Slide Show Applet

/* Java applet to display sildeshow to images from a given folder in thumbnail form, images can be selected one by one and can be enable/disable slideshow of images. The thumbnail images are placed in slides folder, the download button(rectangle) downloads the images from the web server, hence a webserver is required eg : any webserver even tomcat webserver with download folder with images*/

/* Requirements
1. Name of java file : Sildeshow.java
2. Name of images folder : slides
3. Names of images 1.jpg, 2.jpg and so on upto 8.jpg.
3. Name of download folder in webserver : download
4. Download images given below and paste them in slides folder :
1.jpg │2.jpg │3.jpg │4.jpg │5.jpg │6.jpg │7.jpg │8.jpg
5. Download images given below and paste them in download folder in webserver :
1.jpg │ 2.jpg │ 3.jpg │4.jpg │5.jpg │6.jpg │7.jpg │8.jpg

Java Code for Sildeshow

import java.applet.*;
import java.awt.*;
import java.awt.event.*;
import java.net.*;
public class Slideshow extends Applet implements Runnable
{
// Variable Declaration
Thread runner;
boolean left,right,click,auto;
boolean but0,but1;
boolean b0,b1;
boolean waitMessage = true;
String str_desc[] = { // Display Messages
" This is an Abstract piece.Painted on:20/11/86.",
" This picture is an Abstract work.Painted on:10/1/89.",
" This picture is a Canvas oil painting (15/8/92).",
" This is a Pastel painting (2/10/99).",
" This picture is an Abstract piece.Painted on:6/5/03.",
" This is a Brush painting (2/6/05).",
" This a painted collage (30/1/83).",
" This is my Graphical art piece.Painted on:20/12/08."};
int number=1;
static final int MAX=8;
Image Picture[]=new Image[MAX]; // Image variable
Image Buffer;
Graphics gBuffer; // Graphics Variable
Font a = new Font("Helvetica", Font.PLAIN,12);
Font b = new Font("Dialog", Font.PLAIN,10);
Font c = new Font("Helvetica", Font.BOLD,13);
Rectangle r0=new Rectangle(400,70,50,20); // ON / OFF
Rectangle r1=new Rectangle(400,195,120,20); // Click Here
void loadGraphics()
{ //
Track the status of a number of media objects
MediaTracker t=new MediaTracker(this);
for(int i=0;i< MAX;i++)
{
// Load an image in an applet
Picture[i]=getImage(getCodeBase(),"slides/"+(i+1)+".jpg");
t.addImage(Picture[i],0);
try{
t.waitForAll(0);
}
catch(InterruptedException e)
{
}
waitMessage=false;
}
}

public void init()
{
// Creates an image
Buffer=createImage(size().width,size().height);
gBuffer=Buffer.getGraphics();
// Creates a graphics context for this component
}
public void start()
{
if (runner == null)
{
runner = new Thread (this);
runner.start();
}
}
public void stop()
{
if (runner != null)
{
runner.stop();
runner = null;
}
}
public void run()
{
while(true)
{
try
{
runner.sleep(2500);
}
catch (Exception e)
{ }
if(auto)
{
if(number< MAX)
number++;
else
number=1;
}
repaint();
}
}
public void update(Graphics g)
{ paint(g); }
public void drawArrow(int w,int h,int x,int y,boolean left,boolean over,boolean click)
{
if(click&&over) // set color to yellow on click or mouse over
gBuffer.setColor(Color.yellow);
else
if(over) // set color to orange on mouse over
gBuffer.setColor(Color.orange);
else
// set color to red on click
gBuffer.setColor(Color.red);
if(left)
{
int al[] = {x,x+w,x+w};
int bl[] = {y+h/2,y,y+h};
gBuffer.fillPolygon(al, bl, 3);
}
else {
int ar[] = {x,x,x+w};
int br[] = {y,y+h,y+h/2};
gBuffer.fillPolygon(ar, br, 3);
}
}
public void drawPanel()
{
gBuffer.setColor(Color.white);
gBuffer.fillRect(0,0,size().width,size().height);
// Display Text
drawArrow(40,40,330+70,120,true,left,click);
// Display Left Arrow
drawArrow(40,40,380+70,120,false,right,click);
// Display Right Arrow
gBuffer.setColor(Color.lightGray);
gBuffer.setFont(b);
gBuffer.setColor(auto?Color.orange:Color.lightGray);
gBuffer.fill3DRect(400,70,50,20,!but0);
// Rectangle for ON rectangle
gBuffer.setColor(b0?Color.red:Color.black);
// Color For ON rectangle
String s=auto?"OFF":"ON";
gBuffer.drawString(s,410,85);
gBuffer.setColor(Color.lightGray);
// Download
s="Click Here";
gBuffer.fill3DRect(400,190,120,20,!but1);
gBuffer.setFont(a);
gBuffer.setColor(b1?Color.red:Color.black);
gBuffer.drawString(s,430,205);
// Display Image
gBuffer.drawImage(Picture[number-1],20,20,this);
gBuffer.setColor(Color.black);
gBuffer.setFont(c);
gBuffer.drawString("Slideshow:",300,80);
gBuffer.drawString("Scroll:",300,140);
gBuffer.drawString("Download it!",300,200);
gBuffer.drawString("Description:",300,35);
gBuffer.setFont(a);
gBuffer.drawString(str_desc[number-1],300,50);
}
public boolean mouseDown(Event evt,int x,int y)
{
if(r0.inside(x,y))
{
but0=true; auto^=true;
}
if(r1.inside(x,y))
{
but1=true;
auto=false;
}
if(but1)
{
String link ="http://localhost:8080/download/"+number+".jpg";
try {
// corresponds to an applet's environment
AppletContext a = getAppletContext();
URL url = new URL(link);
// url of the image to be downloaded
a.showDocument(url,"_blank");
}
catch (MalformedURLException e){
System.out.println(e.getMessage());
}
}
if(left)
{
auto=false;
if(number>1)
number--;
else number=8;
}
if(right)
{
auto=false;

