Android @IntDef的使用 - 代替枚举

Android @IntDef的使用 - 代替枚举

官方文档说明，安卓开发应避免使用Enum（枚举类），因为相比于静态常量Enum会花费两倍以上的内存。[ 参考 ]
那么如果需要使用Enum应该怎么做呢？

public class MainActivity extends Activity {
 
    //先定义 常量
    public static final int SUNDAY = 0;
    public static final int MONDAY = 1;
    public static final int TUESDAY = 2;
    public static final int WEDNESDAY = 3;
    public static final int THURSDAY = 4;
    public static final int FRIDAY = 5;
    public static final int SATURDAY = 6;
 
    //用 @IntDef "包住" 常量；
    // @Retention 定义策略
    // 声明构造器
    @IntDef({SUNDAY, MONDAY,TUESDAY,WEDNESDAY,THURSDAY,FRIDAY,SATURDAY})
    @Retention()
    public @interface WeekDays {}
 
    @WeekDays int currentDay = SUNDAY;
 
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        (savedInstanceState);
        setContentView(.activity_main);
        setCurrentDay(WEDNESDAY);
 
        //声明变量
        @WeekDays int today = getCurrentDay();
 
        switch (today){
            case SUNDAY:
                break;
            case MONDAY:
                break;
            case TUESDAY:
                break;
            case WEDNESDAY:
                break;
            case THURSDAY:
                break;
            case FRIDAY:
                break;
            case SATURDAY:
                break;
            default:
                break;
        }
 
    }
 
    public void setCurrentDay(@WeekDays int currentDay) {
         = currentDay;
    }
 
    @WeekDays
    public int getCurrentDay() {
        return currentDay;
    }
}

如果缺少依赖，在中增加如下依赖

compile ‘:support-annotations:22.0.0‘

String类型

string类型和int类型类似，使用@StringDef即可

@StringDef({, , , })
@Retention()
public @interface DepositStatus {
    String PAID = "PAID"; 
    String UNPAID = "UNPAID";
    String FREE = "FREE"; 
    String EXPIRE = "EXPIRE"; 
}

转载自/