如何检查Java中收到的泛型方法？(How to check the generic my method received in Java?)

 我有一个set方法需要接受2种泛型： 
 
 
 
 Map<Long,Map<String,Object>>和 
 
 
 Map<Long,Map<String,String>> 
 
 
 但是我需要将其设置为Map<Long,Map<String,String>> 
 
 我知道String是一个Object，所以在参数中我可以使用Map<Long,Map<String,Object>> ，但是如果不需要，我不想进行转换。 使用instanceof似乎不起作用，给我一个错误： 
 
 
 
 无法对参数化类型Map<Long,Map<String,String>>执行instanceof检查。 请使用表单Map<?,?>因为在运行时将删除其他泛型类型信息 
 
 
 以下是我现在的现行代码。 
 
public void setRates(Map<Long,Map<String,Object>> inputRates){

    if(inputRates!=null){
        Map<Long,Map<String,String>> result = new HashMap<>();
        // if <Map<Long,Map<String,String>> do below :
        if(inputRates instanceof Map<Long,Map<String,String>>){
        //instanceof not working....   
            this.rates= inputRates;
        }else{
            // if really Map<Long,Map<String,Object>> do below - converting Object to String
            for (Map.Entry<Long, Map<String,Object>> entry1 : inputRates.entrySet()) {
                Map<String,String> resultMap = new HashMap<>(); 

                Long key = entry1.getKey();
                Map<String,Object> inputMap = entry1.getValue();
                for(Map.Entry<String,Object> entry2 : inputMap.entrySet()) { 
                    String key2 = entry2.getKey();
                    Object value2 = entry2.getValue();
                    if(value2!=null){
                        resultMap.put(key2, value2.toString());  
                    }else{
                        resultMap.put(key2, null);  
                    }
                }
                result.put(key, resultMap);
            }
            this.rates = result;
        } 
    }
}
 
 关于我如何实现这个的任何想法？ 

I have a set method that need to accept 2 kind of generics : 
 
 
 
Map<Long,Map<String,Object>>, and 
 
 
Map<Long,Map<String,String>>
 
 
However I need to set it as Map<Long,Map<String,String>> 
 
I know that String is an Object, so in the parameter I can use Map<Long,Map<String,Object>>, however I don't want to undergo a conversion if there no need to. Using instanceof seems not working, throwing me with error:
 
 
 
Cannot perform instanceof check against parameterized type Map<Long,Map<String,String>>. Use the form Map<?,?> instead since further generic type information will be erased at runtime
 
 
Below is current codes I have now. 
 
public void setRates(Map<Long,Map<String,Object>> inputRates){

    if(inputRates!=null){
        Map<Long,Map<String,String>> result = new HashMap<>();
        // if <Map<Long,Map<String,String>> do below :
        if(inputRates instanceof Map<Long,Map<String,String>>){
        //instanceof not working....   
            this.rates= inputRates;
        }else{
            // if really Map<Long,Map<String,Object>> do below - converting Object to String
            for (Map.Entry<Long, Map<String,Object>> entry1 : inputRates.entrySet()) {
                Map<String,String> resultMap = new HashMap<>(); 

                Long key = entry1.getKey();
                Map<String,Object> inputMap = entry1.getValue();
                for(Map.Entry<String,Object> entry2 : inputMap.entrySet()) { 
                    String key2 = entry2.getKey();
                    Object value2 = entry2.getValue();
                    if(value2!=null){
                        resultMap.put(key2, value2.toString());  
                    }else{
                        resultMap.put(key2, null);  
                    }
                }
                result.put(key, resultMap);
            }
            this.rates = result;
        } 
    }
}
 
Any idea on how I implement this?

原文：https://stackoverflow.com/questions/49535198