if(number< MAX)
number++;
else
number=1;
}
click=true;
repaint();
return true;
}
public boolean mouseUp(Event evt,int x,int y)
{
but0=but1=click=false;
repaint();
return true;
}
public boolean mouseMove(Event evt,int x,int y)
{
Rectangle rl=new Rectangle(330+70,120,40,40);
Rectangle rr=new Rectangle(380+70,120,40,40);
if(rl.inside(x,y))
left=true;
else
left=false;
if(rr.inside(x,y))
right=true;
else
right=false;
if(r0.inside(x,y))
b0=true;
else
b0=false;
if(r1.inside(x,y))
b1=true;
else
b1=false;
repaint();
return true;
}
public void paint(Graphics g)
{
if(waitMessage)
{ g.setColor(Color.blue);
g.drawString("Loading images, please wait...",200,100);
loadGraphics();
}
else
{
drawPanel();
g.drawImage (Buffer,0,0, this);
}
}
}
//< code ="Slideshow" height ="500" width="500">
//< /applet>

Ps: This program works fine, errors if any kindly leavea comment...

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The Life Cycle of an Applet

The Life Cycle of an Applet :

Loading the Applet
When an applet is loaded, here's what happens:

* An instance of the applet's controlling class (an Applet subclass) is created.
* The applet initializes itself.
* The applet starts running.


Leaving and Returning to the Applet's Page
When the user leaves the page -- for example, to go to another page -- the applet has the option of stopping itself. When the user returns to the page, the applet can start itself again. The same sequence occurs when the user iconifies and then reopens the window that contains the applet. (Other terms used instead of iconify are minaturize, minimize, and close.)

Reloading the Applet
Some browsers let the user reload applets, which consists of unloading the applet and then loading it again. Before an applet is unloaded, it's given the chance to stop itself and then to perform a final cleanup, so that the applet can release any resources it holds. After that, the applet is unloaded and then loaded again.

Quitting the Browser
When the user quits the browser (or whatever application is displaying the applet), the applet has the chance to stop itself and do final cleanup before the browser exits.

 

SummaryAn applet can react to major events in the following ways:
1. It can initialize itself.
2. It can start running.
3. It can stop running.
4. It can perform a final cleanup, in preparation for being unloaded.

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Vertical Scroll a Shape

/* Java Program To Move a Shape say Oval from the bottom of the applet to the center, a vertical scroll in an infinite loop ie once the shape reaches the denter it goes back to the bottom and repeats the path */

import java.awt.*;
import java.applet.*;

public class VertiScroll extends Applet implements Runnable
{
int x,y;
Dimension size;

public void init()
{
//set initial co-ordinates for message
x = 230;
y = 450;
//creates new thread
Thread t = new Thread(this);
t.start();
}
public void run()
{
while (true)
{
try
{
/*initialize size to contain the current size of the applet window */

size = getSize();
/* if co-ordinate of the oval is lesser than reset the height of the applet the x coordinate to a value say 200 else decrement y */

if(y< 200)
y = 450;
y--;
Thread.sleep(20);
}
catch(InterruptedException e)
{
}
repaint();
}
}

public void paint(Graphics g)
{
g.setColor(Color.red);
g.fillOval(x,y,40,50);
}
}

