Calculating Sum Of Elements Within JList
Mar 25, 2015
I'm currently in the process of creating a shopping cart simulation. The main GUI consists of two lists, one is a list of the inventory. (products stored within a .dat file which is automatically loaded upon launch) The other is blank and is to model my shopping basket. The idea is to be able to scan items from my inventory into the checkout basket. As this is happening i want a text field i created to dynamically update with the cost of all the items in the basket.
Below is the method for my scan button, which is supposed to perform the above :
public void actionPerformed(ActionEvent evt) {
//Get the newly added list values.
JList list = productList.getSelectedValuesList();
double totalAddedValue = 0.0;
double oldCartValue = 0.0;
[code]...
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Mar 14, 2014
I know there was a change in the later versions of Java where the C++ equivalent of a <template type> was added. Unfortunately the change has 'broken' my older code. If I have a JList and I want to add elements to it then now I should specify the type e.g., the list will store Strings. When I do this and then add data to the list (or actually the list model) the code is ''fixed". However if after adding those new elements to the list I later need to add more elements, which isn't unreasonable for a list...to have elements added dynamically at run time then I again get the same compiler error message that I haven't correctly specified the type:
// Error message during compilation
Note: Driver.java uses unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.
// My code
// Problem here: I try to add new elements to the list. It's the very last line of the method that results in the error. I tried various things such as:
// model.addElement(<String> s);
// but so far nothing has worked. How do I add new elements to the list (model)?
public static void m2(JList <String> list)
{
String s;
int i;
String [] array = new String[10];
[Code] ....
// Code is OK: Create the array of strings to add to constructor of the JList
public static String[] m1(){ String s;
int i;
String [] array = new String[10];
for (i = 0; i < 5; i++)
array[i] = i + "*"; return(array);
[Code] ....
// The change I had to make when compiling under the newer version of Java to indicate that the list would store strings
// Things are okay here now but then when I try to add new elements to the model via method 'm2' that's where I get the compiler error
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Feb 5, 2015
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
public class array
{
public static void main(String[] args)
[Code] ...
Is there a way to write this, where, alpha is one array.
Write a program that declares an array "alpha" of 50 elements of type "double". Initialize the array so that the first 25 elements are equal to the square of the index variable and the last 25 elements are equal to three times the index variable. Output the array so that 10 elements per line are printed.
If I have an array of 50 integers, can I break that to read in lines of 10?
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Jan 12, 2015
I am trying to make a 2d array that keeps track of comparison counts. what I have so far works ok but writes over the previous elements with 0. can't seem to find where I am re-initializing the previous elements.
//this is one of my fill sort arrays
public void fillSelectionArray(int index, long countSum) {
//rand = new Random( );
//for ( int i = 0; i < listsize; i++) {
selectionList[ index -1] = countSum;
// }
[Code] ....
I know I am missing something just not sure what.
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Apr 22, 2015
I don t know why this throw a nullpointerexception. i want to add rows from mysql database to my jlist, this is my method populateJlist().
public void populateJlist() throws SQLException {
conn= DriverManager.getConnection("jdbc:mysql://localhost:3306/agenda","root","");
DefaultListModel m = new DefaultListModel();
statement=conn.prepareStatement("SELECT *FROM apunte");
rs=statement.executeQuery();
String itemCode;
[code]...
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Apr 18, 2014
Can I use Jlist instead of Jtable for showing database table data (select * from employee) in my code?
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Dec 18, 2014
I currently have some code using a JFrame. I am trying to access the items in a JList to save them in a TXT file. For this, I am using a "for" loop. The problem is, is that when I try to access the list items, I can't access them. The way I am trying to access the items is by using:
Java Code: listRight.getModel().getSize(); mh_sh_highlight_all('java');
BUT, I can't seem to get this to work. I tried to place this for loop everywhere and I can't access it. I tried accessing it under "public class Window", "private JFrame frmPcPartBuilder", "public static void main(String[] args)", "public void Initialize()" and I can't seem to access the JList. I basically have a save button that saves the list to a text file and the code I am trying to write is called by this button.
