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How can i access a linked list that is implement by me form outside of class

I have a linked list that store bunch of instrument as an object. And i want to access and display it on a GUI. What are some good ways to access it instead of just create a method and return the list to the GUI.
Pls gives some advice.
I will be appreciated.

It depends if you mean the class or an instance of your class. If you mean a class its just an import. If you need an instance of a class there are other ways like making it static (quick and dirty) or using a singleton if just one copy is allowed.

class InstrumentDisplayPanel extends JPanel implements ActionListener {
JPanel status = new JPanel();
JPanel action = new JPanel();
JLabel name = new JLabel();
JLabel number = new JLabel();
JButton next = new JButton("next");
JButton previous = new JButton("previous");
InstrumentDisplayPanel() {
this.setPreferredSize(new Dimension(200,200));
DoublyLinkedList<Instrument> instrumentList = FileRead.loadInstrument();
Node tempNode = instrumentList.getFirstItem();
Item tempItem = (Item)tempNode.getItem();
name.setText(tempItem.getName());
number.setText(tempItem.getNumber());
status.add(name);
status.add(number);
action.add(next);
action.add(previous);
add(status);
add(action);
}
public void actionPerformed(ActionEvent event) {
if (event.getSource() == next) {
}
}
}

public static DoublyLinkedList<MusicSheet> loadMusicSheet(){
System.out.println("I am loading");
Scanner musicSheetInput = null;
try
{
musicSheetInput = new Scanner(new File("musicSheet.txt"));
}
catch(FileNotFoundException instrument)
{
System.out.println("File does Not Exist Please Try Again: ");
}
DoublyLinkedList<MusicSheet> musicSheetList = new DoublyLinkedList<MusicSheet>();
while (musicSheetInput.hasNextLine()){
String name = musicSheetInput.next();
String number = musicSheetInput.next();
String description = musicSheetInput.nextLine();
if(name.equals("GuitarSheet")){
musicSheetList.add(new GuitarSheet(name,number,description));
}
else if(name.equals("ViolinSheet")){
musicSheetList.add(new ViolinSheet(name,number,description));
}
else if(name.equals("CelloSheet")){
musicSheetList.add(new CelloSheet(name,number, description));
}
}
musicSheetList.display();
return musicSheetList;
}

Using hashmap to display data in JTextField and update it

Below is code that creates items that have code number name, price and quantity respectively.
public class StockData {
private static class Item {
Item(String n, double p, int q) {
name = n;
price = p;
quantity = q;
}
public String getName() {
return name;
}
public double getPrice() {
return price;
}
public int getQuantity() {
return quantity;
}
private final String name;
private final double price;
private int quantity;
}
public final static Map<String, Item> stock = new HashMap();
static {
stock.put("00", new Item("Bath towel", 5.50, 10));
stock.put("11", new Item("Plebney light", 20.00, 5));
stock.put("22", new Item("Gorilla suit", 30.00, 7));
stock.put("33", new Item("Whizz games console", 50.00, 8));
stock.put("44", new Item("Oven", 200.00, 4));
}
public static Map<String, Item> getStock() {
return stock;
}
public static String getName(String key) {
Item item = stock.get(key);
if (item == null) {
return null; // null means no such item
} else {
return item.getName();
}
}
public static double getPrice(String key) {
Item item = stock.get(key);
if (item == null) {
return -1.0; // negative price means no such item
} else {
return item.getPrice();
}
}
public static int getQuantity(String key) {
Item item = stock.get(key);
if (item == null) {
return -1; // negative quantity means no such item
} else {
return item.getQuantity();
}
}
public static void update(String key, int extra) {
Item item = stock.get(key);
if (item != null) {
item.quantity += extra;
}
}
}
And here is a different class that is a part of my gui which looks like: http://imgur.com/Jhc4CAz
and my idea is you type the code of an item eg. 22 then type how many you would like to add to the stock so for example 5 you click add so it adds to the variable but immidiately updates the text in the box as you can see on the screen.
I really got myself puzzled with hashmap / list I don't think there is a point copying all the data from hashmap to list and pretty much multiplying it there must be a better way to achieve this.
public class UpdateStock extends JFrame implements ActionListener {
JTextField stockNo = new JTextField(4);
JButton addButton = new JButton("ADD");
JSpinner quantitySlider = new JSpinner();
JTextArea catalog = new JTextArea(7, 30);
List items = new ArrayList();
public UpdateStock(){
setLayout(new BorderLayout());
setBounds(100, 100, 450, 500);
setTitle("Update Stock");
setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
JPanel top = new JPanel();
add("North", top);
JPanel middle = new JPanel();
add("Center", middle);
top.add(stockNo);
top.add(quantitySlider);
top.add(addButton);
catalog.setLineWrap(true);
catalog.setWrapStyleWord(true);
catalog.setEditable(false);
middle.add(new JScrollPane(catalog));
for(String key : StockData.getStock().keySet()) {
catalog.append("Item: " + key +"\n");
items.add(StockData.getName(key));
catalog.append("Name: " + StockData.getName(key) +
" Price: " + StockData.getPrice(key) +
" Qty: " + StockData.getQuantity(key)+"\n");
}
setResizable(false);
setVisible(true);
}
}

your code immediately puts text in the JTextArea because you tell it to. It's right there in the constructor:
for(String key : StockData.getStock().keySet()) {
catalog.append("Item: " + key +"\n");
items.add(StockData.getName(key));
catalog.append("Name: " + StockData.getName(key) +
" Price: " + StockData.getPrice(key) +
" Qty: " + StockData.getQuantity(key)+"\n");
}
If you want to wait until the user picks an item before setting any text, then register an ActionListener on addButton using its addActionListener() method. Use that listener's actionPerformed() method to set the text. Don't forget to remove the code shown above from your constructor, too.
I see you already know about the ActionListener class, since it's implemented by UpdateStock, but it's a little weird (though totally valid!) to do it that way; I don't think I've seen many subclasses of JFrame implement it directly. The usual pattern is to use an anonymous ActionListener and just register that instead. If you really want to use UpdateStock as an ActionListener, then you'll need an actionPerformed() method defined in UpdateStock and you'll need to register this as an action listener on your button.

