In Java, is it possible to assign a class or class object to a variable?
ThatClass obj= a; //a is any constant
Instead of ThatClass obj=new ThatClass(); //where the constructor is called and the integer (or any other value) in that constructor is then called/printed (see below).
ThatClass(){
final int constant=a;
System.out.println(constant);
}
I suspect not, but then again, Java continues to surprise me.
You obviously can assign class object to another class if the the class whose object you are assigning is a sub type. For example consider a class
class Bird
{
pulic Bird(String name)
{
System.out.println(name);
}
}
And now you create a sub class parrot like this
class Parrot extends Bird
{
public Parrot()
{
super("Parrot");
}
}
Now you create an object of Parrot.
Parrot p=new Parrot();
You can assign this to Bird
Bird b=p;
Even if you create a object of Bird like following
Bird b1=new Bird("A Bird");
You can assign this to another Bird variable like the following
Bird b2=b1;
If you want to access some fields of the class without creating objects of that class you have to decalre those fields as static.
class MyClass
{
final static int constant=a;
public static void show()
{
System.out.println(constant);
}
}
You can call the show() method like the following
MyClass.show();
Yes.
Class classType = String.class;
System.out.println(classType)
Should work.
No, There is no way you can do this.Basically, You are asking for boxing conversion and java only supports following boxing conversions.
From type boolean to type Boolean
From type byte to type Byte
From type short to type Short
From type char to type Character
From type int to type Integer
From type long to type Long
From type float to type Float
From type double to type Double
From the null type to the null type
*String is a special case.
Source: http://docs.oracle.com/javase/specs/jls/se7/html/jls-5.html#jls-5.1.7
