Need help with java thread program
Hi
I have an applet which does some painting etc, i need to write a thread which runs in background, and if there is no user activity for 30 min will refresh the screen.
I have one good thing that all user options go from one program so i know when user does some thing.
How do i write this thread program?
1. I need this program to start counter as soon as some activity is done by user
2. When user does some thing stop this thread
3. when user completes his action restart the thread with 30 min timer.
4. when there is no activity for 30 min refresh the screen
Any help will be really good
Ashish
Not sure what the problem is. Your pseudo code looks good to me.
The only suggestion I would make is that your use a Timer so you don't have to worry about creating your own Thread. You schedule a Timer to fire in 30 minutes. Everytime you have activiity you cancel the timer and reschedule it.
Similar Messages
-
Need help with my addressbook program
hi,
i need help with my program here. this one should works as:
- saves user input into a txt file
- displays name of the saved person on the jlist whenever i run the program
- displays info about the person when clicked via textboxes given by reading the txt file where the user inputs are
- should scroll when the list exceeds the listbox
import java.awt.event.*;
import java.awt.*;
import javax.swing.*;
import javax.swing.JList;
import java.awt.event.ActionListener;
import java.io.*;
import javax.swing.event.*;
import java.io.FilterInputStream;
public class AddressList extends JPanel implements ActionListener
JTextField txt1 = new JTextField();
JTextField txt2 = new JTextField();
JTextField txt3 = new JTextField();
DefaultListModel mdl = new DefaultListModel();
JList list = new JList();
JScrollPane listScroller = new JScrollPane(list);
ListSelectionModel listSelectionModel;
File fob = new File("Address3.txt");
String name;
char[] chars;
public void ListDisplay()
try
RandomAccessFile rand = new RandomAccessFile(fob,"rw");
BufferedReader br = new BufferedReader(new FileReader("Address3.txt"));
if(fob.exists())
while((name = rand.readLine()) != null)
chars = name.toCharArray();
if(chars[0] == '*')
mdl.addElement(name);
list.setModel(mdl);
if(chars[0] == '#')
continue;
else
System.out.println("No such file..");
catch(IOException a)
System.out.println(a.getMessage());
public AddressList()
this.setLayout(null);
listSelectionModel = list.getSelectionModel();
listSelectionModel.addListSelectionListener(new ListInfo());
list.setBounds(10,40,330,270);
listScroller.setBounds(320,40,20,100);
add(list);
add(listScroller);
JLabel lbl4 = new JLabel("Name: ");
lbl4.setBounds(400,10,80,30);
add(lbl4);
JLabel lbl5 = new JLabel("Cellphone #: ");
lbl5.setBounds(400,50,80,30);
add(lbl5);
JLabel lbl6 = new JLabel("Address: ");
lbl6.setBounds(400,90,80,30);
add(lbl6);
JLabel lbl7 = new JLabel("List ");
lbl7.setBounds(10,10,100,30);
add(lbl7);
txt1.setBounds(480,10,200,30);
add(txt1);
txt2.setBounds(480,50,200,30);
add(txt2);
txt3.setBounds(480,90,200,30);
add(txt3);
JButton btn1 = new JButton("Add");
btn1.setBounds(480,130,100,30);
btn1.addActionListener(this);
btn1.setActionCommand("Add");
add(btn1);
JButton btn2 = new JButton("Save");
btn2.setBounds(480,170,100,30);
btn2.addActionListener(this);
btn2.setActionCommand("Save");
add(btn2);
JButton btn3 = new JButton("Cancel");
btn3.setBounds(480,210,100,30);
btn3.addActionListener(this);
btn3.setActionCommand("Cancel");
add(btn3);
JButton btn4 = new JButton("Close");
btn4.setBounds(480,250,100,30);
btn4.addActionListener(this);
btn4.setActionCommand("Close");
add(btn4);
public static void main(String[]args)
JFrame frm = new JFrame("Address List");
AddressList panel = new AddressList();
frm.getContentPane().add(panel,"Center");
frm.setSize(700,350);
frm.setVisible(true);
panel.ListDisplay();
public void actionPerformed(ActionEvent e)
String cmd;
cmd = e.getActionCommand();
if(cmd.equals("Add"))
txt1.setText("");
txt2.setText("");
txt3.setText("");
else if(cmd.equals("Save"))
mdl.addElement(txt1.getText());
list.setModel(mdl);
try
RandomAccessFile rand = new RandomAccessFile(fob,"rw");
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
LineNumberReader line = new LineNumberReader(br);
if(fob.exists())
rand.seek(fob.length());
rand.writeBytes("* " + txt1.getText());
rand.writeBytes("\r\n" + "# " + txt2.getText());
rand.writeBytes("\r\n" + "# " + txt3.getText() + "\r\n");
else
System.out.println("No such file..");
txt1.setText("");
txt2.setText("");
txt3.setText("");
catch(IOException a)
System.out.println(a.getMessage());
else if(cmd.equals("Cancel"))
txt1.setText("");
txt2.setText("");
txt3.setText("");
else if(cmd.equals("Close"))
System.exit(0);
class ListInfo implements ListSelectionListener
public void valueChanged(ListSelectionEvent e)
ListSelectionModel lsm = (ListSelectionModel)e.getSource();
int minIndex = lsm.getMinSelectionIndex();
int maxIndex = lsm.getMaxSelectionIndex();
try //*this one should display the info of the person whenever i click the person's name at the list box via textbox.. but i cant seem to get it right since it always display the info of the first person inputed.. i tried to get the program to display them whenever it reads lines with * on them....
