// Exercise 3.6 Solution

// Small.java

// Program finds the smallest of several letters

import java.io.*;

public class Small {

public static void main( String args[] ) throws IOException

{

int smallest = 'Z', temp, number;

System.out.println( "Enter a digit followed by characters" );

// subtract unicode value of 48 (the value of

// character '0') to get the actual numeric value

number = System.in.read() - 48;

smallest = System.in.read();

for ( int x = 2; x <= number; x++ ) {

temp = System.in.read();

if ( temp < smallest )

smallest = temp;

}

char smallest2 = ( char ) smallest;

System.out.println( "Smallest letter is " + smallest2 );

}

}

// Exercise 3.8 Solution

// Factorial.java

// Program calculates factorials

import java.applet.Applet;

import java.awt.*;

public class Factorial extends Applet {

public void paint( Graphics g )

{

int fact, y = 20;

g.drawString( "X", 5, 10 );

g.drawString( "X!", 70, 10 );

for ( int z = 1; z <= 5; z++ ) {

fact = 1;

for ( int w = 1; w <= z; w++ )

fact *= w;

g.drawString( String.valueOf( z ), 5, y );

g.drawString( String.valueOf( fact ), 70, y );

y += 10;

}

}

}

// Exercise 3.9 Solution

// Interest.java

// Calculating compound interest

// NOTE: the Math.floor method is used to round

// a number to a specific decimal place. It is

// used here to round the number to the hundredths.

import java.applet.Applet;

import java.awt.*;

public class Interest extends Applet {

public void paint( Graphics g )

{

double amount, principal = 1000.00, rate;

int yPos = 40, xPos = 60;

g.drawString( "Year", 25, 25 );

for ( rate = 0.05; rate <= 0.10; rate += .01 ) {

rate = Math.floor( rate * 100 + 0.5 ) / 100;

g.drawString( String.valueOf( rate ), xPos, 25 );

for ( int year = 1; year <= 10; year++ ) {

amount = principal * Math.pow( 1.0 + rate, year );

amount = Math.floor( amount * 100 + 0.5 ) / 100;

g.drawString( Integer.toString( year ), 25, yPos );

g.drawString( Double.toString( amount ), xPos, yPos );

yPos += 15;

}

yPos = 40;

xPos += 60;

}

}

}

// Exercise 3.10 Solution

// Triangles.java

// Program prints triangles

public class Triangles {

public static void main( String args[] )

{

int row, column, space;

// part a

for ( row = 1; row <= 10; row++ ) {

for ( column = 1; column <= row; column++ )

System.out.print( '*' );

System.out.println();

}

System.out.println();

// part b

for ( row = 10; row >= 1; row-- ) {

for ( column = 1; column <= row; column++ )

System.out.print( '*' );

System.out.println();

}

System.out.println();

// part c

for ( row = 10; row >= 1; row-- ) {

for ( space = 10; space > row; space-- )

System.out.print( ' ' );

for ( column = 1; column <= row; column++ )

System.out.print( '*' );

System.out.println();

}

System.out.println();

// part d

for ( row = 10; row >= 1; row-- ) {

for ( space = 1; space < row; space++ )

System.out.print( ' ' );

for ( column = 10; column >= row; column-- )

System.out.print( '*' );

System.out.println();

}

}

}

// Exercise 3.11 Solution

// Graphs.java

// Program prints histograms

import java.applet.Applet;

import java.awt.*;

import java.awt.event.*;

public class Graphs extends Applet implements ActionListener {

TextField input;

Label inputLabel;

boolean enablePaint;

int count, num1, num2, num3;

int num4, num5, temp;

public void init()

{

input = new TextField( 4 );

input.addActionListener( this );

inputLabel = new Label( "Enter number:" );

add( inputLabel );

add( input );

}

public void actionPerformed( ActionEvent e )

