跟王老師學枚舉（二）：使用枚舉

跟王老師學枚舉（二）：使用枚舉

主講教師：王少華   QQ羣號：483773664

一、Java枚舉

（一）、枚舉的關鍵字是enum

1 2 3

public enum Grade {   }

（二）、枚舉也是一個類

1、枚舉的構造方法，默認是私有化的

2、枚舉的實例對象，默認public static final

1 2 3

public enum Grade {     A,B,C,D,E }

3、枚舉的實例對象的變量名，必須放在所有內容之前

二、使用枚舉

（一）默認構造方法

1 2 3

public enum Grade {     A,B,C,D,E }

1 2 3 4

public class Student {     private String name;    //姓名     private Grade grade=Grade.A;    //成績：A B C D E }

1 2 3 4 5 6

public class StudentTest {     public static void main(String[] args) {         Student student = new Student();         student.setGrade(Grade.A);     } }

（二）有參數的構造方法

1 2 3 4 5 6 7 8 9 10 11

public enum Grade {     A("100-90"), B("89-80"), C("79-70"), D("69-60"), E("59-0");     private String value;       private Grade(String value) {         this.value = value;     }     public String getValue() {         return value;     } }

1 2 3 4 5 6 7 8

public class StudentTest {     public static void main(String[] args) {         Student student = new Student();         student.setGrade(Grade.A);         //輸出指定級別的分數範圍         System.out.println(Grade.B.getValue());     } }

（三）內部類

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36

public enum Grade {     A("100-90"){         public String getLocString(){             return "優";         }     },     B("89-80"){         public String getLocString(){             return "好";         }     },     C("79-70"){         public String getLocString(){             return "良";         }     },     D("69-60"){         public String getLocString(){             return "及格";         }     },     E("59-0"){         public String getLocString(){             return "不及格";         }     };     private String value;       private Grade(String value) {         this.value = value;     }     public String getValue() {         return value;     }     public abstract String getLocString(); }

1 2 3 4 5 6 7 8 9

public class StudentTest {     public static void main(String[] args) {         Student student = new Student();         student.setGrade(Grade.A);         //輸出指定級別的分數範圍         System.out.println(Grade.B.getValue());         System.out.println(Grade.C.getLocString());     } }

來自爲知筆記(Wiz)