I am totally new in Java.

I want to learn java. But I dont know how can i Do that. I also dont know which software i have to download. Which one is better for me as a new learner. Please some one help me.

Here are some links for your browser.
Free Tutorials and Such
Installation Notes - JDK 5.0 Microsoft Windows (32-bit)
Your First Cup of Java
The Java? Tutorial - A practical guide for programmers
New to Java Center
Java Programming Notes - Fred Swartz
How To Think Like A Computer Scientist
Introduction to Computer science using Java
The Java Developers Almanac 1.4
Object-Oriented Programming Concepts
Object-oriented language basics
Don't Fear the OOP
Free Java Books
Thinking in Java, by Bruce Eckel (Free online)
Core Servlet Programming, by Merty Hall (Free Online)
More Servlets, by Marty Hall (Free Online)
A Java GUI Programmer's Primer
Data Structures and Algorithms
with Object-Oriented Design Patterns in Java, by Bruno R. Preiss
Introduction to Programming Using Java, by David J. Eck
Advanced Programming for the Java 2 Platform
The Java Language Specification
Have fun
JJ

Similar Messages

Totally New in Java - Please help!!

Hi Dear all,
l am totally new in Java, and l facing one problem,and really hope can get some help from yours,please!
l need to write this program:
The program should do the following:
1. Input two fields: action (action: add / delete), and account number (any
digit or character)
2. if the action is "add" then the program adds one text line to a text
file.
"New account is <account number>"
3. create the text file if it is not already exist (in c:\)
4. When program runs again with new input values, a new line will be
appended to the same file.
5. if the action is "delete" then the program finds the record and removes
the text line from the file.
My problem is :
l just know that l need to create the user interface first,but l don't know how to go on??
Would you please show me some step how to solve these problem?
Many many thanks!!
BaoBao

I don't know about Swing. I never use it.
The stuff to create and manipulate files is in the java.io package.
You'll probably want to use java.io.FileReader and java.io.FileWriter.
Note that FileWriter has a constructor that lets you append and not overwrite.
I'll start you off with a test.
public class AccountListAddTest() {
public static void main(String[] argv) {
AccountList accts = new AccountList();
accts.add("abcdefg12345"); // arg is a hypothetical account number
}Write an AccountList class that'll work if you compile and run this test. After you run this test for the first time, the file should contain the string
New account is abcdefg12345.
This test assumes that the filename is hardcoded into the AccountList class. To keep it simple, make the add method create a new appending FileWriter each time, write, then close the writer.

Pls help, i m totally new to java

Hi everyone, i m new to java, i have created a page with a textfield and two buttons, can someone tell me how to pass the text that i input in the text field into my database (mysql) when i click the add button (id:addButton) and then how to retrieve a data from a column of my database when i click the show button (id:showButton)?
my table name is todolist3 and the column in my database is item.
Thank you very much!!!

if u are completly new to java, u must at least read some tutorials about java and later, the tutorial of Java Studio Creator, and if u have time, something about jsp.
i dont want to be rude, but listen my advice, if u want to make your "example" to work, u need to copy the mysql conector into core, this is inside of creator, create a data source to bind your project to mysql table, and the best part, send and receive data from your mysql database.
any doubt just post again
Belthazor

Totally new to java

Hi i`m am such a newbie to java and am struggling to get it running on my pc. What i have done is this: DL the JDK update 10: DL Crimson Editor: i have gone into my enviroment variables and placed C:\Program Files\Java\jdk1.6.0_10\bin at the path variable and user variable. I also place at the classpath a ( . ) in the value field. so now when i try to run a small welcome program i got from the university - i get:
C:\>java code
Exception in thread "main" java.lang.NoClassDefFoundError: code
Caused by: java.lang.ClassNotFoundException: code
at.java.net.URLClassLoader$1.run<URLClassLoader.java:200>
at.java.security.AccessController.doPrivileged<Native Method>
at.java.net.URLClassLoader.findClass<URLClassLoader.java:188>
at.java.lang.ClassLoader.LoadClass<ClassLoader.java:307>
at.sun.misc.Launcher$AppClassLoader.LoadClass<Launcher.java:301>
at.java.lang.ClassLoader.LoadClass<ClassLoader.java:252>
at.java.lang.ClassLoader.LoadClassInternal<ClassLoader.java:320>
Could not find the main class: code. Program will exit.
C:\>javac java code
error: Class names, 'java,code' are only accepted if annotation processing is explicitly requested
1 error
c:\
Why is this happening - i have tried to step by step walkthrough but i still dont seem to get it right.
remember i am so so so new to programing its all very strange to me but i want to learn. Help me please.
Bulldog1965