Java Code: package com.cooksys.assessment;
import java.awt.EventQueue;
import javax.swing.DefaultListModel;
import javax.swing.JFrame;
import javax.swing.JButton;
[code]....
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Nov 5, 2014
I have a empty JList in which I hit a button LOAD DATA which should load all the data. but once I load data i try to fill in the List but I keep getting errors.
String[] aos = new String[itrList.size()];
itrList.toArray(aos);
//JList listFAIL = new JList(aos);
//list = new JList(itrList.toArray());
//list.removeAll();
list.setListData(aos);
JScrollPane s = new JScrollPane(list);
I have tried doing setListData and i get a error;
And if i do new Jlist it doesn't change the data.
The List does fill as i have a checker for that.
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Jan 13, 2014
I am trying to populate a Jlist for information stored on a database. The database contains football club names, but instead of being populated with their names it just has a hexadecimal reference ( Club@183357c4 ) for each club object.
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Mar 13, 2015
I was programming a crossword in java and needed to hava a list of words from where to choose in case i wanted to fill my generated crossword but I don't know how to upload that txt dictionary in the first place.
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Apr 14, 2015
I am currently creating a Twitter Application within Java Swing using JSON. I have the JList populating with Home feeds but i also want to get Images displaying next to the Text ...
currently all i am getting is [URL] ....
So a am able to get the URL Link but getting that to a Image seems to be the problem
/ArrayLists
final ArrayList<String> TweetArray = new ArrayList<String>(); //Array List for Users Tweets..
final static ArrayList<String> incomingTweets = new ArrayList<String>(); //ArrayList for Incoming Tweets.
ArrayList<String> arrayImages = new ArrayList<String>();//ArrayList for incoming Tweet Profile Images
private Map<String, ImageIcon> imageMap;
[Code] ....
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Aug 9, 2014
how to add values from Jtextbox(name) to JList and display the selected values from Jlist.
import java.awt.*;
import java.awt.event.*;
import java.awt.Color;
import javax.swing.*;
import javax.swing.event.*;
import javax.swing.border.*;
import javax.swing.DefaultListModel;
[Code] ....
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Oct 23, 2014
is there a good way to change the color of a JList item that isn't selected? I'm throwing my hand at building a client/server chat app and on the client side, I need to highlight the name of the person (which is in a JList) who has sent a message to the client GUI.
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Sep 16, 2014
I am currently writing a chess application in Java swing. For the GUI part, I have one MainWindow class, and one ChessBoard class. The MainWindow has a main panel, in which is contained 1) a panel containing the chessboard from the chessboard class (a grid layout array of 64 JLabels), 2) a JLabel status bar, and 3) a JList to hold the moves of the game. I have a movePiece method in the chessboard class, which I would like to add the move and question to the moves list, which is contained in the main window class.
However, since JList is some special type, I can't make it static ( that gives me an error ). I also tried creating a method in the main window class to add a move to the list, which I would then access via the chessboard class. However, I can't make the method static, because it is referencing a non-static variable ( the JList ), and since the Main window class already has an object of the chessboard class, trying to create a main window object in the chessboard class creates a stack overflow error.
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Mar 15, 2015
I am able to update the array holding the items but I don't know how to refresh the JList to include all the new items in the array.
Code for GUI:
import java.awt.ScrollPane;
import java.awt.event.ActionListener;
import javax.swing.*;
public class ListView extends JFrame{
HobbyList stuff = new HobbyList();
[Code] .....
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Aug 21, 2014
I am trying to use the JList to display a list of students. Now, each student has a first name, last name and course taken. each courses taken by the student has its' own name, level and idNumber. For now, I am just trying to create my own custom JList model for the students. I have the custom model as well as the button event calling it. Unfortunately, when I click the button to display the student info added, the component is NOT fired up!..
I am not sure what I have done wrong regarding creating the component because I can display the information on the console and the list contains everything I have added but just to display it on the component is NOT working. I have broken the codes into sub classes, you can add the classes to the same package or create sub packages to insert individual classes.
The student class
public class Student {
private String studentName;
private String studentID ;
public String getStudentName(){
return studentName;
[Code] ....
