Soution Q1:

-----------

import javax.swing.*;

import java.awt.*;

public class RollDie {

public static void main( String args[] )

{

final int MAX = 100;

int side, frequency[] = new int[7];

String output = "Side\tFrequency\tHistogram", info = "";

for (int roll=0; roll<MAX; roll++)

{

side = (int) (1 + Math.random() * 6);

++frequency[side];

}

for (side=1; side<frequency.length; side++)

{

info += side + "\t" + frequency[side] +"\t";

for (int star = 1; star <= frequency[side]; star++)

info += "*";

if(side != (frequency.length - 1))

info +=" \n";

else

info +=" ";//optionel

}

JTextArea outputArea[] = {new JTextArea(output), new JTextArea(info)};

outputArea[0].setFont(new Font("Courier", Font.BOLD, 12));

JOptionPane.showMessageDialog(null, outputArea,

"Rolling a Die 100 Times", JOptionPane.INFORMATION_MESSAGE);

}

}

Solution Q2:

import java.awt.*;

import java.awt.event.*;

import javax.swing.*;

public class BorderLayoutDemo extends JFrame implements ActionListener {

private JButton b[];

private String names[] = { "Hide North", "Hide South", "Hide East",

"Hide West", "Hide Center" };

private BorderLayout layout;

public BorderLayoutDemo()

{

super("BorderLayout Demo");

layout = new BorderLayout();

Container c = getContentPane();

c.setLayout(layout);

// instantiate button objects

b = new JButton[names.length];

for (int i = 0; i < names.length; i++)

{

b[i] = new JButton(names[i]);

b[i].addActionListener(this);

}

// order not important

c.add(b[0], BorderLayout.NORTH); // North position

c.add(b[1], BorderLayout.SOUTH); // South position

c.add(b[2], BorderLayout.EAST); // East position

c.add(b[3], BorderLayout.WEST); // West position

c.add(b[4], BorderLayout.CENTER); // Center position

setSize(300,200);

show();

}

public void actionPerformed(ActionEvent e)

{

for (int i = 0; i < b.length; i++)

{

if (e.getSource() == b[i])

b[i].setVisible(false);

else

b[i].setVisible(true);

}

// re-layout the content pane

layout.layoutContainer(getContentPane());

}

public static void main(String args[])

{

BorderLayoutDemo app = new BorderLayoutDemo();

}

}

Solution Q3:

class Account

{

//private NumberFormat fmt = NumberFormat.getCurrencyInstance();

// Balance accessible by Account, and subclasses of Account

protected double balance;

// Constructor to initialise balance

public Account(double amount)

{

balance = amount;

}

// Overloaded constructor for empty balance

public Account()

{

balance = 0.0;

}

public void deposit(double amount)

{

balance += amount;

}

public double withdraw(double amount)

{

// See if amount can be withdrawn

if (balance >= amount)

{

balance -= amount;

return amount;

}

else

// Withdrawal not allowed

{

System.out.println("Insufficient fund: Withdrawal denied!");

return 0.0;

}

}

public double getbalance()

{

return balance;

}

}

class InterestBearingAccount extends Account

{

// Default interest rate of 2.5 percent (const)

private static double default_interest = 2.5;

// Current interest rate

private double interest_rate;

// Overloaded constructor accepting balance and an interest rate

public InterestBearingAccount(double amount, double interest)

{

balance = amount;

interest_rate = interest;

}

// Overloaded constructor accepting balance with a default interest rate

public InterestBearingAccount(double amount)

{

balance = amount;

interest_rate = default_interest;

}

// Overloaded constructor with empty balance and a default interest rate

public InterestBearingAccount()

{

balance = 0.0;

interest_rate = default_interest;

}

void add_monthly_interest()

{

// Add interest to our account

balance = balance +

(balance * interest_rate / 100) / 12;

}

}

import java.text.DecimalFormat;

class AccountDemo

{

public static void main(String args[])

{

DecimalFormat precision = new DecimalFormat( "0.00" );

// Create accounts:

InterestBearingAccount my_account1 = new InterestBearingAccount();

InterestBearingAccount my_account2 = new InterestBearingAccount(250);

InterestBearingAccount my_account3 = new InterestBearingAccount(300, 8.5);

// Deposit money in first account:

my_account1.deposit(150.00);

// Print current balance of first account:

System.out.println ("Current balance in account1 $" +

precision.format(my_account1.getbalance()));

// Withdraw money

my_account2.withdraw(275.0);

my_account3.withdraw(15.0);

// Allow a month to pass

my_account1.add_monthly_interest();

my_account2.add_monthly_interest();

my_account3.add_monthly_interest();

// Print new balances

System.out.println ("New balance in account1 $" +

precision.format(my_account1.getbalance()));

System.out.println ("New balance in account2 $" +

precision.format(my_account2.getbalance()));

System.out.println ("New balance in account2 $" +

precision.format(my_account3.getbalance()));

}

}