1. 问题
2. 解答
- Java 中创建常量有 3 种方式,分别可以通过 Enum 来创建,在普通类中通过 static final 修饰变量,或者通过 Interface 来创建变量。
a. Enum 中创建常量
enum ConstantEnum {
SUNDAY, MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, SATURDAY
}
b. 在普通类中使用 static final 修饰变量
public class ConstantClassField {
public static final String SUNDAY = "SUNDAY";
public static final String MONDAY = "MONDAY";
public static final String TUESDAY = "TUESDAY";
public static final String WEDNESDAY = "WEDNESDAY";
public static final String THURSDAY = "THURSDAY";
public static final String FRIDAY = "FRIDAY";
public static final String SATURDAY = "SATURDAY";
}
c. 在 Interface 中创建常量
- 接口(Interface)中的变量默认为 static final 的特性。
public interface ConstantInterface {
String SUNDAY = "SUNDAY";
String MONDAY = "MONDAY";
String TUESDAY = "TUESDAY";
String WEDNESDAY = "WEDNESDAY";
String THURSDAY = "THURSDAY";
String FRIDAY = "FRIDAY";
String SATURDAY = "SATURDAY";
}