泛型方法实现 传入类型和返回类型一致(当参数是HashMap时返回HashMap,TreeMap时返回TreeMap)

实现:

根据需要实现返回类型是HashMap<String,Object> 或者TreeMap<String,Object>

// 方法 当传入是HashMap<String,Object>时,返回HashMap<String,Object>;当传入是TreeMap<String,Object>时,返回TreeMap<String,Object>
public static  <T extends Map<String,Object>> T 
　　createSignMap(T params,String token,String orderNo){
       params.put("token", token);
       params.put("orderNo", orderNo);
       return params;
}

// 调用:返回HashMap<String,Object>
HashMap<String,Object> transMap = new HashMap<String,Object>();
transMap = createSignMap(transMap,token,orderNo,);               

上面版本提示:Variable is already assigned to this value [变量已分配给该值]

警告敏感:

// 方法 当传入是HashMap<String,Object>时,返回HashMap<String,Object>;当传入是TreeMap<String,Object>时,返回TreeMap<String,Object>
public static  <T extends Map<String,Object>> T 
　　createSignMap(T params,String token,String orderNo){
       params.put("token", token);
       params.put("orderNo", orderNo);
       return params;
}
// 调用:返回HashMap<String,Object>
HashMap<String,Object> transMap = new HashMap<String,Object>();
createSignMap(transMap,token,orderNo,);