File fob = new File("Address3.txt");
RandomAccessFile rand = new RandomAccessFile(fob,"rw");
BufferedReader br = new BufferedReader(new FileReader("Address3.txt"));
LineNumberReader line = new LineNumberReader(br);
if(fob.exists())
for(int i = minIndex; i<=maxIndex; i++)
if(lsm.isSelectedIndex(i))
while((name = rand.readLine()) != null)
chars = name.toCharArray();
if(chars[0] == '#')
continue;
if(chars[0] == '*')
txt1.setText(rand.readLine());
txt2.setText(rand.readLine());
txt3.setText(rand.readLine());
else
System.out.println("No such file..");
catch(IOException a)
System.out.println(a.getMessage());
}the only problem now is about how it should display the right info about the person whenever i click its name on the list.. something about file reading or something, i just cant figure it out.
and also about how to make it scroll once it exceeds the list.. i cant make it work, maybe something about wrong declaration..
thanks in advance..
Edited by: syder on Mar 14, 2008 2:26 AMLike said before, do one thing at a time. At startup, something like:
//put all the content in a list
ArrayList<String> lines = new ArrayList<String>();
while(String line=rand.readLine()!=null) {
lines.add(line);
}If you follow the good advice to create a class to encapsulate the entries, you could populate a list of such entries like this:
static final int ENTRY_SIZE = 3;//you have 3 fields now, better to have a constant if that changes
ArrayList<Entry> entries = new ArrayList<Entry>();
for(int i=0; i<lines.size(); i+=ENTRY_SIZE) {
Entry entry = new Entry(lines.get(i), lines.get(i+1), lines.get(i+2);
entries.add(newEntry);
}You could also do both of the above in one run, but I think you will understand better what's happening if you do one thing at a time.
If you don't want to put the entries in an encapsulating class, you can still access this without looping:
int listStartIdx = <desired_entry_index>*ENTRY_SIZE;
String att1 = lines.get(listStartIdx).substring(1);
String att2 = lines.get(listStartIdx+1).substring(1);
String att3 = lines.get(listStartIdx+2).substring(1); -
Need help with a rudimentary program
I'm sort of new at this so i need help with a few things... I'm making a program to compile wages and i need answers with three things: a.) what are the error messages im getting meaning? b.) How can i calculate the state tax as 2% of my gross pay with the first $200 excluded and c.) how can i calculate the local tax as a flat $10 with $2 deducted for each dependant. any help is appreciated
Here is what i have so far:
public class WagesAsign1
public static void main(String[] args)
int depend=4;
double hrsWork=40;
double payRate=15;
double grossPay;
grossPay=payRate*hrsWork;
double statePaid;
double stateTax=2.0;
statePaid=grossPay*(stateTax/100);
double localPaid;
double localTax=10.0;
localPaid=grossPay*(localTax/100);
double fedPaid;
double fedTax=10.0;
double taxIncome;
fedPaid=taxIncome*(fedTax/100);
taxIncome=grossPay-(statePaid+localPaid);
double takeHome;
System.out.println("Assignment 1 Matt Foraker\n");
System.out.println("Hours worked="+hrsWork+" Pay rate $"+payRate+" per/hour dependants: "+depend);
System.out.println("Gross Pay $"+grossPay+"\nState tax paid $"+statePaid+"\nLocal tax paid $"+localPaid+"\nFederal tax paid $"+fedPaid);
System.out.println("You take home a total of $"+takeHome);
and these are the error messages so far:
WagesAsign1.java:23: variable taxIncome might not have been initialized
fedPaid=taxIncome*(fedTax/100);
^
WagesAsign1.java:29: variable takeHome might not have been initialized
System.out.println("You take home a total of $"+takeHome);
^edit: figured it out... please delete post
Message was edited by:
afroryan58 -
Hi, I'm not sure if I'm allowed to post questions on this forum but I can't find anywhere to talk to helpful people about programming.
I'm making a dnd interface for JComponents. So far I've made a simple program that has a Component that can be lifted from a container and braught to the glass pane then later moved to anywhere on the screen and dropped into the container below it. Here's where my problems come:
1) Rite now my 'Movable Component' is a JPanel which is just colored in. I want to either take a Graphic2d from a JComponent/Component and draw it on the JPanel or change the JPanel to the component I want to paint and disable the component.
The problem with getting the Graphics2d is that if the component isn't on the screen it doesn't make a graphic object. I tried messing with the ui delicate and overriding parental methods for paintComponent, repaint, and that repaintChildren(forget name) but I haven't had luck getting a good graphics object. I was thinking of, at the beginning of running the program, putting 1 of each component onto the screen for a second then removing it but I'd rather not. I'd also like to change the graphics dynamicly if someone stretches the component there dropping and what not.
The problem with disabling is that it changes some of the visual features of Components. I want to be able to update the Component myself to change how it looks and I don't want disabling to gray out components.
I mainly just dont want the components to do any of there normal fuctions. This is for a page builder, by the way.
Another problem I'm having is that mouseMotionListener is allowing me to select 2 components that are on top of one another when there edges are near each other. I don't know if theres a fix to this other than changing the Java Class.
