在JDK1.5引入了新的類型——枚舉,存放在 java.lang 包中。
下面是我在使用 enum 過程中的一些代碼
package com.test;
// 枚舉用於存放同一類型的參數
public enum TestWeekEnum {
Monday(1, "星期一"), Tuesday(2, "星期二"), Wednesday(3, "星期三"), Thursday(4, "星期四"), Friday(5, "星期五"), Saturday(
6, "星期六"), Sunday(7, "星期天");
int code;// 參數值
String destription;// 參數說明
TestWeekEnum(int code, String destription) {
this.code = code;
this.destription = destription;
}
// 判斷傳入code在枚舉中是否存在
public boolean eqlues(TestWeekEnum type, int code) {
return code == type.code;
}
// 根據傳入code返回相應的枚舉類型
public static TestWeekEnum getDiscountType(int code) {
for (TestWeekEnum valuesEnum : TestWeekEnum.values()){
if (code == valuesEnum.getCode()){
return valuesEnum;
}
}
return null;
}
public int getCode() {
return code;
}
public void setCode(int code) {
this.code = code;
}
public String getDestription() {
return destription;
}
public void setDestription(String destription) {
this.destription = destription;
}
public static void main(String[] args) {
System.out.println(TestWeekEnum.Monday.code);
System.out.println(TestWeekEnum.Monday.destription);
System.out.println(TestWeekEnum.getDiscountType(3).destription);
// 枚舉是一種類型,用於定義變量,以限制變量的賦值;賦值時通過“枚舉名.值”取得枚舉中的值
TestWeekEnum testWeekEnum = TestWeekEnum.Sunday;
switch (testWeekEnum) {
case Monday:
System.out.println("week is Monday");
break;
case Tuesday:
System.out.println("week is Tuesday");
break;
case Thursday:
System.out.println("week is Thursday");
break;
case Wednesday:
System.out.println("week is Wednesday");
break;
case Friday:
System.out.println("week is Friday");
break;
case Saturday:
System.out.println("week is Saturday");
break;
case Sunday:
System.out.println("week is Sunday");
break;
default:
System.out.println("null");
break;
}
// 遍歷枚舉
System.out.println("遍歷TestWeekEnum枚舉中的值");
for (TestWeekEnum week : TestWeekEnum.values()){
System.out.println(week);
}
// 獲取枚舉的個數
System.out.println("TestWeekEnum枚舉中的值有" + TestWeekEnum.values().length + "個");
// 獲取枚舉的索引位置,默認從0開始
System.out.println(TestWeekEnum.Monday.ordinal());// 0
System.out.println(TestWeekEnum.Tuesday.ordinal());// 1
// 枚舉默認實現了java.lang.Comparable接口
System.out.println(TestWeekEnum.Monday.compareTo(TestWeekEnum.Sunday));// -1
}
}
enum 的語法結構儘管和 class 的語法不一樣,但是經過編譯器編譯之後產生的是一個class文件。該class文件經過反編譯可以看到實際上是生成了一個類,該類繼承了java.lang.Enum。實際上
enum 就是一個 class,只不過 java 編譯器幫我們做了語法的解析和編譯而已。