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Sep 20, 2014
I have a program I am creating in Eclipse. In my JFrame window, I am adding a JList object that I want to load with an EnumMap that I have created in a separate 'enum' class.
In my JFrame, I have a method called 'loadJList()' in which I want to iterate through the EnumMap and load the keys & values.
Here's what I've tried
In my EnumMap class, I've done the following ...
Java Code:
public enum MyEnumMap {
.....//created map values & keys, getter() and setter()
public Enum<MyEnumMap> getEnum() {
return this;
}
} mh_sh_highlight_all('java');
I imported my EnumMap program in my JFrame program and tried something like ...
Java Code:
public void loadJList() {
for(Enum<?> e: myEnumMap.values()) {
list.add ....
}
} mh_sh_highlight_all('java');
Which does not work. I've scoured the internet a bit but sources on EnumMap are limited, at least ones I can understand (first time trying to use this).
I also need to elaborate on the key of the EnumMap (they are cities, I'd like to add the state or country). For example
LASVEGAS, 749.99
I would want displayed as
Las Vegas, Nevada .... 749.99
My ultimate goal here is to access my EnumMap in my JFrame program to dynamically load a JList object.
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May 2, 2015
I have an addressBook GUI where I have a JList that populates with the contacts names, and once I double click a contacts name I'm wanting to fill the textfields with the contacts corresponding data.
ex) ContactType: Family (enum), Name: Zoidberg, Address: 111 Space Drive, City: New York City, etc...
I've got it to where I select open from the JMenu, it populates the JList, but once I select a contacts name, all the textfields are populated, but only with the contacts name
ex) Name: Zoidberg, Address: Zoidberg, City: Zoidberg, etc....
What am i doing wrong here, and how can i fix it to where it fills out the correct data?
Here's my code so far:
public class AddressBookGUI extends JFrame {
private final int WIDTH = 450;
private final int HEIGHT = 300;
private JLabel currentlySelected;
private JTextField contactTypeTextField;
[code]...
I'm certain the logic is messed up near the end where i set all text fields to the index, because no matter what field i want to fill it's at it's going to set it to whatever index I select, but I don't know how to fix it.
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Oct 8, 2014
I would like to create a sub menu for every list item in a Jlist. I need the UI like avast interface. If we hover over an list item, its sub menu should be shown. I attempted to put an sub menu but didn't work. Is this possible in Swing?
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Sep 29, 2014
I am attempting to use JLists to complete a program that models how operating systems manage processes. A quick synopsis of what it is supposed to do. Each process is to have a priority level (I chose to do 1 -3 with 3 being the most important) and there are supposed to be three lists. One for ready processes, blocked processes, and a running process.
My issues:
1) when I block a process it does indeed switch lists but when it is copied into the blocked list it pulls the element number instead of what the actual process number is. For ex: Say the ready list has 5 processes / I delete 2 / Leaving process 1, 2, 5. When I block 5, it gets registered in the blocked list as process 2.
2) I can't figure out how to give a label to each of my scroll panels (JLists) to signify which box is ready / blocked / and running
3) My switch button - I have commented in what I need to do but don't know how I am going to do it.
Below are my files:
Main
import java.util.Comparator;
import java.util.PriorityQueue;
import java.util.Queue;
import javax.swing.JFrame;
import javax.swing.JTextArea;
public class PQueue {
public static void main(String[] args) throws InterruptedException {
[Code] ....
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Nov 9, 2014
I have a JList<Object> in my code (it actually takes JLabels) called imageList, and I've given it a custom CellRenderer using the following code:
cellRenderer = new DefaultListCellRenderer() {
private static final long serialVersionUID = 1L;
@Override
public Component getListCellRendererComponent(JList<?> list,
Object value, int index, boolean isSelected,
boolean cellHasFocus) {
[Code] .....
However, when I click anywhere on the JList, nothing gets printed to the console, which suggests that the mousePressed() method isn't being invoked. I think it's a problem with the CellRenderer, because I have similar code elsewhere that works, the only difference being I don't use a custom CellRenderer.
