Question

JAVA

In this lab, you will implement a vending machinethat holds cans of soda. To buy a can of soda, the customer needs to insert a token into the machine. When the token is inserted, a can drops from the can reservoir into the product delivery slot. The vending machine can be filled with more cans. The goal is to determine how many cans and tokens are in the machine at any given time.

Instances of a class with no constructor are always constructed with all instance variables set to zero (or nullif they are object references). It is always a good idea to provide an explicit constructor.

Provide two constructors for the VendingMachineclass:

a) A constructor with no arguments that initializes the vending machine with 10 soda cans

b) A constructor, VendingMachine(int cans), that initializes the vending machine with the given number of cans

Both constructors should initialize the token count to 0.

Answer 1

VendingMachine.java

public class VendingMachine {
private int cans, tokens;
  
// default constructor
public VendingMachine()
{
this.cans = 10;
this.tokens = 0;
}

// explicit constructor
public VendingMachine(int cans)
{
this.cans = cans;
this.tokens = 0;
}
  
private void refill()
{
this.cans = 10;
System.out.println("The Vending Machine is refilled with 10 cans.");
}
  
public void buyCan()
{
this.tokens++;
this.cans--;
if(this.cans == 0)
refill();
}

public int getCans() {
return cans;
}

public int getTokens() {
return tokens;
}
  
@Override
public String toString()
{
return("Number of tokens: " + this.tokens + ", Number of cans: " + this.cans);
}
}

VendingMachineTest.java (Driver class)

public class VendingMachineTest {
  
public static void main(String[] args)
{
VendingMachine machine = new VendingMachine(20);
  
System.out.println("INITIAL STATE:\n" + machine.toString());
  
// initiate to buy 15 cans
System.out.println("\nAttempting to buy 15 cans...");
for(int i = 0; i < 15; i++)
{
machine.buyCan();
}
// display the number of cans and tokens inside the machine
System.out.println("\nAFTER BUYING 15 CANS:\n" + machine.toString());
  
// again buy 10 cans
System.out.println("\nAttempting to buy 10 cans...");
for(int i = 0; i < 10; i++)
{
machine.buyCan();
}
// display the number of cans and tokens inside the machine
System.out.println("\nAFTER BUYING 10 CANS:\n" + machine.toString());
}
}

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