CSci 2101 Data Structures: Lab 4

Problem 1: bank account

BankAccount class has two instance variables: the amount of money in the account and the PIN code. Unlike a real ATM code, which can only be 4 digits, the code in our example can be any integer. The class currently has the two instance variables (the amount and the code) and a constructor which initializes them. Note that the constructor takes two parameters, and so do two of the three methods that you have to write.

Your task is to write the three methods below according to the way they are described in comments and the testing code for each of these methods in the class TestBankAccount below.

public class BankAccount {
    private double amount; // the amount in the account
    private int code;       // the ATM code (can be any number)

    // Create a bank account with this amount and this code
    // Note that the method parameters theAmount and theCode
    // have different names than the instance variables amount
    // and code. Use this approach to avoid confusion between 
    // the instance variables and method parameters
    public BankAccount(double theAmount, int theCode) {
	amount = theAmount;
	code = theCode;
    }

    // ********************** deposit ********************************
    // a method deposit: 
    // takes two parameters (the additional amount and the code),
    // checks that the code is the same as the one stored in the 
    // instance variable 'code'. If they match, the method
    // adds the additional amount to the instance variable amount,
    // otherwise an error message is printed and the amount doesn't
    // change.
    



    // ********************** withdraw ********************************
    // a method withdraw: 
    // takes two parameters (the withdrawal amount and the code),
    // checks that the code is the same as the one stored in the 
    // instance variable 'code'. If they match, the method
    // checks if the amount is sufficient for the withdrawal.
    // If yes, the withdrawal amount is subtracted from the instance 
    // variable amount. Error messages should be printed if the code
    // is wrong or the amount is not sufficient

    


    // ****************** getBalance ************************* 
    // the method getBalance checks the PIN code and, if the code is correct,
    // returns the current account balance. If the code is incorrect,
    // the method prints an error message and returns 0 as the
    // balance. The state of the account doesn't change
   
}

public class TestBankAccount {
    public static void main(String [] args) {
	// create a bank account with the initial amount $352.33
	// and the code 123
	BankAccount myaccount = new BankAccount(352.33, 123); 
	// write your testing code here:


    }
}

Problem 2: jumping frogs

The class has three methods:

• printLocation prints the frog's coordinates (using System.out.println).
• jump which takes two integers: the first one is the increment for the coordinate x, the second is the increment for y. For instance, if fred is a variable of class Frog and its position is x = -3, y = -2, then calling fred.jump(5, -2) changes fred's position to x = 2, y = -4.
  If a frog lands in water, the method prints Splash!
• isInWater is a method that returns true if the frog is in water, and false if it's on the island.

This is the testing class for the class Frog. The two frogs make random jumps (with the parameters ranging between -5 and 5 for both x and y).

import java.util.*;

public class TestFrog {
    public static void main(String [] args) {
	Frog fred = new Frog();
	Frog frida = new Frog();

	// who will get in water first?

	// a random number generator
	Random r = new Random();
	
	// Each frog makes 10 random jumps 
	for(int i = 0; i < 10; ++i) {
	    System.out.println("Fred: ");
	    // fred's random jump. x and y increments are randomnly generated
	    // in the range from -5 to 5. 
	    // Why are there 11 possible values? 
	    fred.jump(r.nextInt(11) - 5, r.nextInt(11) - 5);
	    fred.printLocation();

	    // frida's random jump
	    System.out.println("Frida: ");
	    frida.jump(r.nextInt(11) - 5, r.nextInt(11) - 5);    
	    frida.printLocation();
	}
    }
}

• write the skeleton of the class Frog: set the instance variables, write the stubs for all three methods so that your program compiles and runs.
• write the code for the methods one by one, test them using the testing program.
• change the testing program so that it stops when the first frog reaches the water.