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Aug 31, 2014
I'm new to programming and java and I'm trying to understand how exactly this piece of code works and what exactly does. I'm trying to make my first GUI application and to read some person details from a file and then put the result in a Jlist.
private static final String SEPARATOR = ",";
public static ArrayList<Speaker> getAllMembers() {
ArrayList<Member> members = new ArrayList<Member>();
try {
File file = new File(Resources.MEMBERS_TXT);
Scanner fileReader = new Scanner(file, "utf-8");
String[] properties;
[Code] ....
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Sep 19, 2014
I am trying to create a GUI interface in swing which consists of four classes: a GUI class, which creates a main JPanel, a label, and a JList, which it takes from the second class, a MovesList class that contains a JList and the stuff needed to interface with it. It also has a main class, which basically just creates an object of the GUI class for the main window, and an Other class from which I would like to be able to add an item to the JList. I created methods in the MovesList class to get each component (like getMoveslist, or getMovesListScrollPane), which I then used to create the JList in the GUI class. I also created an addMove method so that I can add an item to the JList from any class through a MovesList object. However, this addMove method only works when called from the GUI or MovesList classes -- it does nothing when I collect from the Other class.
Here is my code:
//Main class
public class TestProject {
public static void main(String[] args) {
GUI mainWindow = new GUI();
mainWindow.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
[Code] ....
When I run this code, I get a window with a JLabel that says "Moves," and a JList that contains five elements -- test 1-test 5, but not a sixth "test from other class." ( using the add move method ) However, when I click on the window, the addMove method is also called, and successfully adds "test 6" to the list.
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Jan 28, 2015
New to Java Swing. What I am trying to achieve here is to create an instance of the class used to populate the DefaultListModel when a JList item is selected. All examples I have seen show how to return the text displayed in the JList which really is of no practical use.
I have achieved what I want to achieve in that I am successfuly creating the selected object within my ListCellRenderer class.
For the purpose of testing I am using a call to the JOptionPane.showMessageDialog method to display the id of the selected object.
So, I launch the JFrame, the JList is populated, I select an item from the JList and the id value is displayed in the prompt. All this works fine except for one thing.
When I click OK on the JOptionPane.showMessageDialog prompt, the prompt disappears and reappears. The system seems to be in a loop. It is behaving as if the change or click event handler on the JList keeps firing.
This happens even without the creation of the object:
BookEntry be = (BookEntry)list.getModel().getElementAt(list.getSelectedIndex());
I have scoured the code and object properties to see if I can figure out where this behaviour is coming from without success.
All there is in the JFrame design view is a single JList with a variable name of "list". Everything else is in code as below:
Here is the .java code. Its not that complex
import java.awt.Color;
import java.awt.Component;
import javax.swing.JLabel;
import javax.swing.JList;
import javax.swing.JOptionPane;
import javax.swing.ListCellRenderer;
import javax.swing.DefaultListModel;
public class NewJFrame3 extends javax.swing.JFrame {
[Code] .....
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Oct 23, 2014
USING A WHILE OR A DO-WHILE LOOP write a program to compute PI using the following equation:
PI = 3 + 4/(2*3*4) - 4/(4*5*6) + 4/(6*7*8) - 4/(8*9*10) + ...
Allow the user to specify the number of terms (5 terms are shown) to use in the computation. Each time around the loop only one extra term should be added to the estimate for PI.
Alter your solution from part one so that the user is allowed to specify the precision required between 1 and 8 digits (i.e. the number of digits which are correct; e.g. to 5 digits PI is 3.14159), rather than the number of terms. The condition on the loop should be altered so that it continues until the required precision is obtained. Note that you need only submit this second version of the program (assuming you have it working).
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Sep 14, 2014
I'm trying to calculate sin(x) without using Math.sin(x). The formula for sin(x) is: x - x^3/3! + x^5/5! ... I can't seem to get the coding for the alternating +/- right. Here's my program:
import java.util.Scanner;
import java.lang.Math;
class Sin
{
public static void main(String[] args)
{
Scanner kb = new Scanner(System.in);
int n, c, fact = 1, count = 1;
double x, sum = 0, sum_sin = 0, result;
[Code] ....
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