To answer this question, let's go through each line of the code:
In the Mixer
class, there are two constructors:
Mixer()
- This is a default constructor that does not take any arguments.
Mixer(Mixer m)
- This constructor takes a Mixer
object as an argument and assigns it to the instance variable ml
.
Inside the main
method:
Mixer m2 = new Mixer();
- This creates a new Mixer
object called m2
using the default constructor.
Mixer m3 = new Mixer(m2);
- This creates a new Mixer
object called m3
using the constructor that takes a Mixer
object as an argument. The argument m2
is passed to this constructor.
m3.go();
- This calls the go()
method on m3
, which prints "hi ".
Mixer m4 = m3.m1;
- This assigns the value of m3.m1
(which is null
because it has not been initialized) to m4
.
m4.go();
- This calls the go()
method on m4
, which also prints "hi ".
Mixer m5 = m2.m1;
- This assigns the value of m2.m1
(which is null
because it has not been initialized) to m5
.
m5.go();
- This calls the go()
method on m5
, which also prints "hi ".
The output of the code will be: "hi hi ".
Therefore, the correct answer is F) "hi hi, followed by an exception".