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public class test<T> {
private final Map<Class<?>, Class<?>> map1 = new HashMap();
private final Map<?, ?> map2 = new HashMap();
public void put(Class<T> clazz, T t){
map1.put(clazz, clazz);//可以编译成功
map2.put(t, t); //编译失败
}
}
private final Map<String, String> map1 = new HashMap();
private final Map<String, String> map2 = new HashMap<String,String>();
private final Map map3 = new HashMap();
private final Map<Object, Object> map4 = new HashMap();
map1和map2 有什么区别? map3和map4有什么区别?