override - Why are contravariant parameter types in Java not allowed for overriding? -


when overriding method of superclass, java allows return type covariant.

why contravariant parameter types in contrast not allowed when overriding methods?

because that's called overloading.

in particular, return type type can covariant because not considered when overloading, , therefore still matches superclass or interface's implementation. parameters considered when overloading. might have optimization number dosomethingwithnumber(integer value) compared number dosomethingwithnumber(number value).


Comments

Post a Comment

Popular posts from this blog

android - Pass an Serializable object in AIDL -

i have defined aidl file interface imyfeature { void dotask(class clazz); } but need pass class object process. possible in android? if so, how? i tried: interface imyfeature { serializable class; void dotask(class clazz); } but doesn’t work. aidl in android supports custom class implement parcelable interface. in case want send class object not possible. can send class canonical name , retrieve in service. for example have aidl file interface imyfeature { void dotask(string classname); } then call : binder.dotask(myclass.class.getcanonicalname()); and in service binder stub implementation : private final imyfeature mbinder = new imyfeature.stub() { public void dotask(string classname) { try { class<?> clazz = class.forname(classname); constructor<?> ctor = clazz.getconstructor((class[]) null); object object = ctor.newinstance(); ...
Read more

How to provide Authorization & Authentication using Asp.net, C#? -

Image
i have asp.net application in c#. i have provide page authorization specific user/usergroup. i have created 2 tables in database: 1) pagename 2)permissions[insert, update, view, delete] but i'm unable match tables , permissions assigning... can 1 please me, how created tables in database , how coding. please me. you can below explanation. configure access specific file , folder, set forms-based authentication. request page in application redirected logon.aspx automatically. in web.config file, type or paste following code. this code grants users access default1.aspx page , subdir1 folder . <configuration> <system.web> <authentication mode="forms" > <forms loginurl="login.aspx" name=".aspnetauth" protection="none" path="/" timeout="20" > </forms> </authentication> <!-- section denies access files in...
Read more

How to use Authorization & Authentication in Asp.net, C#? -

i using roll management , trying give page , folder access according user or user group, using server created ad group user authentication. i have default1.aspx page default , subdir1 folder give different access separate user group i using below logic in web.config. <location path="subdir1"> <system.web> <authorization> <allow users ="?" /> </authorization> </system.web> </location> i facing problem provide same access 2 or more directory same user should have provide allow user code twice both folder? i can use logic repeating value folder want access providing in 1 logic. i have got answer configure folder/page access, have make different access shown below.. configure access specific file , folder, set forms-based authentication. request page in application redirected logon.aspx automatically. in web.config file, done following code. this code grants user...
Read more