Object reference not set to an instance of an object

Question

---------------------------A1.cs------------------------------

public class A1
{
public B1 AA { get; set; }
}

public class B1
{
public C1 BB { get; set; }
}

public class C1
{
public D1 CC { get; set; }
}

public class D1
{
public E1 DD { get; set; }
}

public class E1
{
public string EE { get; set; }
}

--------------------Default.aspx.cs------------------

protected void Page_Load(object sender, EventArgs e)
{
try
{
A1 ObjA = new A1();
ObjA.AA.BB.CC.DD.EE = "";
}
catch (Exception ex)
{
}
}

As Above i have show the code when is try to access ObjA.AA.BB.CC.DD.EE = ""; this line showing error Object reference not set to an instance of an object

Tapan Patel · Answer

For any of the methods to be accessed you need to have an object created.

Salman · Answer

Hi. You created the object of A1 class and you can do objA.AA=. But you can not do objA.BB= because BB belongs to a different class B1. For that you need to do B1 objB=new B1(); and objB.BB=; for all other class also you need to do the same. that's the reason why it showing object reference not set to an instance of an object. Thanks.