bulldog1965 wrote:
Hi i`m am such a newbie to java and am struggling to get it running on my pc. What i have done is this: DL the JDK update 10: DL Crimson Editor: i have gone into my enviroment variables and placed C:\Program Files\Java\jdk1.6.0_10\bin at the path variable and user variable. I also place at the classpath a ( . ) in the value field. so now when i try to run a small welcome program i got from the university - i get:
C:\>java code
Exception in thread "main" java.lang.NoClassDefFoundError: code
Caused by: java.lang.ClassNotFoundException: code
at.java.net.URLClassLoader$1.run<URLClassLoader.java:200>
at.java.security.AccessController.doPrivileged<Native Method>
at.java.net.URLClassLoader.findClass<URLClassLoader.java:188>
at.java.lang.ClassLoader.LoadClass<ClassLoader.java:307>
at.sun.misc.Launcher$AppClassLoader.LoadClass<Launcher.java:301>
at.java.lang.ClassLoader.LoadClass<ClassLoader.java:252>
at.java.lang.ClassLoader.LoadClassInternal<ClassLoader.java:320>
Could not find the main class: code. Program will exit.
C:\>javac java code
error: Class names, 'java,code' are only accepted if annotation processing is explicitly requested
1 erroryou are supposed to specify the name of the java file, eg.
javac Hello.java
where Hello.java is a file containing some class which has a method main declared to be public and static and
having parameter of type String[]
>
c:\
Why is this happening - i have tried to step by step walkthrough but i still dont seem to get it right.
remember i am so so so new to programing its all very strange to me but i want to learn. Help me please.
Bulldog1965

Totally New to RMI, need help and advice.

Hi, all experts.
I am totally new in Java RMI. When I run a sample RMI application, still got problem.
Please give me some advice or recommend some basic materials for me to catch up.
Appreciate for you help. I need to finish one RMI project in a short period.
best regards,
Xiong Fei

The Java tutorials are usually a good place to start. Try: http://java.sun.com/docs/books/tutorial/rmi

New to Java EE 5

hi everyone,
i'm totally new to Java EE...i had used J2SE before to develop desktop applications (and with Swing for GUI too)...and i also used J2SE along with Tomcat to develop some simple web development...
now i'm going to get into a bigger Java web development project...and i would like to know more about Java EE and other technologies surrounding it...it'd be great if some of you can help =)
1) do i need Java EE instead of Java SE for web development? i ask because before i did some simple JSP/Servlet stuff with only J2SE SDK and Tomcat...
2) what is the purpose of Glassfish? i read that it is an application server...what is an application server for? what is the purpose of Glassfish over Java EE SDK/JRE?
3) for web development in Java, which IDE should i use? Eclipse or NetBeans? what are their pros and cons?
4) i know in these years, there are several popular java frameworks for web development such as Struts, Spring, etc...now for Java EE 5, what would be a good framework to use? Would JSF be the right direction to go as it is a framework from Sun?
hmm...i still have a lot more questions....but i'll limit the number of questions in this post...
thank you for your time and information!! =)

1) do i need Java EE instead of Java SE for web
development? i ask because before i did somesimple
JSP/Servlet stuff with only J2SE SDK and Tomcat...You need Java EE with Java SE, not instead. you mean i need both of them installed? what is the procedure? like if i go to the following link for the SDK of Java EE 5...i still need to go to download SE and install it?
http://java.sun.com/javaee/downloads/index.jsp
>
Tomcat is a web container and it has the
implementation of the servletjsp classes which are
available in EE.
2) what is the purpose of Glassfish? i read thatit
is an application server...what is an application
server for? what is the purpose of Glassfish over
Java EE SDK/JRE?Glassfish is an application server which is used for
web applications (web container) as well as
enterprise components like EJB.so Glassfish is a counterpart of Tomcat? like i can use Glassfish instead of Tomcat? how about Apache? i have been using Apache as the web server whilte Tomcat being the app server...how does Glassfish integrate with Apache? or what web server should i use with Glassfish?
>
3) for web development in Java, which IDE should i
use? Eclipse or NetBeans? what are their pros and
cons?If you are going to use Glassfish, Netbeans would be
a better choice because it integrates well. For all
other application servers, I prefer Eclipse because I
don't know how to configure Netbeans and I have been
using Eclipse for a long time. The choice of IDE is
more of personal ease of use rather than actual
feature comparison.i don't know whether i should use Glassfish...it seems to me that it is expanding...and as i only had very little experience with Tomcat...switching to Glassfish would not be a waste of extra time for me...should i go with Glassfish then? or Tomcat is still considered more stable/reliable/compatible?
also...if Eclipse is good in other stuff...is it a good idea to find out more about Eclipse's support to Glassfish instead of going for NetBeans?
>
4) i know in these years, there are severalpopular
java frameworks for web development such asStruts,
Spring, etc...now for Java EE 5, what would be agood
framework to use? Would JSF be the right directionto
go as it is a framework from Sun?I haven't ever used JSF to comment on that but I
would suggest that you use Spring for good and clean
development.i understand this...as JSF is still quite new and developers have been using Struts and Spring forever...

Totally new - help please.

Good day everyone
I am totally new to Java, but eager to learn. Could you please provide me with info, leads etc. to get up and running ASAP? Where are the best tutorials (free download), where can I find good examples? I am planning to learn J2EE, as I am into building websites(also just started).
Regards
Adriaan.

Assuming you've already got a development environment ( JDK possibly editor or IDE ) there are lots of free tutorials here:
http://developer.java.sun.com/developer/onlineTraining/
If you get any problems, a top tip is to search these forums before you ask your question, as being a beginner, someone is bound to have had the same problem, and solved it already.