My next problem is a drop layout manager, but I'm doing pretty good with that rite now. It'll problem just move components out of the way of the falling component.
One last thing I need help with is that I don't want the object that's being carried to go across the menu bar and certain areas. When I'm having the object being carried I have it braught up to the glass pane which allows it to move anywhere. Does anyone have any idea how I could prevent the component from being over the menu bars and other objects? I might have to make 1 panel is the movable area that can then be broken down into the 'component bank', 'building page' and whatever else I'm gonna need.
This is all just test code to get together for when I make the real program but I need to make sure it'll be possible without a lot of hacking of code.
Sorry for the length. Thanks for any help you can give.The trick to making viewable components that have no behaviour, is to render them onto an image of some sort (eg a BufferedImage). You can then display the Image on a JLabel that can be dragged around the desktop.
Here is a piece of code that does the component rendering for you. This particular example uses a fixed component size, but you can modify that as you choose of course...public class JComponentImage
private static GraphicsConfiguration gConfig;
private static Dimension compSize = new Dimension(80, 22);
private static Image image = null;
public static Image getImage(Class objectClass)
if (gConfig == null)
GraphicsEnvironment gEnv = GraphicsEnvironment.getLocalGraphicsEnvironment();
GraphicsDevice gDevice = gEnv.getDefaultScreenDevice();
gConfig = gDevice.getDefaultConfiguration();
image = gConfig.createCompatibleImage(compSize.width, compSize.height);
JComponent jc = (JComponent) ObjectFactory.instantiate(objectClass);
jc.setSize(compSize);
Graphics g = image.getGraphics();
g.setColor(Color.LIGHT_GRAY);
g.fillRect(0, 0, compSize.width, compSize.height);
g.setColor(Color.BLACK);
jc.paint(g);
return image;
}And here is the class that makes the dragable JLabel using the class above...public class Dragable extends JLabel
private static DragSource dragSource = DragSource.getDefaultDragSource();
private static DragGestureListener dgl = new DragMoveGestureListener();
private static TransferHandler th = new ObjectTransferHandler();
private Class compClass;
private Image image;
Dragable(Class compClass)
this.compClass = compClass;
image = JComponentImage.getImage(compClass);
setIcon(new ImageIcon(image));
setTransferHandler(th);
dragSource.createDefaultDragGestureRecognizer(this,
DnDConstants.ACTION_COPY,
dgl);
public Class getCompClass()
return compClass;
}Oh and here is ObjectFactory which simply instantiates Objects of a given class and sets their text to their classname (very crudely)...public class ObjectFactory
public static Object instantiate(Class objectClass)
Object o = null;
try
o = objectClass.newInstance();
catch (Exception e)
System.out.println("ObjectFactory#instantiate: " + e);
String name = objectClass.getName();
int lastDot = name.lastIndexOf('.');
name = name.substring(lastDot + 1);
if (o instanceof JLabel)
((JLabel)o).setText(name);
if (o instanceof JButton)
((JButton)o).setText(name);
if (o instanceof JTextComponent)
((JTextComponent)o).setText(name);
return o;
}Two more classes required by this codepublic class ObjectTransferHandler extends TransferHandler {
private static DataFlavor df;
* Constructor for ObjectTransferHandler.
public ObjectTransferHandler() {
super();
try {
df = new DataFlavor(DataFlavor.javaJVMLocalObjectMimeType);
} catch (ClassNotFoundException e) {
Debug.trace(e.toString());
public Transferable createTransferable(JComponent jC) {
Transferable t = null;
try {
t = new ObjectTransferable(((Dragable) jC).getCompClass());
} catch (Exception e) {
Debug.trace(e.toString());
return t;
public int getSourceActions(JComponent c) {
return DnDConstants.ACTION_MOVE;
public boolean canImport(JComponent comp, DataFlavor[] flavors) {
if (!(comp instanceof Dragable) && flavors[0].equals(df))
return true;
return false;
public boolean importData(JComponent comp, Transferable t) {
JComponent c = null;
try {
c = (JComponent) t.getTransferData(df);
} catch (Exception e) {
Debug.trace(e.toString());
comp.add(c);
comp.validate();
return true;
public class ObjectTransferable implements Transferable {
private static DataFlavor df = null;
private Class objectClass;
ObjectTransferable(Class objectClass) {
try {
df = new DataFlavor(DataFlavor.javaJVMLocalObjectMimeType);
} catch (ClassNotFoundException e) {
System.out.println("ObjectTransferable: " + e);
this.objectClass = objectClass;
* @see java.awt.datatransfer.Transferable#getTransferDataFlavors()
public DataFlavor[] getTransferDataFlavors() {
return new DataFlavor[] { df };
* @see java.awt.datatransfer.Transferable#isDataFlavorSupported(DataFlavor)
public boolean isDataFlavorSupported(DataFlavor testDF) {
return testDF.equals(df);
* @see java.awt.datatransfer.Transferable#getTransferData(DataFlavor)
public Object getTransferData(DataFlavor arg0)
throws UnsupportedFlavorException, IOException {
return ObjectFactory.instantiate(objectClass);
}And of course the test class:public class DragAndDropTest extends JFrame
JPanel leftPanel = new JPanel();
JPanel rightPanel = new JPanel();
Container contentPane = getContentPane();
Dragable dragableJLabel;
Dragable dragableJButton;
Dragable dragableJTextField;
Dragable dragableJTextArea;
* Constructor DragAndDropTest.
