java:如何修复未经检查的转换警告

Question

我有以下代码:

private HashMap<Class<?>, HashMap<Entity, ? extends Component>> m_componentStores;

public <T extends Component> T getComponent(Entity e, Class<T> exampleClass)
{
    HashMap<Entity, ? extends Component> store = m_componentStores.get(exampleClass);

    T result = (T)store.get(e);

    if (result == null)
    {
        throw new IllegalArgumentException( "GET FAIL: "+e+" does not possess Component of class\nmissing: "+exampleClass );
    }

    return result;
}

当我编译时，它显示 T result = (T)store.get(e) 有一个未经检查的转换。

Type safety: Unchecked cast from capture#2-of ? extends Component to T

我缺少什么来防止出现此警告？

Answer 1

Class.cast 是您想要的。那么，您可能会考虑不使用反射。

改变行:

T result = (T)store.get(e);

到:

T result = exampleClass.cast(store.get(e));