我有以下代码:使用Java泛型错误
String test = "[{\"color\":\"red\"}]";
Class<? extends Base> baseObject = Base.class;
Collection<? extends Base> elements = new ArrayList<Base>();
if (test.startsWith("[")) {
elements.addAll(new ObjectMapper().readValue(test, Collection.class));
} else {
elements.add(new ObjectMapper().readValue(test, baseObject));
}
但是我对
elements.addAll(new ObjectMapper().readValue(test, Collection.class));
得到一个编译警告:
The expression of type Collection needs unchecked conversion to conform to Collection<? extends capture#1-of ? extends Base>
和elements.add(new ObjectMapper().readValue(test, baseObject));
编译错误:
The method add(capture#2-of ? extends Base) in the type Collection<capture#2-of ? extends Base> is not applicable for the arguments (capture#3-of ? extends Base)
出什么问题了?
*什么*错误? –
为什么不简单'收集 元素=新的ArrayList ();'? –
assylias
'String test =“[{”color“:”red}]“;'< - 我认为你忘了逃脱引号 –