* @param title
public DragAndDropTest(String title)
super(title);
dragableJLabel = new Dragable(JLabel.class);
dragableJButton = new Dragable(JButton.class);
dragableJTextField = new Dragable(JTextField.class);
dragableJTextArea = new Dragable(JTextArea.class);
leftPanel.setBorder(new EtchedBorder());
BoxLayout boxLay = new BoxLayout(leftPanel, BoxLayout.Y_AXIS);
leftPanel.setLayout(boxLay);
leftPanel.add(dragableJLabel);
leftPanel.add(dragableJButton);
leftPanel.add(dragableJTextField);
leftPanel.add(dragableJTextArea);
rightPanel.setPreferredSize(new Dimension(500,500));
rightPanel.setBorder(new EtchedBorder());
rightPanel.setTransferHandler(new ObjectTransferHandler());
contentPane.setLayout(new BorderLayout());
contentPane.add(leftPanel, "West");
contentPane.add(rightPanel, "Center");
public static void main(String[] args)
JFrame frame = new DragAndDropTest("Drag and Drop Test");
frame.pack();
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
frame.setVisible(true);
}I wrote this code some time ago, so it won't be perfect but hopefully will give you some good ideas.
Regards,
Tim -
Need help with a simple program (should be simple anyway)
I'm (starting to begin) writing a nice simple program that should be easy however I'm stuck on how to make the "New" button in the file menu clear all the fields. Any help? I'll attach the code below.
====================================================
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class Message extends JFrame implements ActionListener {
public void actionPerformed(ActionEvent evt) {
text1.setText(" ");
text2.setText("RE: ");
text3.setText(" ");
public Message() {
super("Write a Message - by Kieran Hannigan");
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setSize(370,270);
FlowLayout flo = new FlowLayout(FlowLayout.RIGHT);
setLayout(flo);
//Make the bar
JMenuBar bar = new JMenuBar();
//Make "File" on Menu
JMenu File = new JMenu("File");
JMenuItem f1 = new JMenuItem("New");f1.addActionListener(this);
JMenuItem f2 = new JMenuItem("Open");
JMenuItem f3 = new JMenuItem("Save");
JMenuItem f4 = new JMenuItem("Save As");
JMenuItem f5 = new JMenuItem("Exit");
File.add(f1);
File.add(f2);
File.add(f3);
File.add(f4);
File.add(f5);
bar.add(File);
//Make "Edit" on menu
JMenu Edit = new JMenu("Edit");
JMenuItem e1 = new JMenuItem("Cut");
JMenuItem e2 = new JMenuItem("Paste");
JMenuItem e3 = new JMenuItem("Copy");
JMenuItem e4 = new JMenuItem("Repeat");
JMenuItem e5 = new JMenuItem("Undo");
Edit.add(e5);
Edit.add(e4);
Edit.add(e1);
Edit.add(e3);
Edit.add(e2);
bar.add(Edit);
//Make "View" on menu
JMenu View = new JMenu("View");
JMenuItem v1 = new JMenuItem("Bold");
JMenuItem v2 = new JMenuItem("Italic");
JMenuItem v3 = new JMenuItem("Normal");
JMenuItem v4 = new JMenuItem("Bold-Italic");
View.add(v1);
View.add(v2);
View.add(v3);
View.addSeparator();
View.add(v4);
bar.add(View);
//Make "Help" on menu
JMenu Help = new JMenu("Help");
JMenuItem h1 = new JMenuItem("Help Online");
JMenuItem h2 = new JMenuItem("E-mail Programmer");
Help.add(h1);
Help.add(h2);
bar.add(Help);
setJMenuBar(bar);
//Make Contents of window.
//Make "Subject" text field
JPanel row2 = new JPanel();
JLabel sublabel = new JLabel("Subject:");
row2.add(sublabel);
JTextField text2 = new JTextField("RE:",24);
row2.add(text2);
//Make "To" text field
JPanel row1 = new JPanel();
JLabel tolabel = new JLabel("To:");
row1.add(tolabel);
JTextField text1 = new JTextField(24);
row1.add(text1);
//Make "Message" text area
JPanel row3 = new JPanel();
JLabel Meslabel = new JLabel("Message:");
row3.add(Meslabel);
JTextArea text3 = new JTextArea(6,22);
messagearea.setLineWrap(true);
messagearea.setWrapStyleWord(true);
JScrollPane scroll = new JScrollPane(text3,
JScrollPane.VERTICAL_SCROLLBAR_ALWAYS,
JScrollPane.HORIZONTAL_SCROLLBAR_NEVER);
//SpaceLine
JPanel spaceline = new JPanel();
JLabel spacer = new JLabel(" ");
spaceline.add(spacer);
row3.add(scroll);
add(row1);
add(row2);
add(spaceline);
add(spaceline);
add(row3);
setVisible(true);
public static void main(String[] arguments) {
Message Message = new Message();
}persiandude wrote:
Topic: Need help with if, else, and which statements and loops.