/*< applet code=VertiScroll Width=500 Height = 500>< /applet>*/

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Horizontal Scroll Text - 2

/* Program In Java To Display A text and to scroll the text from left to right, display the text as colored */

import java.awt.*;
import java.applet.*;

public class HoriScroll2 extends Applet implements Runnable
{
String message = "Pay-Per-Play Starts on Feburary....";
int x,y;
Dimension size;

public void init()
{
//set initial co-ordinates for message
x = 300;
y = 50;
//creates new thread
Thread t = new Thread(this);
t.start();
}
public void run()
{
while (true)
{
try
{
/*initialize size to contain the current size of the applet window */

size = getSize();
/* if co-ordinate of the text is lesser than a value say 5 reset the width of the applet the x coordinate to 500 else decrement x */

if(x< 5)
x = 500;
x--;
Thread.sleep(50);
}
catch(InterruptedException e)
{
}
repaint();
}
}

public void paint(Graphics g)
{
g.setFont(new Font("Terminal",Font.BOLD|Font.ITALIC,26));
g.setColor(Color.green);
g.drawString(message,x,y);
}
}

/*< applet code=HoriScroll2 Width=500 Height = 500>< /applet>*/

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Horizontal Scroll Text

/* Program In Java To Display A text and to scroll the text from right to left, display the text as colored */

import java.awt.*;
import java.applet.*;

public class HoriScroll extends Applet implements Runnable
{
String message = "Lionel Cyril ....";
int x,y;
Dimension size;

public void init()
{
//set initial co-ordinates for message
x = 10;
y = 50;
//creates new thread
Thread t = new Thread(this);
t.start();
}
public void run()
{
while (true)
{
try
{
/*initialize size to contain the current size of the applet window */

size = getSize();
/* if co-ordinate of the text is greater than reset the width of the applet the x coordinate to 10 else increment x */

if(x>size.width)
x = 0;
x++;
Thread.sleep(50);
}
catch(InterruptedException e)
{
}
repaint();
}
}

public void paint(Graphics g)
{
g.setFont(new Font("Monotype Corsiva",Font.BOLD,24));
g.setColor(Color.red);
g.drawString(message,x,y);
}
}

/*< applet height="500" width="500" code="HoriScroll">< /applet>*/

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Grid Layout

/* Java Program To Make Use of grid layout to displaying components onto the applet. The Components Includes Buttons Text Boxes,Check Boxes. Done using Applets. */

import java.awt.*;
import java.applet.*;

public class GridApp extends Applet
{
TextArea ta;
TextField tf;
Button b1,b2;
CheckboxGroup cbg;
Checkbox cb1,cb2,cb3,cb4;
GridBagLayout gb;
GridBagConstraints gbc;

public void init()
{
gb = new GridBagLayout();
setLayout(gb);
gbc = new GridBagConstraints();
ta = new TextArea("TextArea",5,10);
tf = new TextField("Enter your Name:");
b1 = new Button ("TextArea");
b2 = new Button ("TextField");
cbg = new CheckboxGroup();
cb1 = new Checkbox("Bold",cbg, false);
cb2 = new Checkbox("Italic",cbg,false);
cb3 = new Checkbox("Plain",cbg,false);
cb4 = new Checkbox("Bold/Italic",cbg,true);

gbc.fill = GridBagConstraints.BOTH;
addComponent(ta,0,0,4,1);
gbc.fill = GridBagConstraints.HORIZONTAL;
addComponent(b1,0,1,1,1);
gbc.fill = GridBagConstraints.HORIZONTAL;
addComponent(b2,0,2,1,1);
gbc.fill = GridBagConstraints.HORIZONTAL;
addComponent(cb1,2,1,1,1);
gbc.fill = GridBagConstraints.HORIZONTAL;
addComponent(cb2,2,3,1,1);
gbc.fill = GridBagConstraints.HORIZONTAL;
addComponent(cb3,1,1,1,1);
gbc.fill = GridBagConstraints.HORIZONTAL;
addComponent(cb4,3,2,1,1);
gbc.fill = GridBagConstraints.HORIZONTAL;
addComponent(tf,4,0,1,3);
}
public void addComponent(Component c, int row, int col, int nrow, int ncol)
{
gbc.gridx = col;
gbc.gridy = row;
gbc.gridwidth = ncol;
gbc.gridheight = nrow;
gb.setConstraints(c,gbc);
add(c);
}
}
//< applet code =GridApp width = 500 height = 500>< /applet>