Very New to Jave, need to do totals/subtotals

Hi, (I hope this is the right place)
I'm VERY new to Java (I mainly do wourk with php interfaces for MyAQL databases).
Up until now, there hasn't been anything I couldn't do with PHP that I needed to...
My boss recently requested subtotals/totals at various points on an input sheet. The sheet inputs numbers of people, so I'm not worried about rounding (The php already takes care of people trying to input parts of people....) or tax.
It's a rather large form (~144 lines) and the math is already in place to do the subtotaling (among other things) before entering the information into the database.
How would I go about writing script that would display sub totals, and recalculate them every time one of the boxes value's is modified?
Is this something javascript is designed to do? Is there a better language out there for this task?
I've found sites out there that have canned subtotal/total scripts, but I don't want something pre-made unless it comes with a detailed explaination of what everything does; if I'm going to maintain it, I have to understand it.
Thanks

Is this a web form? e.g. a html form with input fields?
You can add onchange or onblur events to your input fields to detect changes. Then you can use javascript to retrieve the values from the form and do the calculation.
-S

New to JAVA, but old school to programming

Objects & Classes & Methods, Oh my!
I'm pretty new to java, but I've been programming in several languages over the years. I thought it was about time to update my skill set, especially with the job market as it is today. I wanted to go JAVA because it's not specific to any environment.
I picked up a begining JAVA book and was a little confused. When I was learning programming a program was called a program. a peice of code in a program called by a statement was called a subroutine (it was performed then control returned to the calling line and continued).
Now I'm trying to make sense of everything I have read so far and trying to relate it back to my old school of thinking. I was hoping it would make it easier to retain and I could expand it as I learn and possibly realize that it IS different. I know it's a new way of thinking, but stay with me for minute.
What I used to call a program is now a CLASS in JAVA (this can be a collection of code or other objects). A sub-routine in a CLASS is a Method. I know that the language part will come as I use it since I understand if's then's and whatever you use to gosub or goto, but I want to make sure I have down the lingo before I go to deep.

I have no idea how you can compare Java to Cobol.
DataFlex? How about that! In about '84 I switched to
DataFlex from dBaseII. In '91 DataFlex changed from
procedural to OOP. It took most of us at least a year
to adjust, and then some to write concrete code. It
was tough. They had bugs and we were limited with DOS.
BUT, it was a great OOP training experience. Anyhow,
needless to day Java is miles ahead on all fronts.Small world. I was stuck in the old DataFlex Ver 2.3 at that time. The company I worked for had the newer OOP package. I did get to work with it some, but not enough to become totally familiar with it. We started to move out of DataFlex towards PowerBuilder towards the end of 1995. I did get some OOP from that experience, but again only enough to learn about global variables, instance variables, and a few other items. I hoping that I will be able to get the solid OOP background that I need from JAVA since I hear through the grapevine that it may be a new tool that we will be looking at to enhance our programming. I was looking at PERL but even the PERL programmers we have agree that JAVA is more scalable.

New to Java and need help with this program..please!

