Map<String, String> map = new HashMap<String, String>();
map.put("A", "AAA");
map.put("B", "BBB");
map.put("C", "CCC");
map.put("D", "DDD");

// 第一种用for循环

for (Map.Entry<String, String> entry : map.entrySet()) {
System.out.println(entry.getKey() + "--->" + entry.getValue());
}

// 第二种用迭代

Set set = map.entrySet();
Iterator it = set.iterator();
while (it.hasNext()) {
Map.Entry<String, String> entry1 = (Map.Entry<String, String>) it.next();
System.out.println(entry1.getKey() + "==" + entry1.getValue());
}

Iterator it = map.keySet().iterator();
while (it.hasNext()) {
String key;
String value;
key = it.next().toString();
value = map.get(key);
System.out.println(key + "--" + value);
}

// 用entrySet()迭代

Iterator<Entry<String, String>> it = map.entrySet().iterator();
System.out.println(map.entrySet().size());
String key;
String value;
while (it.hasNext()) {
Map.Entry entry = it.next();
key = entry.getKey().toString();
value = entry.getValue().toString();
System.out.println(key + "====" + value);
}