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Flow Layout

/* Java Program On Flow Layout. The Components Inclues Buttons, TextField, label. Done using Applets.*/

import java.awt.*;
import java.applet.*;

public class FlowApp extends Applet
{
public void init()
{
TextField t1 = new TextField(20);
Label l1 = new Label ("Name");
Button b = new Button("OK");
TextField t2 = new TextField(20);
Label l2 = new Label ("Name");
Button b1 = new Button("OK");
add(l1);
add(t1);
add(b);
add(l2);
add(t2);
add(b1);
}}

//< applet code =FlowApp width = 500 height = 500>< /applet>

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Button Display

/* Java Program To Display Button On An Applet . Done using Applets.*/

import java.awt.*;
import java.applet.*;

public class BorderApp extends Applet
{
public void init()
{
setLayout(new BorderLayout());
Button b1 = new Button("EAST");
Button b2 = new Button("WEST");
Button b3 = new Button("NORTH");
Button b4 = new Button("SOUTH");
Button b5 = new Button("CENTER");
add("East",b1);
add("West",b2);
add("North",b3);
add("South",b4);
add("Center",b5);
}
}
//< applet code =BorderApp width = 500 height = 500>< /applet>

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Draw Image

/* Java Program To Draw Image on the applet. Done using Applets. */

import java.awt.*;
import java.applet.*;

public class AppletImage extends Applet
{
Image img;
public void init()
{
String imagename= getParameter("Whilder e Pool");
img = getImage(getCodeBase(),imagename);
}
public void paint(Graphics c)
{
c.drawImage(img,10,10,this);
}
}

//< applet code = AppletImage width = 770 Height = 555>
//< param name = "Whilder e pool " value = "madonnablue6bp.gif">
//< /applet>

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Color Program

/*Java Program To Display Simple Text on the applet, making use of Color class. Done using Applets. */

import java.awt.*;
import java.applet.*;

public class AppletColor extends Applet
{
public void paint(Graphics c)
{
setBackground(Color.blue);
c.setColor(Color.white);
c.drawString("Lionel Is a Cool Boy",100,50);
}
}

//< code =" AppletColor" width =" 350" height =" 150">< / applet >

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Java Program To Display A Human Face - Graphics

/*Program Displaying the human face suing basic figures, circles, arcs, lines, etc. Done using Applets.

/* < applet code = "Face" width = 500 height =500>
< /applet> */

import java.awt.*;
import java.applet.*;

public class Face extends Applet
{
public void paint(Graphics g)
{
g.drawString("Hi !!!!!!!!!!!!!!! I Am Ninad.",20,30);

g.drawArc(30,50,200,200,0,360); // Main Face
g.drawArc(82,80,30,30,20,160); //Left Eye Brow
g.fillArc(85,85,25,25,0,360); //Left Eye
g.drawArc(152,80,30,30,20,160); //Right Eye Brow
g.fillArc(155,85,25,25,0,360); //Right Eye
g.drawRect(90,190,80,20); //Mouth

g.drawLine(130,135,115,160); //Nose Left Line
g.drawLine(130,135,145,160); // Nose Right Line
g.drawLine(115,160,145,160); // Nose Base

g.drawString(" ------------- Created By Lionel.",10,350);
}
}

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Mobile Java

One of the nice things about Java is that is supported on more than desktop platforms, and has been for a long time. This means there is not only a large library of existing software, but also well-tuned development systems to use with mobile platforms.

By "mobile platform", I'm referring to smartphones and tablets. There are other mobile platforms, but these are the most common ones. Netbooks may also run a "mobile" operating system, or they may run a normal desktop OS. Those that run a normal desktop OS will run normal Java SE applications. Java SE is "Java, Standard Edition", the version that typically runs on a desktop or laptop computer.

Java ME is Java, Mobile Edition. It runs on most smartphones, and many tablets. It is very similar to the Java SE version covered in most of my articles. In fact, it is possible to write many applications using a subset of Java that will run without change under both Java SE and Java ME.

But normally a Java ME application will use user interface objects and interfaces that are specific to Java ME. In many ways these are more sophisticated than the ones for Java SE. Creating many types of graphical interfaces, such as tiled graphics, is easier in the mobile edition than in standard Java.

I have been writing small, simple applications for my cellphones for about ten years now. It's nice to be able to write your own little application for your own unique needs. I started writing Java applications for my Nokia 3650, called a "feature phone" at the time I got it. It was a Symbian Series 60 phone that ran an early version of Java ME with a very basic library of GUI features.