I'd really appreciate any helpful comments about this program assignment that I have to turn in a week from Friday. I'm taking a class one night a week and completely new to Java. I'd ask my professor for help, but we can't call him during the week and he never answers e-mails. He didn't tell us how to call from other classes yet, and I just can't get the darn thing to do what I want it to do!
The assignment requirements are:
1. Change a card game application that draws two cards
and the higher card wins, to a Blackjack application
2. Include a new class called Hand
3. The Hand class should record the number of draws
4. The application should prompt for a number of draws
5. The game is played against the Dealer
6. The dealer always draws a card if the dealer's hand total is <= 17
7. Prompt the player after each hand if he wants to quit
8. Display the total games won by the dealer and total and the total games wond by the player after each hand
9. Display all of the dealer's and player's cards at the
end of each hand
10. Player has the option of drawing an additional card after the first two cards
11. The Ace can have a value of 11 or 1
(Even though it's not called for in the requirements, I would like to be able to let the Ace have a value of 1 or an 11)
The following is my code with some comments about a few things that are driving me nuts:
import java.util.*;
import javax.swing.*;
import java.text.*;
public class CardDeck
public CardDeck()
deck = new Card[52];
fill();
shuffle();
public void fill()
int i;
int j;
for (i = 1; i <= 13; i++)
for (j = 1; j <= 4; j++)
deck[4 * (i - 1) + j - 1] = new Card(i, j);
cards = 52;
public void shuffle()
int next;
for (next = 0; next < cards - 1; next++)
int rand = (int)(Math.random()*(next+1));
Card temp = deck[next];
deck[next] = deck[rand];
deck[rand] = temp;
public final Card draw()
if (cards == 0)
return null;
cards--;
return deck[cards];
public int changeValue()
int val = 0;
boolean ace = false;
int cds;
for (int i = 0; i < cards; i++)
if (cardValue > 10)
cardValue = 10;
if (cardValue ==1)     {
ace = true;
val = val + cardValue;
if ( ace = true && val + 10 <= 21 )
val = val + 10;
return val;
public static void main(String[] args)
CardDeck d = new CardDeck();
int x = 3;
int i;
int wins = 1;
int playerTotal = 1;
do {
Card dealer = (d.draw());
/**I've tried everything I can think of to call the ChangeValue() method after I draw the card, but nothing is working for me.**/
System.out.println("Dealer draws: " + dealer);
do {
dealer = (d.draw());
System.out.println(" " + dealer);
}while (dealer.rank() <= 17);
Card mine = d.draw();
System.out.println("\t\t\t\t Player draws: "
+ mine);
mine = d.draw();
System.out.println("\t\t\t\t\t\t" + mine);
do{
String input = JOptionPane.showInputDialog
("Would you like a card? ");
if(input.equalsIgnoreCase("yes"))
     mine = d.draw();
System.out.println("\t\t\t\t\t\t" + mine);
     playerTotal++;
     else if(input.equalsIgnoreCase("no"))
System.out.println("\t\t\t\t Player stands");
     else
System.out.println("\t\tInvalid input.
Please try again.");
I don't know how to go about making and calling a method or class that will combine the total cards delt to the player and the total cards delt to the dealer. The rank() method only seems to give me the last cards drawn to compare with when I try to do the tests.**/
if ((dealer.rank() > mine.rank())
&& (dealer.rank() <= 21)
|| (mine.rank() > 21)
&& (dealer.rank() < 22)
|| ((dealer.rank() == 21)
&& (mine.rank() == 21))
|| ((mine.rank() > 21)
&& (dealer.rank() <= 21)))
System.out.println("Dealer wins");
wins++;
     else
System.out.println("I win!");
break;
} while (playerTotal <= 1);
String stop = JOptionPane.showInputDialog
("Would you like to play again? ");
if (stop.equalsIgnoreCase("no"))
break;
if (rounds == 5)
System.out.println("Player wins " +
(CardDeck.rounds - wins) + "rounds");
} while (rounds <= 5);
private Card[] deck;
private int cards;
public static int rounds = 1;
public int cardValue;
/**When I try to compile this nested class, I get an error message saying I need a brace here and at the end of the program. I don't know if any of this code would work because I've tried adding braces and still can't compile it.**/
class Hand()
static int r = 1;
public Hand() { CardDeck.rounds = r; }
public int getRounds() { return r++; }
final class Card
public static final int ACE = 1;
public static final int JACK = 11;
public static final int QUEEN = 12;
public static final int KING = 13;
public static final int CLUBS = 1;
public static final int DIAMONDS = 2;
public static final int HEARTS = 3;
public static final int SPADES = 4;
public Card(int v, int s)
value = v;
suit = s;
public int getValue() { return value; }
public int getSuit() { return suit; }
public int rank()
if (value == 1)
return 4 * 13 + suit;
else
return 4 * (value - 1) + suit;
/**This works, but I'm confused. How is this method called? Does it call itself?**/
public String toString()
String v;
String s;
if (value == ACE)
v = "Ace";
else if (value == JACK)
v = "Jack";
else if (value == QUEEN)
v = "Queen";
else if (value == KING)
v = "King";
else
v = String.valueOf(value);
if (suit == DIAMONDS)
s = "Diamonds";
else if (suit == HEARTS)
s = "Hearts";
else if (suit == SPADES)
s = "Spades";
else
s = "Clubs";
return v + " of " + s;
private int value; //Value is an integer, so how can a
private int suit; //string be assigned to an integer?
}

Thank you so much for offering to help me with this Jamie! When I tried to call change value using:
Card dealer = (d.changeValue());
I get an error message saying:
Incompatible types found: int
required: Card
I had my weekly class last night and the professor cleared up a few things for me, but I've not had time to make all of the necessary changes. I did find out how toString worked, so that's one question out of the way, and he gave us a lot of information for adding another class to generate random numbers.
Again, thank you so much. I really want to learn this but I'm feeling so stupid right now. Any help you can give me about the above error message would be appreciated.

New to java - glitch in my program/game? should be a simple fix :)

hey everyone, I'm a student who's new to java programming :) It's is also the first programming language that I'm learning. I know the basics, but nothing very complicated.
I'm making a pong-like game, in an applet.
As I was making the paddle and using a mouselistener to make it move vertically, I came across this problem, the paddle will move vertically with the mouse's position, but one end of my paddle will grow abnormally (I want it to stay the same size as it moves up and down)
Here's my code: (I'm not using most of the mouselistener and keylistener classes yet, so you can ignore them. I'm guessing the problem is probably in one of the last classes, at the bottom)
ypaddle is the variable used for getting the co-ordinates of the mouse and transferring them to the paddle itself
// The "Ping" class.
import java.applet.*;
import java.awt.*;
import java.awt.event.*;
*Ping
public class Ping extends Applet
    implements KeyListener, MouseListener, MouseMotionListener
    int width, height, x, ypaddle;
    Graphics g;
    char move;
     *Initializes variables
    public void init ()
        resize (700, 500);
        setBackground (Color.white);
        addKeyListener (this);
        addMouseListener (this);
        addMouseMotionListener(this);
    public void keyPressed (KeyEvent e)
    public void keyReleased (KeyEvent e)
    public void keyTyped (KeyEvent e)
    public void mouseEntered (MouseEvent e)
    public void mouseExited (MouseEvent e)
    public void mousePressed (MouseEvent e)
    public void mouseReleased (MouseEvent e)
    public void mouseClicked (MouseEvent e)
    public void mouseMoved (MouseEvent e)
        ypaddle = e.getY ();
        repaint();
    public void mouseDragged (MouseEvent e)
    public void paint (Graphics g)
        paddle (g, ypaddle);
     * Creates the paddle for hitting the ball
     *@param    y   value used to move the paddle vertically
    public void paddle (Graphics g, int y)
        g.fillRect (10, 10+y, 15, 60+y);
} // Ping classI'm totally stumped, I've tried for 2 hours to find the problem, and I have a feeling it's something very simple that I'm passing over...
If you have any questions about the variables or other things, please ask!
And one last little quick question, is there a way I can restrict the movement of the paddle between two Y values? (i.e not higher than y=10 or lower than y=100)
Thanks in advance :)

