当代码业务逻辑有多层 if else 时，不仅代码效率就会降低，而且也会影响代码美观，所以有没有方法可以解决这种多层 if 呢，答案肯定是有
1、使用享元模式+lamda
原代码：
if(key){
}else if(key1){
}
优化后：
public class StreamTest {
public static void main(String[] args) {
Product pro = new Product();
pro.setId(1);
Map<String,ProductService> map = new HashMap<>();
map.put("key", (param)->{param.setCreateDate(new Date());return param;});
map.put("key1", (param)->{param.setId(19);;return param;});
System.out.println(JSONObject.toJSONString(map.get("key1").excute(pro)));
}
public interface ProductService{
Product excute(Product pro);
}
}
原代码：
public class StreamTest {
public static void main(String[] args) {
Calendar cal = Calendar.getInstance();
cal.setTime(new Date());
int week = cal.get(Calendar.DAY_OF_WEEK) - 1;
String today = null;
switch(week){
case 0:
today = "周日";
break;
case 1 :
today = "周一";
break;
case 2 :
today = "周二";
break;
case 3 :
today = "周三";
break;
case 4 :
today = "周四";
break;
case 5 :
today = "周五";
break;
default:
today = "周六";
}
System.out.println(today);
}
}
使用享元模式后：
public class StreamTest {
public static void main(String[] args) {
Calendar cal = Calendar.getInstance();
cal.setTime(new Date());
int week = cal.get(Calendar.DAY_OF_WEEK) - 1;
String [] weekday = new String[]{"周日","周一","周二","周三",
"周四","周五","周六"};
String today = weekday [ week ];
System.out.println(today);
}
}
