java 遍历Map的几种方法总结

/**
 * entrySet集合for-each循环（推荐使用）
 * 这种方式必须声明泛型类型:
 * a.bizData使用Map接收必须得声明泛型；b.for-each()里的Entry的泛型控制可有可无
 * Map的泛型控制通常使用<String,Object>
 */
Map<String, Object> bizData = dataBus.getBizData();
for (Entry<String, Object> entry : bizData.entrySet()) {
    System.out.println(entry.getKey() + "=" + entry.getValue());
}　

/**
 * entrySet集合迭代
 */
Iterator iterator = map.entrySet().iterator();
while (iterator.hasNext()) {
    Entry<String, Object> entry = iterator.next();
    System.out.println(entry.getKey() + "=" + entry.getValue()); 
}

/**
 * keySet集合迭代
 */
Iterator iterator = map.keySet().iterator();
while (iterator.hasNext()) {
  //获取键
  String key = iterator.next().toString();//或String key = (String)iterator.next();
  //根据键获取值
  Object value = map.get(key);
  System.out.println("键："+ key + "，值：" + value);
}

/**
 * keySet集合for-each循环
 */
for (String key:map.keySet()) {
  System.out.println(key + "=" + map.get(key));
}

//只遍历键
for (String key:map.keySet()) {
  System.out.println(key);
}

//只遍历值
for (Object val:map.values()) {
  System.out.println(val);
}