soundweave wrote:
I'm not exactly sure how to find out, Eh?
You wrote this code:
g.fillRect (10, 10+y, 15, 60+y);Do you understand what fillRect does? If I call fillRect(10, 20, 30, 40) where will that rectangle be drawn? If you don't know how to answer that, I don't see how you could have written that line of code.
but here's some pictures of what happens ( I put in 0 and 80 as the y values in each picture, and left the code window open so you can see )I don't need to see them.
Y at 0: [http://i731.photobucket.com/albums/ww314/len56/Untitled.jpg?t=1263077701|http://i731.photobucket.com/albums/ww314/len56/Untitled.jpg?t=1263077701]
Y at 80: [http://i731.photobucket.com/albums/ww314/len56/Untitled2.jpg?t=1263077625|http://i731.photobucket.com/albums/ww314/len56/Untitled2.jpg?t=1263077625]
So, given that the first one comes from fillRect(10, 10, 15, 60), (you get where that comes from I hope) and the second comes from fillRect(10, 90, 15, 150) (that too), does that not suggest that something is wrong with the numbers you're passing to fillRect? And since you have read the docs for fillRect and know what it does and what each of its parameters represents (right?), does it not suggest exactly what is wrong with those numbers?

Very new to java please help

i'm very new to java and i'm getting an error in my application. i took 4 applications that compiled and worked separatly and i tried to combine them into one application. i'm getting the error: unreported exception java.io.IOException; must be caught or declared to be thrown, in lines 73,78,83,88,120,146,149,152,155 in the and it points at the keyboard.readLine() but everything i've tried just gives me more errors. please help anything and everything will be greatly appreciated. here it is, sorry about format i dunno how to straighten it in here:
// ^ ^
//               (0)(0) A Happy Piggy Application
// Problems: 2.6,2.8,2.9,2.12 (oo)
// An application finds the total number of hours, minutes, & seconds, finds the distance
// between two points, finds the volume and surface area of a sphere, and adds up the change
// in a jar. First, the total hours, minutes, and seconds problem.
import java.io.*;
import java.text.DecimalFormat;
import java.text.NumberFormat;
public class twoptsix
     static BufferedReader keyboard = new BufferedReader(new InputStreamReader(System.in));
     static PrintWriter screen = new PrintWriter(System.out, true);
     public static void main (String[] args) throws IOException
          double hoursa, minutesa, secondsa;
          String hours;
          System.out.print ("Please enter a number of hours: ");
hours = keyboard.readLine();
hoursa = Double.parseDouble(hours); //asks programmer friendly user to enter hours
String minutes;
System.out.print ("Please enter a number of minutes: ");
minutes=keyboard.readLine();
minutesa = Double.parseDouble(minutes); //asks programmer friendly user to enter minutes
String seconds;
System.out.print ("Pretty please enter a number of seconds: ");
seconds = keyboard.readLine();
secondsa = Double.parseDouble(seconds); //asks programmer friendly user to enter seconds
double allseconds;
allseconds = (hoursa * 3600) + (minutesa * 60) + secondsa; //adds up all the seconds of the time entered
System.out.println ("You have: " + hours + " hours..."); //displays hours
System.out.println ("" + minutes + " minutes..."); //displays minutes
System.out.println ("and " + seconds + " seconds..."); //displays seconds
          System.out.println ("to get whatever you need to done!"); //witty attempt at humor
System.out.println ("The total amount of seconds is: " + allseconds + " seconds."); //displays total seconds
// An application that finds the distance between two points when the points
// are given by the user.
          double x1, x2, y1, y2, total, distance;
          String xa;
          System.out.print ("Please enter the 'x' coordinate of first point: ");
          xa = keyboard.readLine();
          x1 = Double.parseDouble(xa); //asks programmer friendly user to enter first x value
          String ya;
          System.out.print ("...also need the 'y' coordinate of first point: ");
          ya = keyboard.readLine();
          y1= Double.parseDouble(ya); //asks programmer friendly user to enter first y value
          String xb;
          System.out.print ("...and the 'x' coordinate of the second point: ");
          xb = keyboard.readLine();
          x2 = Double.parseDouble(xb); //asks programmer friendly user to enter second x value
          String yb;
          System.out.print ("...don't forget the 'y' coordinate of the second point: ");
          yb = keyboard.readLine();
          y2 = Double.parseDouble(yb); //asks programmer friendly user to enter second y value
          total = Math.pow(x2 - x1, 2.0) + Math.pow(y2 - y1, 2.0); //squares the differences of values
          distance = Math.sqrt(total); //finds the square root of the sum of the differences of the values
          System.out.print ("E=mc^2...oh and,");
          System.out.print ("the distance between point (" + xa +"," + ya +") and point("+
          xb + "," + yb + ") is : " + distance);
// An application that takes the radius of a sphere and finds and prints
// the spheres volume and surface area.
          double radius,volume,area;
          String rad;
          System.out.print("Please enter the radius of a sphere: ");
          rad = keyboard.readLine();
          radius = Double.parseDouble(rad); //asks programmer friendly user to enter the radius of a sphere
DecimalFormat fmt = new DecimalFormat ("0.####");
          volume = ((4 * Math.PI * Math.pow(radius,3.0)) / 3) ;
          System.out.println (" The sphere has a volume of:" + fmt.format(volume)); //finds and displays volume
          area = ( 4 * Math.PI * Math.pow(radius, 2.0)) ;
          System.out.print (" The Surface Area of the sphere is: " + fmt.format(area)); //finds and displays surface area
// An application that finds the total, in dollars and cents, of a number of quarters,
// nickels, dimes, and pennies in your piggy bank.
          int pennies, nickels, dimes, quarters;
          double money1;
          screen.println("Empty your piggy bank and count the change, how many quarters ya have?: ");
          int q = (new Integer(keyboard.readLine())).intValue();//asks programmer friendly user to enter a number of quarters
          screen.println("How many dimes?: ");
          int d = (new Integer(keyboard.readLine())).intValue();//asks programmer friendly user to enter a number of dimes
          screen.println("How many nickels?: ");
          int n = (new Integer(keyboard.readLine())).intValue();//asks programmer friendly user to enter a number of nickels
          screen.println("How many pennies?: ");
          int p = (new Integer(keyboard.readLine())).intValue();//asks programmer friendly user to enter a number of pennies
          NumberFormat money = NumberFormat.getCurrencyInstance();
          money1 = (.25 * q) + (.1 * d) + (.05 * n) + (.01 * p);
          screen.println("You're rich! Total, you've got: " + money.format(money1));//finds and displays total money