How would I display 60 < temp. <= 85 in java
System.out.println("60 < temp. <= 85 in java");
another question is how do I ask a question like want to try again (y/n) after a output and asking that everytime I type in yes after a output and terminate when saying No.Sun's [basic Java tutorial|http://java.sun.com/docs/books/tutorial/]
Sun's [New To Java Center|http://java.sun.com/learning/new2java/index.html].Includes an overview of what Java is, instructions for setting up Java, an intro to programming (that includes links to the above tutorial or to parts of it), quizzes, a list of resources, and info on certification and courses.
[http://javaalmanac.com|http://javaalmanac.com]. A couple dozen code examples that supplement [The Java Developers Almanac|http://www.amazon.com/exec/obidos/tg/detail/-/0201752808?v=glance].
jGuru. A general Java resource site. Includes FAQs, forums, courses, more.
JavaRanch. To quote the tagline on their homepage: "a friendly place for Java greenhorns." FAQs, forums (moderated, I believe), sample code, all kinds of goodies for newbies. From what I've heard, they live up to the "friendly" claim.
Bruce Eckel's [Thinking in Java|http://mindview.net/Books/DownloadSites] (Available online.)
Joshua Bloch's [Effective Java|http://www.amazon.com/Effective-Java-2nd-Joshua-Bloch/dp/0321356683/ref=pd_bbs_1?ie=UTF8&s=books&qid=1214349768&sr=8-1]
Bert Bates and Kathy Sierra's [Head First Java|http://www.amazon.com/exec/obidos/tg/detail/-/0596004656?v=glance].
James Gosling's [The Java Programming Language|http://www.bookpool.com/sm/0321349806]. -
Need help with accessing the program.
I need help with accessing my adobe creative cloud on my windows 8.1 laptop. I have an account but do not have an app. I need this for my online classes. Please help!
Link for Download & Install & Setup & Activation may help
-Chat http://www.adobe.com/support/download-install/supportinfo/ -
Need help with Java programming installation question
Sorry for my lack of knowledge about Java programming, but:....
A while back I thought I had updated my Java Runtime Environment programming. But I now apparently have two programs installed, perhaps through my not handling the installation properly. Those are:
J2SE Runtime Environment 5.0 update 5.0 (a 118MB file)
and:
Java 2 Runtime Environment, SE v 1.4.2_05 (a 108MB file)
Do I need both of these installed? If not, which should I uninstall?
Or, should I just leave it alone, and not worry about it?
Yeah, I don't have much in the way of technical knowledge...
Any help or advice would be appreciated. Thank you.
Bob VanHorstThanks for the feedback. I think I'll do just that. Once in a while I have a problem with Java not bringing up a webcam shot, but when that happens, it seems to be more website based than a general condition.
-
ok so i have a midterm and need help this question that is gonna be on the midterm. i dont know how to do it and its worth 16 marks!!!! here it is
the UW Orchestra wants to produce a CD containing all the pieces of music
from its upcoming concert. In order to do that, it needs to calculate the total length of time for the
CD. In addition, the conductor wishes to know which piece of music has the longest duration.
Sample output for the program.
The Swan (3.88)
The Bee (0.98)
Claire de Lune (6.02)
Liebesfreund (3.38)
Ragtime (3.48)
The total time for the CD is 18.74 minutes.
The longest piece is Claire de Lune.
Do not include the HTML that is required to embed the program into a Web page (that is, show
only what you would write between <script> and </script> tags).
[4 marks] In the following space, define a function, Print, that takes two parameters, Title and
Length, and outputs a line of text such that Title appears in italics, followed by Length in
parentheses. The function also returns the value of Length.
For example, Print("My World",30) will output the line
My World (30)
and return the value 30.
Put your JavaScript program for the remainder of this question in the space provided on the next
two pages.
[9 marks]. For each piece of music, your program should input the title of the piece and the
duration (in minutes) for that piece, and it should output a line showing those values using the
Print function just defined. After all pieces have been listed, the program should output the
total length of time for the CD, adding in 0.25 minutes between each piece of music (which is
needed on the CD to separate the pieces).
[3 marks] The program should also output the name of the piece that has the longest playing
time.
Use reasonable variable names, indentation and good programming style. Documentation and
comments are not required, but you may add them to explain any assumptions you might want to
make. You need not check that the input is valid, and you may assume that no two pieces have the
same duration.
can anyone help me out! i would be indebt of ur kindness if u can help me out!This forum is for Java, not JavaScript. The two have nothing to do with each other.
And anyway, this is your studying, so you should try to do it, put forth your best effort, and ask specific questions (on the proper fourm). -
Need Help with simple array program!
Hi, I have just recently started how to use arrays[] in Java and I'm a bit confused and need help designing a program.
What this program does, it reads in a range of letters specified by the user. The user then enters the letters (a, b or c) and stores these characters into an array, which the array's length is equal to the input range the user would enter at the start of the program. The program is then meant to find how many times (a,b and c) appears in the array and the Index it first appears at, then prints these results.