{

enablePaint = false;

temp = Integer.parseInt( input.getText() );

if ( temp >= 1 && temp <= 30 ) {

++count;

showStatus( "Entry number " + count );

switch ( count ) {

case 1:

num1 = temp;

break;

case 2:

num2 = temp;

break;

case 3:

num3 = temp;

break;

case 4:

num4 = temp;

break;

case 5:

num5 = temp;

break;

}

if ( count == 5 )

enablePaint = true;

}

else

showStatus( "Number must be between 1 and 30!" );

repaint();

}

public void paint( Graphics g )

{

if ( enablePaint == true ) {

int z, x, y = 0, value = 0;

for ( ; count > 0; count-- ) {

x = 5;

switch ( count ) {

case 1:

y = 50;

value = num1;

break;

case 2:

y = 60;

value = num2;

break;

case 3:

y = 70;

value = num3;

break;

case 4:

y = 80;

value = num4;

break;

case 5:

y = 90;

value = num5;

break;

}

for ( z = 1; z <= value; z++ )

g.drawString( "*", x += 5, y );

}

}

}

}

// Exercise 3.12 Solution

// Sales.java

// Program calculates sales

import java.applet.Applet;

import java.awt.*;

import java.awt.event.*;

public class Sales extends Applet implements ActionListener {

TextField input, input2;

Label inputLabel, inputLabel2;

float product1, product2, product3;

float product4, product5;

public void init()

{

input = new TextField( 4 );

input2 = new TextField( 4 );

input2.addActionListener( this );

inputLabel = new Label( "Enter product number (1-5):" );

inputLabel2 = new Label( "Enter quantity sold: " );

add( inputLabel );

add( input );

add( inputLabel2 );

add( input2 );

}

public void actionPerformed( ActionEvent e )

{

showStatus( "" );

if ( e.getSource() == input2 ) {

int productId = Integer.parseInt( input.getText() );

int temp = Integer.parseInt( input2.getText() );

if ( productId >= 1 && productId <= 5 ) {

switch ( productId ) {

case 1:

product1 += temp * 2.98;

break;

case 2:

product2 += temp * 4.50;

break;

case 3:

product3 += temp * 9.98;

break;

case 4:

product4 += temp * 4.49;

break;

case 5:

product5 += temp * 6.87;

break;

}

}

else

showStatus( "Product number must be between 1 and 5!" );

}

repaint();

}

public void paint( Graphics g )

{

g.drawString( "Totals", 5, 80 );

g.drawString( "Product 1: ", 5, 90 );

g.drawString( "$ " + product1, 100, 90 );

g.drawString( "Product 2: ", 5, 100 );

g.drawString( "$ " + product2, 100, 100 );

g.drawString( "Product 3: ", 5, 110 );

g.drawString( "$ " + product3, 100, 110 );

g.drawString( "Product 4: ", 5, 120 );

g.drawString( "$ " + product4, 100, 120 );

g.drawString( "Product 5: ", 5, 130 );

g.drawString( "$ " + product5, 100, 130 );

}

}

// Exercise 3.19 Solution

// Triangles.java

// Program prints triangles

public class Triangles {

public static void main( String args[] )

{

int row, column, space;

for ( row = 1; row <= 10; row++ ) {

// part a

for ( column = 1; column <= row; column++ )

System.out.print( '*' );

for ( space = 1; space <= 10 - row; space++ )

System.out.print( ' ' );

System.out.print( "\t" );

// part b

for ( column = 10; column >= row; column-- )

System.out.print( '*' );

for ( space = 1; space < row; space++ )

System.out.print( ' ' );

System.out.print( "\t" );

// part c

for ( space = 10; space > row; space-- )

System.out.print( ' ' );

for ( column = 1; column <= row; column++ )

System.out.print( '*' );

System.out.print( "\t" );

// part d

for ( space = 1; space < row; space++ )

System.out.print( ' ' );

for ( column = 10; column >= row; column-- )

System.out.print( '*' );

System.out.println();

}

}

}