You will hand in this exercise. Download and complete the starter file here: Combination.java.

Implement a class, called Combination, to store three integer values $($ints$).$

declare the necessary instance variables to store the three integer values;

create a constructor, public Combination$($int first, int second, int third$),$ to initialize the values of this object.

implement the instance method public boolean equals$($Combination other$),$ such that equals returns true if other contains the same values, in the same order, as this Combination; the order is defined by the order of the parameters of the constructor, given the following:

Combination c$1,$ c$2,$ c$3$;

c$1=$ new Combination$(1,2,3)$;

c$2=$ new Combination$(1,2,3)$;

c$3=$ new Combination$(3,2,1)$;

then c$1.$equals$($c$2)$ is true but c$1.$equals$($c$3)$ is false;

finally, implement the method public String toString$(),$ to return a String representation of this object, where the first, second and third values are concatenated and separated by $$:$$ symbols. E$.$g$.$

Combination c$1$;

c$1=$ new Combination$(1,2,3)$;

System.out.println$($c$1)$;

displays $1$:$2$:$3.$

The interface of the class Combination consists therefore of its constructor, the method equals and the method toString.

Ideally, the input data should be validated. In particular, all the values should be in the range $1$ to $5.$ However, since we do not yet have the tools to handle exceptional situations, we will assume $($for now$)$ that all the input data are valid!

Note: Simpler code is better and it is worthwhile spending time cleaning up code even if it was already working.

Hint: my implementation is approximately $20$ lines long, not counting blank lines. This is not a contest to write the shortest class declaration. I am providing this information so that you can evaluate the relative complexity of the tasks.

$4.$ DoorLock

You will hand in this exercise. Download and complete the starter file here: DoorLock.java.

Create an implementation for the class DoorLock described below.

declare an integer constant, called MAX$\_$NUMBER$\_$OF$\_$ATTEMPTS, that you will initialize to the value $3$;

instance variables. The class DoorLock must have the necessary instance variables to

store an object of the class Combination

to represent the property of being opened or closed

to represent its activation state $($the door lock is activated or deactivated$),$ and

to count the number of unsuccessful attempts at opening the door;

the class has a single constructor, DoorLock$($ Combination combination $),$ which initializes this instance with a combination. When a door lock is first created, the door lock is closed. Also, when the object is first created, it is activated and the number of failed attempts at opening it should be zero;

implement the instance method public boolean isOpen$()$ that returns true if this door lock is currently opened and false otherwise;

implement the instance method public boolean isActivated$()$ that returns true if this door lock is currently activated and false otherwise;

implement the instance method public void activate$($Combination c$)$ that sets the instance variable $$activated$$ to true if the parameter c $$equals$$ to the combination of this object;

finally, implement the instance method public boolean open$($ Combination combination $)$ such that

an attempt is made at opening this door lock only if this door lock is activated

if the parameter combination $$equals$$ to the combination of this door lock, set the state of the door to be open, and the number of failed attempts should be reset to zero

otherwise, i$.$e$.$ if the wrong Combination was supplied, the number of failed attempts should be incremented by one,

if the number of failed attempts reaches MAX$\_$NUMBER$\_$OF$\_$ATTEMPTS, this door lock should be deactivated.

Hint: my implementation is approximately $40$ lines long, not counting the blank lines.

$5.$ SecurityAgent $($if there is time$)$

Implement the class SecurityAgent described below.

instance variables. A security agent is responsible for a particular door lock. Declare the necessary instance variables such that a SecurityAgent

remembers $($stores$)$ a Combination and

has access to this particular DoorLock, i$.$e$.$ maintains a reference to a DoorLock object;

implement a constructor with no parameter such that when a new SecurityAgent is created

it creates a new Combination and stores it$,$

it creates a new DoorLock with this saved Combination. For the sake of simplicity, you may decide to always use the same combination:

Combination secret;

secret $=$ new Combination$(1,2,3)$;

if secret is the name of the instance variable that is used to remember the Combination. Or$,$ you can let your SecurityAgents use their imagination, so that each SecurityAgent has a new Combination that it only knows.

int first, second, third;

first $=($int$)($Math$.$random$()*5)+1$;

second $=($int$)($Math$.$random$()*5)+1$;

third $=($int$)($Math$.$random$()*5)+1$;

secret $=$ new Combination$($first$,$ second, third$)$;

Alternative w