Here is my Code for the program, hopefully this would make sense of what my program is suppose to do.
import B102.*;
class Letters
static int GetSize()
int size = 0;
boolean err = true;
while(err == true)
Screen.out.println("How Many Letters would you like to read in?");
size = Keybd.in.readInt();
err = Keybd.in.fail();
Keybd.in.clearError();
if(size <= 0)
err = true;
Screen.out.println("Invalid Input");
return(size);
static char[] ReadInput(int size)
char input;
char[] letter = new char[size];
for(int start = 1; start <= size; start++)
System.out.println("Please enter a letter (a, b or c) ("+size+" max), enter # to stop:");
input = Keybd.in.readChar();
while((input != 'a') && (input != 'b') && (input != 'c') && (input != '#'))
Screen.out.println("Invalid Input");
System.out.println("Please enter a letter (a, b or c) ("+size+" max, enter # to stop:");
input = Keybd.in.readChar();
while(input == '#')
start == size;
break;
for(int i = 0; i < letter.length; i++)
letter[i] = input;
return(letter);
static int CountA(char[] letter)
int acount = 0;
for(int i = 0; i < letter.length; i++)
if(letter[i] == 'a')
acount++;
return(acount);
static int CountB(char[] letter)
int bcount = 0;
for(int i = 0; i < letter.length; i++)
if(letter[i] == 'b')
bcount++;
return(bcount);
static int CountC(char[] letter)
int ccount = 0;
for(int i = 0; i < letter.length; i++)
if(letter[i] == 'c')
ccount++;
return(ccount);
static int SearchA(char[] letter)
int ia;
for(ia = 0; ia < letter.length; ia++)
if(letter[ia] == 'a')
return(ia);
return(ia);
static int SearchB(char[] letter)
int ib;
for(ib = 0; ib < letter.length; ib++)
if(letter[ib] == 'b')
return(ib);
return(ib);
static int SearchC(char[] letter)
int ic;
for(ic = 0; ic < letter.length; ic++)
if(letter[ic] == 'c')
return(ic);
return(ic);
static void PrintResult(char[] letter, int acount, int bcount, int ccount, int ia, int ib, int ic)
if(ia <= 1)
System.out.println("There are "+acount+" a's found, first appearing at index "+ia);
else
System.out.println("There are no a's found");
if(ib <= 1)
System.out.println("There are "+bcount+" b's found, first appearing at index "+ib);
else
System.out.println("There are no b's found");
if(ic <= 1)
System.out.println("There are "+ccount+" c's found, first appearing at index "+ic);
else
System.out.println("There are no c's found");
return;
public static void main(String args[])
int size;
char[] letter;
int acount;
int bcount;
int ccount;
int ia;
int ib;
int ic;
size = GetSize();
letter = ReadInput(size);
acount = CountA(letter);
bcount = CountB(letter);
ccount = CountC(letter);
ia = SearchA(letter);
ib = SearchB(letter);
ic = SearchC(letter);
PrintResult(letter, acount, bcount, ccount, ia, ib, ic);
return;
} Some errors i get with my program are:
When reading in the letters to store into the array, I get the last letter I entered placed into the entire array. Also I believe my code to find the Index is incorrect.
Example Testing: How many letters would you like to read? 3
Enter letter (a, b or c) (# to quit): a
Enter letter (a, b or c) (# to quit): b
Enter letter (a, b or c) (# to quit): c
It prints "There are no a's'" (there should be 1 a at index 0)
"There are no b's" (there should be 1 b at index 1)
and "There are 3 c's, first appearing at index 0" ( there should be 1 c at index 2)
The last thing is that my code for when the user enters "#" that the input of letters would stop and the program would then continue over to the counting and searching part for the letters, my I believe is correct but I get the same problem as stated above where the program takes the character "#" and stores it into the entire array.
Example Testing:How many letters would you like to read? 3
Enter letter (a, b or c) (# to quit): a
Enter letter (a, b or c) (# to quit): #
It prints "There are no a's'" (should have been 1 a at index 0)
"There are no b's"
and "There are no c's"
Can someone please help me??? or does anyone have a program simular to this they have done and would'nt mind showing me how it works?
Thanks
lou87.Without thinking too much...something like this
for(int start = 0; start < size; start++) {
System.out.println("Please enter a letter (a, b or c) ("+size+" max), enter # to stop:");
input = Keybd.in.readChar();
while((input != 'a') && (input != 'b') && (input != 'c') && (input != '#')) {
Screen.out.println("Invalid Input");
System.out.println("Please enter a letter (a, b or c) ("+size+" max, enter # to stop:");
input = Keybd.in.readChar();
if(input == '#') {
break;
letter[start] = input;
}you dont even need to do start = size; coz with the break you go out of the for loop. -
Need help with java will even pay
I need extreme help. I just don't have time lately to write these programs and I have fallen extremely behind. Basically all I need is to pass this class and right now until I can get some more help I just can't make the deadlines. If someone could help me I will pay you just like a tutor.
Requirements for Lab.
You will need to develop a variety of classes for this lab. Specifically, you need to create:
+1. a "PersonGUI" class that displays fields for a person's: firstName, lastName, identificationNum, and sex.+
+2. a "StudentGUI" class that provides Java components for the entry of: classification (freshman, sophomore, junior, senior, or graduate student), and Checkboxes for (a student being in the Honor's program and/or in the ROTC).+
+3. a "FacultyGUI" class that provides Java components for the entry of: rank (instructor, assistant, associate, or full professor), years of service, and salary.+
+4. a "Statistics" class that, when instantiated, creates an object containing an instance variable for each of the the statistical values outlined below. (Each of these instance variables should be declared to be "private".)+
Your main Lab6 class should provide a means for the user to:
+1. Specify the kind of personal data to be entered (Student or Faculty), and+
+2. Then, depending on the choice made, appropriate fields should be displayed to allow the user to input appropriate information for the type of personal data being entered, and+
+3. Controls that support the following functionality:+
* a "CANCEL" control that will terminate any operation currently being performed and return the user to the "Startup" window.
