D5 : com.google.common.collect.Multimap key可重複

com.google.common.collect.Multimap key可重複,可以處理相同key多值數據分析處理的工作，簡單實用。又稱超級map...

以下是代碼示例：

import java.util.Collection;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
import com.google.common.collect.ArrayListMultimap;
import com.google.common.collect.Multimap;

Map<String,String> cours = new HashMap<String,String>();
//加入測試數據
cours.put("易經", "伏羲氏");
cours.put("冰鑑", "左宗棠");
cours.put("道德經", "老子");
cours.put("思想家", "老子");
cours.put("哲學家", "老子");
cours.put("周易", "周文王");
//Multimap
Multimap<String,String> teachers = ArrayListMultimap.create();
//迭代器
Iterator<Map.Entry<String,String>> it = cours.entrySet().iterator();
while(it.hasNext()){
	Map.Entry<String,String> entry = it.next();
	String key = entry.getKey(); //課程
	String value = entry.getValue(); //教師	
	//教師 -->課程
	teachers.put(value, key);
}
//查看Multimap
Set<String> keyset = teachers.keySet();
for(String key:keyset){
Collection<String> col = teachers.get(key);
	System.out.print(key+":"+col+",");
}
//伏羲氏:[易經],左宗棠:[冰鑑],周文王:[周易],老子:[哲學家, 思想家, 道德經]