Ok here is the working code as one long function:
// ^ ^
// (0)(0) A Happy Piggy Application
// Problems: 2.6,2.8,2.9,2.12 (oo)
// An application finds the total number of hours, minutes, & seconds, finds the distance
// between two points, finds the volume and surface area of a sphere, and adds up the change
// in a jar. First, the total hours, minutes, and seconds problem.
import java.io.*;
import java.text.DecimalFormat;
import java.text.NumberFormat;
public class twoptsix
    static BufferedReader keyboard = new BufferedReader(new InputStreamReader(System.in));
    static PrintWriter screen = new PrintWriter(System.out, true);
    public static void main (String[] args) throws IOException
double hoursa, minutesa, secondsa;
String hours;
System.out.print ("Please enter a number of hours: ");
hours = keyboard.readLine();
hoursa = Double.parseDouble(hours); //asks programmer friendly user to enter hours
String minutes;
System.out.print ("Please enter a number of minutes: ");
minutes=keyboard.readLine();
minutesa = Double.parseDouble(minutes); //asks programmer friendly user to enter minutes
String seconds;
System.out.print ("Pretty please enter a number of seconds: ");
seconds = keyboard.readLine();
secondsa = Double.parseDouble(seconds); //asks programmer friendly user to enter seconds
double allseconds;
allseconds = (hoursa * 3600) + (minutesa * 60) + secondsa; //adds up all the seconds of the time entered
System.out.println ("You have: " + hours + " hours..."); //displays hours
System.out.println ("" + minutes + " minutes..."); //displays minutes
System.out.println ("and " + seconds + " seconds..."); //displays seconds
System.out.println ("to get whatever you need to done!"); //witty attempt at humor
System.out.println ("The total amount of seconds is: " + allseconds + " seconds."); //displays total seconds
// } <----- MAIN FUNCTION USED TO END HERE!!!
//but we want to keep going so remove the bracket!
// An application that finds the distance between two points when the points
// are given by the user.
// { <-- other function used to start here, but now it continues
double x1, x2, y1, y2, total, distance;
String xa;
System.out.print ("Please enter the 'x' coordinate of first point: ");
xa = keyboard.readLine();
x1 = Double.parseDouble(xa); //asks programmer friendly user to enter first x value
String ya;
System.out.print ("...also need the 'y' coordinate of first point: ");
ya = keyboard.readLine();
y1= Double.parseDouble(ya); //asks programmer friendly user to enter first y value
String xb;
System.out.print ("...and the 'x' coordinate of the second point: ");
xb = keyboard.readLine();
x2 = Double.parseDouble(xb); //asks programmer friendly user to enter second x value
String yb;
System.out.print ("...don't forget the 'y' coordinate of the second point: ");
yb = keyboard.readLine();
y2 = Double.parseDouble(yb); //asks programmer friendly user to enter second y value
total = Math.pow(x2 - x1, 2.0) + Math.pow(y2 - y1, 2.0); //squares the differences of values
distance = Math.sqrt(total); //finds the square root of the sum of the differences of the values
System.out.print ("E=mc^2...oh and,");
System.out.print ("the distance between point (" + xa +"," + ya +") and point("+
     xb + "," + yb + ") is : " + distance);
//second function used to end here...
//} <--- COMMENT OUT BRACKET SO WE CONTINUE
// An application that takes the radius of a sphere and finds and prints
// the spheres volume and surface area.
//{ <--- ANOTHER ONE TO COMMENT OUT
double radius,volume,area;
String rad;
System.out.print("Please enter the radius of a sphere: ");
rad = keyboard.readLine();
radius = Double.parseDouble(rad); //asks programmer friendly user to enter the radius of a sphere
DecimalFormat fmt = new DecimalFormat ("0.####");
volume = ((4 * Math.PI * Math.pow(radius,3.0)) / 3) ;
System.out.println (" The sphere has a volume of:" + fmt.format(volume)); //finds and displays volume
area = ( 4 * Math.PI * Math.pow(radius, 2.0)) ;
System.out.print (" The Surface Area of the sphere is: " + fmt.format(area)); //finds and displays surface area
// } <----- COMMENTED OUT FOR THE SAME REASON
// An application that finds the total, in dollars and cents, of a number of quarters,
// nickels, dimes, and pennies in your piggy bank.
//{ <----AND ANOTHER
int pennies, nickels, dimes, quarters;
double money1;
screen.println("Empty your piggy bank and count the change, how many quarters ya have?: ");
int q = (new Integer(keyboard.readLine())).intValue();//asks programmer friendly user to enter a number of quarters
screen.println("How many dimes?: ");
int d = (new Integer(keyboard.readLine())).intValue();//asks programmer friendly user to enter a number of dimes
screen.println("How many nickels?: ");
int n = (new Integer(keyboard.readLine())).intValue();//asks programmer friendly user to enter a number of nickels
screen.println("How many pennies?: ");
int p = (new Integer(keyboard.readLine())).intValue();//asks programmer friendly user to enter a number of pennies
NumberFormat money = NumberFormat.getCurrencyInstance();
money1 = (.25 * q) + (.1 * d) + (.05 * n) + (.01 * p);
screen.println("You're rich! Total, you've got: " + money.format(money1));//finds and displays total money
}P.S. To make the code formatted better put [ code ] before and [ /code ] after. It's not perfect, but a little better...

