问什么小弟我的eclipse用不了枚举？同时小弟我想问什么情况下要用到枚举

package test1;import org.junit.Test;public class Demo_WeekDay{    @Test    public void test1()    {        print(Test5.WED);    }    public void print(Test5 g)    {        //String value1 = g.getValue() ;        String value1 = g.test_() ;        System.out.println(value1);    }    @Test    //遍历    public void sort()    {        Test5 g[] = Test5.values();        for(Test5 i : g)        {            System.out.println(i);        }    }    }    // 定义枚举enum Test5 {    SUN{        public String test_() {            return "星期日";        }    }    , MON{        public String test_() {            return "星期一";        }    }    , TUE{        public String test_() {            return "星期二";        }    }    , WED{        public String test_() {            return "星期三";        }    }    , THU{        public String test_() {            return "星期四";        }    }    , FRI{        public String test_() {            return "星期五";        }    }    , STA{        public String test_() {            return "星期六";        }            };    //private String value ;    /*private Test5(String value)    {        this.value = value ;    }*/    /*public String getValue()    {        return this.value ;    }*/   public abstract String test_();}