My next phone was a step up the Java ladder. It was a Sciphone G2, a fake Android phone. I didn't mind that it was "fake", it ran a real version of Java ME with updated GUI capabilities, which made it far easier to write applications for.

My current phone is a Blackberry Curve 8900. It runs Java ME with all the latest bells and whistles, plus a lot of Blackberry add-ons that make it easy to access the phone's features.

With my Nokia, I had a special Java development environment provided by Nokia that included a simulation of my phone, so that I could see how my programs would run before I put them on the phone. With the G2 I was on my own. I ran a standard Java ME development environment from within Eclipse, a great Java integrated development environment. The version linked above is a version specific to Java ME.

Now I'm back to having a development environment provided by my phone's maker. I have a program that simulates my phone on my computer, which again allows me to try out my programs before I put them on the phone (with my G2 I tested them as well as I could, then loaded them on the phone and hoped for the best.) It is build on Eclipse, so it is still very familiar. There is also a slew of information on the Blackberry site (linked above) about Java development.

Unfortunately, the tutorials on the site don't exactly match the actual current version of the software, but it's close enough it's not too hard to figure out. One thing that confused me, however, is the installation instructions. I thought I had to install the version of Eclipse they called for before installing the "Blackberry Java Eclipse Add-On". It's an add-on, right?

Well, it turns out that the "add-on" from Blackberry is actually the entire thing, Eclipse and all. So you just need to do that one download to get the development environment. Then download the simulator for your phone and any others you want to test your software on. Finally, apply for a signature key to make it so that you can "sign" your software to allow it to be installed on the phone through the software manager or Over The Air (OTA) when using the Blackberry-specific libraries.

If you'd rather not do this, you can develop software using a plain-jane version of Java ME, then transfer the software to your phone however you please. I put the software I developed for my Sciphone G2 on the memory card for my Blackberry, and it runs just fine.

Translating applications between Java SE and Java ME can be simple for ones with minimal amounts of graphics, like programs that mainly use text, buttons, and text entry boxes for communication. Things like games, with a more involved use of graphics, take more effort to translate between the two versions of Java. For these, I usually re-use the game logic code without changes, then rewrite the graphical display parts of the program from scratch. Because I use good object-oriented coding practices (most of the time), this isn't too much effort.

Java ME applets are easy to translate, though I write almost all of my Java software as applications now.

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main ()

There are two basic types of Java programs: applets and applications.* Applets run through a browser or a special program called AppletViewer. Applications are stand-alone programs that run on the same system they're stored on, like most traditional programs. Since there's lots of information elsewhere on applets, we'll concern ourselves mostly with applications.

Every application has a special method called main(). The main() method marks the starting point in the program for the Java Virtual Machine. Here's a short example program:

public class Hello{

public static void main(String arg[]){

System.out.println("Hello");

}

}

When this program is compiled using javac then run with the command

>java Hello
the JVM loads Hello.class and looks in it for the main() method, then starts executing the code inside main()'s code block.

Now, you'll notice there's a bunch of other stuff with main():

public static void main(String arg[]){

Because of how Java works, that stuff has to be there in a Java application. You can't just put "main(){" on the line by itself. The other stuff has a purpose, though it all looks very confusing, and certainly it looks like a lot of extra junk in a short program.

public allows the method to be accessed from outside the class (and its package--we'll get into that later.) If you leave out public, the JVM can't access main() since it's not available outside of Hello.

static says that this is the one and only main() method for this entire class (or program). You can't have multiple main()s for a class. If you leave static out, you'll get an error.

void says that main() doesn't pass back any data. Since the JVM wouldn't know what to do with any data, since it's not set up to accept data from main(), main() has to be of type void, which is to say that it's a method that doesn't pass any data back to the caller. If you leave this out main() won't have a data type, and all methods have to have a data type, even if it's void.

Inside main()'s parentheses is String arg[]. This is a way for the program to accept data from the host system when it's started. It's required that main() be able to accept data from the system when starting. And the data must be in the form of an array of Strings (or a variable-length list of Strings as of Java 5, but that's something we'll save for later.) The name "arg" can be whatever you want to make it. It's just a name I've given the array. It could just as well be:

public static void main(String fred[]){

I'd just have to be sure to use fred whenever I wanted to access the information that the system has passed to my application when it started, instead of arg.

Finally, after the parentheses, comes the open curly brace { that marks the start of main()'s code block.

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