* a "SAVE" control that will cause the just entered data to be harvested from the graphical user interface and the appropriate statistics to be updated. Note: this function may NOT be performed if any of the student or faculty member data fields have not been filled in.
* a "RESET" control that will erase all information recorded to date (i.e., all summary variables are reset to zero).
* a "CLEAR" control that will erase all fields for the personal data currently being entered.
* and a "DISPLAY TOTALS" control that will display, when pressed, the following data:
+1. For students:+
+1. total number of students entered so far,+
+2. number who are male and number who are female,+
+3. number of freshmen, sophomores, juniors, seniors, and graduate students,+
+4. number of students who are in the Honor's program and number who are in the ROTC.+
+2. For faculty:+
+1. total number of faculty entered so far,+
+2. number who are male and number who are female,+
+3. the name and salary of the highest paid faculty member on campus.+
Your program should validate numeric data to the extent:
+1. no numeric field (id number, years of service, or salary) may be left blank by the user. If done so, the user should be alerted to enter a numeric value.+
+2. when the user enters a "years of service" value for a faculty member - the value entered should be verified to be a valid integer value in the range 1 to 50. If the data entered is outside the valid range or is not a valid integer - your program should reject the value and prompt the user that invalid data has been entered and that a new value is necessary.+
+3. when a faculty salary is entered, verify that it is a floating-point value in the range $35,000 to $200,000. Handle invalid data as described above.+
+4. Similarly, if an invalid integer value is entered for the identification number, the value should be rejected and the user prompted to reenter.+
+5. Information should not be saved, nor should statistical values be updated, until all numeric data has been validated.+
Note -- You will be graded on appropriate use of instance vs. local variables, use of methods, and passing parameters and returning appropriate values.
+1. The 'Statistics" class MUST provide "mutator" and "accessor" methods that are required to access values or to modify the values of any variable. REMEMBER ALL VARIABLES ARE DECLARED TO BE "private"!!+
+2. You should implement methods to verify the data, as detailed above. The methods should return boolean values indicating whether the data is acceptable or not.+Sorry to hear about your problems - lack of time, having fallen behind, imminent failure etc - but none of these are Java problems.
This site deals with Java problems: compiler or runtime behaviour that people can't understand. If you have problems of that sort (and especially if solving those problems would help with the problems you did describe) then post them.
Otherwise you would seem to be in the wrong place. -
Need help with java J2Se 5.0 upgrade 2
Having problems with Java when playing on Pogo, the Vaults of Atlantis. When loading, I am getting a message that says that I need to remove and download again, java. That it is not working correctly. I did that yesterday, 05/27/05 and am still experiencing the problem but only after signing off from Pogo and AOL and then trying to sign back on again later in the day. I have to shutdown my computer and bring it back up again and then I can load the Vaults of Atlantis. I have noticed that when I do sign-off from Pogo and AOL, that my java cup stays on in my deskbar. Is that supposed to be normal or is it supposed to disappear? If it is supposed to disappear, what can I do to fix that problem?
Please, can anyone help?Go here http://www.java.com/en/ and click "Download Now".
If that has problems, click the "Manual Download" link and download the "Windows (Offline Installation)".
If there are problems, review the Help information to resolve. -
Need help with spell checker program
Hi
I am writing a spell checker program and need help for a simple logic.I have "List" of correctly spelled words and a String array of wrong spelled words.How can I compare both and tell that for eg xyz word is not spelled correctly.BigDaddyLoveHandles wrote:
To learn more about Map, take the collection tutorial: [http://java.sun.com/docs/books/tutorial/collections/index.html]
(Actually, to me it sounds like you have a Set of correctly spelled words and another Set of words which may or may not be correctly spelled, and you want the difference...)That is what it sounds like to me also, and that is easy.
JSG -
Help with Java Inventory Program - I almost got it
Hello, I'm new to the forum so please don't hang me if I'm not posting this correctly or in the right place. I'm writing a Java Inventory Program for class and everything was great until we had to modify it to sort by product name (in my case dvd's). The problem is my arrays for inventory count and price are thrown off when I sort by dvd name because they are predefined. I could cheat and just rearrange the array in a logical order according to the dvd title but that isn't really the answer for me. Can someone help me do where my inventory count and price don't go out of wack when I sort by dvd name, I really don't want to start over.
