# Java code refactoring example
## 例子1.(重構前) 依照考績決定動作

public static String Grade(String grade) {
		String result = "";
		switch (grade) {
			case "優":
				result = "出國去玩";
				break;
			case "甲":
				result = "買台電腦犒賞自己";
				break;
			case "乙":
				result = "去逛街放鬆心情";
				break;
			case "丙":
				result = "準備翻報紙找工作";
				break;
			default:
				result = "輸入錯誤，請重新輸入一次!";
		}
		return result;
	}

## 例子1(用多型取代)

abstract class Grade{
	abstract String getResult(String grade);
}

class Excellent extends Grade{
	String getResult(String grade) {
		return "出國去玩";
	}
}

class GradeA extends Grade{
	String getResult(String grade) {
		return "買台電腦犒賞自己";
	}
}

class GradeB extends Grade{
	String getResult(String grade) {
		return "去逛街放鬆心情";
	}
}

class GradeC extends Grade{
	String getResult(String grade) {
		return "準備翻報紙找工作";
	}
}

## 例子1(用hashmap取代條件句)

import java.io.IOException;
import java.util.HashMap;

public class Evaluate {

	public static void main(String[] args) {
		HashMap<String, String> m = buildMap();
		String grade = "優";
		try {
			System.out.println(m.get(grade));
		}
		catch(Exception e){
			System.out.println(e);
		}
		
	}
	public static HashMap<String, String> buildMap() {
		HashMap<String, String> map = new HashMap<String, String>();
		map.put("優", "出國去玩");
		map.put("甲", "買台電腦犒賞自己");
		map.put("乙", "去逛街放鬆心情");
		map.put("丙", "準備翻報紙找工作");
		return map;
	}
}

## 例子1(用enum搭配switch)

import java.io.IOException;

enum SomeCase{
		優{
			public String getResult() {
				return "出國去玩";
			}
		},
		甲{
			public String getResult() {
				return "買台電腦犒賞自己";
			}
		},
		乙{		
			public String getResult() {
				return "去逛街放鬆心情";
			}
		},
		丙{
			public String getResult() {
				return "準備翻報紙找工作";
			}
		};
		public abstract String getResult();	
}

public class Evaluate {
	public static void main(String[] args) {
		SomeCase ex = SomeCase.乙;
		switch (ex) {
		case 優:
		case 甲:
		case 乙:
		case 丙:
			System.out.println(ex.getResult());
			break;
		default:
			throw new IllegalArgumentException("輸入錯誤，請重新輸入一次!");
		}
	}
}

## 參考來源
* 書籍 : 最新 Java 8 程式語言(第四版) 作者： 施威銘研究室
範例頁數 : 5-20