How to define a constant (constant) in Java)

First, let's look at the example:

/** <Br/> * Method One <br/> */<br/> interface constantinterface {<br/> string Sunday = "Sunday "; <br/> string Monday = "Monday"; <br/> string Tuesday = "Tuesday"; <br/> string Wednesday = "Wednesday "; <br/> string Thursday = "Thursday"; <br/> string Friday = "Friday"; <br/> string Saturday = "Saturday "; <br/>}< br/>/** <br/> * method two <br/> */<br/> Enum constantenum {<br/> Sunday, Monday, tuesday, we Dnesday, Thursday, Friday, saturday <br/>}< br/>/** <br/> * method three <br/> */<br/> class constantclassfield {<br/> Public static final string Sunday = "Sunday "; <br/> Public static final string Monday = "Monday"; <br/> Public static final string Tuesday = "Tuesday "; <br/> Public static final string Wednesday = "Wednesday"; <br/> Public static final string Thursday = "Thursday"; <br/> Public static Final string Friday = "Friday"; <br/> Public static final string Saturday = "Saturday "; <br/>}< br/>/** <br/> * method four <br/> * http://www.ibm.com/developerworks/cn/java/l-java-interface/index.html <br/> */<br/> class constantclassfunction {<br /> Private Static final string Sunday = "Sunday "; <br/> Private Static final string Monday = "Monday"; <br/> Private Static final string Tuesday = "Tuesday "; <Br/> Private Static final string Wednesday =" Wednesday "; <br/> Private Static final string Thursday =" Thursday "; <br/> Private Static final string Friday = "Friday"; <br/> Private Static final string Saturday = "Saturday"; <br/> Public static string getsunday () {<br/> return Sunday; <br/>}< br/> Public static string getmonday () {<br/> return Monday; <br/>}< br/> Public static string gettuesday () {< Br/> return Tuesday; <br/>}< br/> Public static string getwednesday () {<br/> return Wednesday; <br/>}< br/> Public static string getthursday () {<br/> return Thursday; <br/>}< br/> Public static string getfirday () {<br/> return Friday; <br/>}< br/> Public static string getsaturday () {<br/> return Saturday; <br/>}< br/> public class testconstant {<br/> static final string day = "Saturday"; <br/> Pu BLIC static void main (string [] ARGs) {<br/> system. Out. println ("Is today Saturday? "); <Br/> system. out. println (Day. equalsignorecase (constantinterface. saturday); <br/> system. out. println (Day. equalsignorecase (constantenum. saturday. name (); <br/> system. out. println (Day. equalsignorecase (constantclassfield. saturday); <br/> system. out. println (Day. equalsignorecase (constantclassfunction <br/>. getsaturday (); <br/>}< br/>} 

Method 1 adopts the property of static final by default in the interface variable.

Method 2 uses the enum type introduced in Java 5.0.

Method 3 adopts the method of modifying variables using static final in common classes.

Method 4 is similar to method 3, but a constant is obtained through a function.

 

First, defining global variables seems to be in violation of Java's object-oriented encapsulation feature and added coupling. Therefore, the best way is to avoid defining global variables. If it is a parameter, you can write it into the configuration file. If necessary, method 2 is the most recommended. Method 3 is something that everyone can think of and is very intuitive. Method 1 and method 3 are essentially the same. Method 4 provides flexibility. For details, refer to [1 ].

 

Reference

[1] http://www.ibm.com/developerworks/cn/java/l-java-interface/index.html