Here is my code:
// Java InventoryProgram2
// Purpose of application is to Display DVD Inventory
import java.util.Arrays;
public class InventoryProgram2 // declare public class
{ // Start of public class InventoryProgram1
String dvdName[] = { "The Departed", "The Dark Knight","The Mummy", "Minority Report"};
double itemNum;
float stockCount[] = {3, 5, 8,2};
float totalValue [] = new float [4];
float price[] = { 19, 22, 17, 14};
float totInvVal;
// Method for printing dvdName the dvdName
public void DvdName ()
{ // Start of print method
// For loop to calculate total value
Arrays.sort(dvdName);
for( int itemNum = 0; itemNum < dvdName.length; itemNum ++ )
totalValue[itemNum] = stockCount[itemNum] * price[itemNum];
System.out.printf( "%s %15s %12s %12s %12s\n", "Item Number", "Dvd Name", "Price", "Stock", "Total"); // Prints title of column
for ( int itemNum = 0; itemNum <dvdName.length; itemNum ++ )
System.out.printf("%-8d %20s %10.02f %12.02f %12.02f\n", itemNum, dvdName[itemNum], price [itemNum],stockCount[itemNum], totalValue[itemNum]); // Calls the value of each column
} // end of method to print dvdName
// Method for total value of the inventory
public void totalInvValue()
{ //start of method to calc total inv value
totInvVal = stockCount [0] * price [0] + stockCount [1] * price [1] + stockCount [2] * price [2] + stockCount [3] * price [3];
System.out.printf("%s", "The Total Value of the Inventory is:","%10.02f");
System.out.printf("$%.02f", totInvVal);
} // end of method to calc total inv value
} // End of public class InventoryProgram1
// Java InventoryProgram2_Test
// Purpose of application is to Display DVD Inventory
public class InventoryProgram2_Test
{ // Start Bracket for InventoryProgram1
public static void main ( String args[] )
{ // Start Bracket for Public Main
InventoryProgram2 myInventoryProgram2 = new InventoryProgram2(); // invokes InventoryProgram1
myInventoryProgram2.DvdName (); // calls DvdName Method
myInventoryProgram2.totalInvValue(); // call method total inventory value
} // End Bracket for Public Main
} // End Bracket for InventoryProgram1
Edited by: ozzie2132 on Aug 11, 2008 6:57 PM
Edited by: ozzie2132 on Aug 11, 2008 6:57 PMa_turingmachine wrote:
naive ex:
class DVD {
String dvdName;
float stockCount;
float price;
}--turing machine:
Suggestion 1: If you are going to give code for someone doing homework, try not to give exactly what the OP needs but rather something similar. They will learn a lot more if they have to process your recommendations and then create their own code.
Suggestion 2: When posting your code, please use code tags so that your code will retain its formatting and be readable. To do this, you will need to paste already formatted code into the forum, highlight this code, and then press the "code" button at the top of the forum Message editor prior to posting the message. You may want to click on the Preview tab to make sure that your code is formatted correctly. Another way is to place the tag [code] at the top of your block of code and the tag [/code] at the bottom, like so:
[code]
// your code block goes here.
// note the differences between the tag at the top vs the bottom.
[/code]or
{code}
// your code block goes here.
// note here that the tags are the same.
{code} -
Need help with Java always get error
hey guys need help
this the problem i get :
I go to certain websites and I get this error with firefox.
This Site requires that JavaScript be enabled.
It is enabled.
This is the one of the errors in java script console with firefox.
Error: [Exception... "'Component does not have requested interface' when calling method: [nsIInterfaceRequestor::getInterface]" nsresult: "0x80004002 (NS_NOINTERFACE)" location: "<unknown>" data: no]
I have installed the java script from there home site and did a test and says everything is fine. Any ideas?
please helpHi 49ers,
Sorry not to have any real idea of how to help you out here, but this is a Java forum, not JavaScript.
Some Firefox expert may stumble across your post and be able to offer some advice (I hope they do) but this isn't really the best place to post such questions.
Try here: http://www.webdeveloper.com/forum/forumdisplay.php?s=&forumid=3
Good luck!
Chris. -
This is my first post here, seeking some help with my java homework. I am required to create a program to write out a receipt for a pizza company: name of company, total number of pizzas, costs (including tax etc), and print out the receipt after taking an order from the customer.
This is a beginner's java class and my book isn't very good at explaining (mainly because it says "will be discussed in ch 14" when we're in ch 1-3 and it's an essential part of the program).
But anyways, if anyone is up right now, would be helpful for some help. I have a general idea of what I wanna do, but the program so far is very messy and incomplete and having trouble getting it to look nice and proper.well there were two ways of doing this, im only 2 weeks new in java so bear with me.....I was gonna set 3 classes, one appclass, one order form, and one receipt. I was told you can combine the order and receipt in 1 class, but I thought doing 3 woudl be better to help me learn more...anyways, I haven't worked on the appclass yet, but for the order I have a very messy set of codes. I know that it's wrong but it's a start, im looking for any input cause the book does not explain very much.
For the order class, I will be doing showinputdialog boxes for how many pizzas, the sizes, and the toppings. Here is what I have so far ( i know it is VERY messy and disorganized but I am a bit lost in where I should go next):
* @author AlexNguyen
* To take the order with number of pizzas and toppings
package project2;
import javax.swing.JOptionPane;
public class Order {
public int NumberOfPizzas;
public char Pepperoni;
public char Sausage;
public char Cheese;
public Order(int n) {
NumberOfPizzas = n;
JOptionPane.showInputDialog("Enter Number of Pizzas"));
String ptype; {
public void start();
public void takeOrder();
public void writeReceipt();
public void takeOrder();
ptype = Topping
public String selectPizza(char P, char S, char C) {
Pepperoni = P;
Sausage = S;
Cheese = C;
public void numPizza(int numberOfPizzas) {
num = numberOfPizzas;
JOptionPane.showInputDialog("Topping for Pizza?");
JOptionPane.showInputDialog("Pizza Size?");
JOptionPane.showInputDialog("Number of Pizzas?");
}
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