1.遍歷map的最好方式 ，entryset.iterator()

使用泛型：

Map<Integer, Integer> map = new?HashMap<Integer, Integer>();

Iterator<Map.Entry<Integer, Integer>> entries = map.entrySet().iterator();

while?(entries.hasNext()) {

??Map.Entry<Integer, Integer> entry = entries.next();

??System.out.println("Key = "?+ entry.getKey() + ", Value = "?+ entry.getValue());

}

不使用泛型：

Map map = new?HashMap();

Iterator entries = map.entrySet().iterator();

while?(entries.hasNext()) {

??Map.Entry entry = (Map.Entry) entries.next();

??Integer key = (Integer)entry.getKey();

??Integer value = (Integer)entry.getValue();

??System.out.println("Key = "?+ key + ", Value = "?+ value);

}