Help needed, new to java programming

hi,
I have craeted a Frame with some check boxes and button called "button1".
Can anyone tell me how can i count the number of CHECKED check boxes so that when i press the button1 in my code it should display the result as number of checked check boxes divided by total number of check boxes. It should display the result in a textfield here RESULT textfield in my code
Thanks in advance ...i am sending the code i have written so far....
public class Frame extends java.awt.Frame {
    /** Creates new form Frame */
    public Frame() {
        initComponents();
        setSize(600, 600);
    /** This method is called from within the constructor to
     * initialize the form.
     * WARNING: Do NOT modify this code. The content of this method is
     * always regenerated by the Form Editor.
    private void initComponents() {
        buttonGroup1 = new javax.swing.ButtonGroup();
        checkbox1 = new java.awt.Checkbox();
        checkbox2 = new java.awt.Checkbox();
        checkbox3 = new java.awt.Checkbox();
        button1 = new java.awt.Button();
        textField1 = new java.awt.TextField();
        setLayout(null);
        addWindowListener(new java.awt.event.WindowAdapter() {
            public void windowClosing(java.awt.event.WindowEvent evt) {
                exitForm(evt);
        checkbox1.setLabel("checkbox1");
        add(checkbox1);
        checkbox1.setBounds(160, 50, 84, 20);
        checkbox2.setLabel("checkbox2");
        add(checkbox2);
        checkbox2.setBounds(160, 70, 84, 20);
        checkbox3.setLabel("checkbox3");
        add(checkbox3);
        checkbox3.setBounds(160, 90, 84, 20);
        button1.setLabel("button1");
        button1.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                button1ActionPerformed(evt);
        add(button1);
        button1.setBounds(150, 180, 57, 24);
        textField1.setText("Result");
        textField1.setName("Result");
        add(textField1);
        textField1.setBounds(260, 180, 44, 20);
        pack();
    private void button1ActionPerformed(java.awt.event.ActionEvent evt) {
        // Add your handling code here:
    /** Exit the Application */
    private void exitForm(java.awt.event.WindowEvent evt) {
        System.exit(0);
     * @param args the command line arguments
    public static void main(String args[]) {
        new Frame().show();
    // Variables declaration - do not modify
    private java.awt.Button button1;
    private javax.swing.ButtonGroup buttonGroup1;
    private java.awt.Checkbox checkbox1;
    private java.awt.Checkbox checkbox2;
    private java.awt.Checkbox checkbox3;
    private java.awt.TextField textField1;
    // End of variables declaration
}

