on the concept of SOA, the exposed service must be an interface, and the internal implementation class is distinguished from the interface by the suffix of Impl.

Positive example: CacheServiceImpl implements the CacheService interface

11. If it is an interface name that describes a capability, take the corresponding adjective as the interface name (usually the adjective of –able).

Positive example: Comparable interface in JDK

12. When assigning a value to long or Long, use an uppercase L after the value, not a lowercase l. Lowercase is easily confused with the number 1, causing misunderstanding.

Explanation: Long a = 2l; is it written as a numeric 21, or as a Long type 2? ?

13. No magic values ​​(i.e. constants that are not predefined) are allowed to appear directly in the code

Positive example:

public static final ORDER_REDIS_KEY_PREFIX = "orderId_";
String orderRedisKey = ORDER_REDIS_KEY_PREFIX + orderId;

Counter example:

String redisKey = "orderId_" + orderId;

14. The enumeration class name must be suffixed with Enum. The names of enumeration members must be in all uppercase letters and separated by underscores.

Positive example: Enumerate the member name named ProcessStatusEnum: SUCCESS / UNKNOWN_REASON

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