Two problems in the code you repost-ed:
1. It lacks import statements.
2. There is an extraneous } at the end of the button1ActionPerformed method.
Correct them and it'll work fine. Posting the full source code:
import java.awt.Component;
import java.awt.Checkbox;
public class Frame extends java.awt.Frame
     /** Creates new form Frame */
     public Frame()
          initComponents();
      * This method is called from within the constructor to initialize the form.
      * WARNING: Do NOT modify this code. The content of this method is always
      * regenerated by the Form Editor.
     private void initComponents()
          checkbox1 = new java.awt.Checkbox();
          checkbox2 = new java.awt.Checkbox();
          checkbox3 = new java.awt.Checkbox();
          button1 = new java.awt.Button();
          textField1 = new java.awt.TextField();
          setLayout( null );
          addWindowListener( new java.awt.event.WindowAdapter()
               public void windowClosing( java.awt.event.WindowEvent evt )
                    exitForm( evt );
          checkbox1.setLabel( "checkbox1" );
          add( checkbox1 );
          checkbox1.setBounds( 120, 40, 84, 20 );
          checkbox2.setLabel( "checkbox2" );
          add( checkbox2 );
          checkbox2.setBounds( 120, 60, 84, 20 );
          checkbox3.setLabel( "checkbox3" );
          add( checkbox3 );
          checkbox3.setBounds( 120, 80, 84, 20 );
          button1.setLabel( "button1" );
          button1.addActionListener( new java.awt.event.ActionListener()
               public void actionPerformed( java.awt.event.ActionEvent evt )
                    button1ActionPerformed( evt );
          add( button1 );
          button1.setBounds( 50, 170, 57, 24 );
          textField1.setText( "textField1" );
          add( textField1 );
          textField1.setBounds( 240, 170, 60, 20 );
          pack();
     private void button1ActionPerformed( java.awt.event.ActionEvent evt )
          // Add your handling code here:
          Component[] components = getComponents();
          int numOfCheckBoxes = 0;
          int numChecked = 0;
          for ( int i = 0; i < components.length; i++ )
               if ( components[i] instanceof Checkbox )
                    numOfCheckBoxes++;
                    Checkbox checkBox = (Checkbox) components;
                    if ( checkBox.getState() )
                         numChecked++;
          double ratio = (double) numChecked / (double) numOfCheckBoxes;
          textField1.setText( Double.toString( ratio ) );
     /** Exit the Application */
     private void exitForm( java.awt.event.WindowEvent evt )
          System.exit( 0 );
     * @param args the command line arguments
     public static void main( String args[] )
          new Frame().show();
     // Variables declaration - do not modify
     private java.awt.Button button1;
     private java.awt.Checkbox checkbox1;
     private java.awt.Checkbox checkbox2;
     private java.awt.Checkbox checkbox3;
     private java.awt.TextField textField1;
     // End of variables declaration
I can see from the code that the GUI was generated by a tool. Since you're new to Java programming, I'd recommend ditching the tool and writing everything by hand, otherwise you're not learning much. It's just like when you're learning proofs in Maths, where you start with first principles before making use of the proofs on their own.
Also, it'll help tremendously if you could spend some time going through the Java Tutorial (http://java.sun.com/docs/books/tutorial/). It's free, and I find it very useful.
Hth.

How can I calculate the total time in java?

Hello!
I need to calculate the total time!
For example I have start time:
          Format formatter1;
          Date date1 = new Date();
          formatter1 = new SimpleDateFormat("hh:mm:ss");
          String startTime = formatter1.format(date1);
          //startTime = "14:20:40";
And I have finish time:
          Format formatter2;
          Date date2 = new Date();
          formatter2 = new SimpleDateFormat("hh:mm:ss");
          String finishTime = formatter2.format(date2);
          //finishTime = "08:30:55";
So, after manually calculating, I get total time: "18:10:15"
How can I calculate the total time in java? (Using formatter1 and formatter2 I suppose)
What I need is to print "total 18:10:15"
Thanks!

800512 wrote:
I did the following but, I think something is wrong here:
I defined before: Date date1 = new Date(); Date date2 = new Date();
And it should be exactly 5 seconds between them.
I found delta between date1 and date2:
Format formatter = new SimpleDateFormat("HH:mm:ss");
          long timeInMilliFromStart = date1.getTime() - date2.getTime() ;
          Date date3 = new Date(timeInMilliFromStart);
          String timeInSecFromStart = formatter.format(date3);
and I get always
//timeInSecFromStart = 02:00:05
But it should be exactly 00:00:05.
What can be a problem?Because, like I said, a Date measure an instant in time, not a duration. So when you have 5000 ms, and you turn that into a Date, that means 5 sec. after the epoch, which works out to 1/1/1970 00:00:05.000 GMT.
As I mentioned, if you're not currently in GMT, then you have to set the TZ of the DateFormat to GMT. Right now, it's showing you the time in your TZ. If you included the date in your SimpleDateFormat, you'd see either 1/1/1970 or 12/31/1969, depending on which TZ you're in.
Bottom line: You're trying to use these classes in a way they're not meant for, and while you can get the results you want for a limited set of inputs if you understand what these classes do and how to work with that, it's a brittle approach and comes with all kinds of caveats.

New to java needs advice

Hi,
I'm completely new to java and after a few days search found Studio Creator and decided to use it. Happily developing for a week in JSC, I reached the deployment to Tomcat stage.
Mybe I'm missing something but I find this stage ruining the ease-of-use feeling which I got when I started using JSC.
Am I right that JSC doesn't have a built-in functionality to deploy to Tomcat whithout my intervention, considering my total unfamiliarity with xml, jsp, mysql, etc.?
If so do you guys know of another easy-to-use IDE like JSC?
Any pointers are greatly appreciated.
Thanks, Abraham

Hi,
Try this FAQ on
How do I deploy web applications developed with Java Studio Creator to the Tomcat Servlet/JSP Container?
at http://developers.sun.com/prodtech/javatools/jscreator/reference/faqs/technical.jsp
MJ

I am totally new in Java.

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