ArrayList , JFrame, JLabel

I am trying to create and simple program that has the user input 4 fields using the JFrame and textfields. Save those into a class. Put that class into an ArrayList (So they have the option to delete / or add more "classes" to it later). Then display all the contents of the ArrayList on one Frame.
I got the four fields to work I believe , but the part where the ArrayList contents are supposed to be displayed is not working ( I get a blank frame ).
this is my add into the arrayList ..
public void newEntryFrame()
{
JFrame entryFrame = new JFrame("Passafe");
entryFrame.setVisible(true);
entryFrame.setSize(500, 500);
entryFrame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
entryFrame.setLocationRelativeTo(null);
entryFrame.setLayout(new FlowLayout());
header.setFont(new Font("Serif", Font.BOLD, 16));
entryFrame.add(header);
entryFrame.add(nameLabel);
entryFrame.add(nametf);
entryFrame.add(usernameLabel);
entryFrame.add(usernametf);
entryFrame.add(passwordLabel);
entryFrame.add(passwordtf);
entryFrame.add(descriptionLabel);
entryFrame.add(descriptiontf);
entryFrame.add(enterButton);
enterButton.addActionListener(this);
}
public void actionPerformed(ActionEvent event)
{
Object source = event.getSource();
if(source == enterButton)
{
name = nametf.getText();
description = descriptiontf.getText();
username = usernametf.getText();
password = passwordtf.getText();
totalEntries++;
JOptionPane.showMessageDialog(null, "SAVED");
}
else if(source == okButton)
{
JOptionPane.showMessageDialog(null, "Ok Button Works");
}
}
this is what I have to display the arrayList.
public void viewEntryFrame()
{
JFrame viewFrame = new JFrame("Passafe");
viewFrame.setSize(500, 500);
viewFrame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
viewFrame.setLocationRelativeTo(null);
viewFrame.setLayout(new FlowLayout());
viewFrame.add(listHeader);
newEntry tempView = new newEntry();
for(int i = 0; i < totalEntries; ++i)
{
tempView = entries.get(i);
viewFrame.add(tempView.display);
}
viewFrame.add(okButton);
okButton.addActionListener(this);
viewFrame.setVisible(true);
}
I might be doing this completely wrong if so could you point me in the right direction.

I don't think you ever called setContentPane() A JFrame has only one component in the main part of it. You have to create a JPanel to which you can add all of the components you want, then add that to your JFrame.
JFrame frame = new JFrame();
JPanel panel = new JPanel();
panel.add(/**whatever you want in your JFrame**/);
//...
panel.add(/**whatever you want in your JFrame**/);
frame.setContentPane(panel);

You never seem to be adding anything to your entries list...
public void actionPerformed(ActionEvent event)
{
Object source = event.getSource();
if(source == enterButton)
{
name = nametf.getText();
description = descriptiontf.getText();
username = usernametf.getText();
password = passwordtf.getText();
totalEntries++;
// Nope, nothing here...
JOptionPane.showMessageDialog(null, "SAVED");
}
//...
}
Also, this is very dangrouos...
newEntry tempView = new newEntry();
for(int i = 0; i < totalEntries; ++i)
{
tempView = entries.get(i);
viewFrame.add(tempView.display);
}
Rather the relying on the actual side of the ArrayList, you relying on some other variable, which may or may not equal the actual size, instead you should be using ArrayList#size, for example
for(int i = 0; i < entries.size(); ++i)
{
newEntry tempView = entries.get(i);
viewFrame.add(tempView.display);
}
Or if you're using Java 5+...
for(newEntry tempView : enties)
{
viewFrame.add(tempView.display);
}

Item Listeners Error

I'm having an issue with Item Listeners.It's the first time I'm using it, so far all I've used is the Item Event. I was wondering if you could clear up what the difference between those two, as well point me out what I'm doing wrong.
My issue is on line 46 the line starting with: Object source = toppingList.getSource(); and the error I get is 'Cannot find symbol'.
I'm thinking I'm using the wrong item before the getSource();, I thought that the toppingList was the correct item, I can't see which other item I could put in it's place.
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class Pizza extends JFrame{
FlowLayout flow = new FlowLayout();
JComboBox pizzaBox = new JComboBox();
JLabel toppingList = new JLabel("Topping List");
JLabel aLabel = new JLabel("Paulos's American Pie");
JTextField totPrice = new JTextField(10);
int[] pizzaPrice = {7,10,10,8,8,8,8};
int totalPrice = 0;
String output;
int pizzaNum;
public Pizza()
{
super("Pizza List");
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setLayout(flow);
pizzaBox.addItemListener((ItemListener) this);
add(toppingList);
pizzaBox.addItem("cheese");
pizzaBox.addItem("sausage");
pizzaBox.addItem("pepperoni");
pizzaBox.addItem("onion");
pizzaBox.addItem("green pepper");
pizzaBox.addItem("green olive");
pizzaBox.addItem("black olive");
add(pizzaBox);
add(aLabel);
add(totPrice);
}
public static void main(String[] arguments)
{
JFrame frame = new DebugFourteen3();
frame.setSize(200, 150);
frame.setVisible(true);
}
public void itemStateChanged(ItemEvent[] list)
{
Object source = toppingList.getSource();
if(source == pizzaBox)
{
int pizzaNum = pizzaBox.getSelectedIndex();
totalPrice = pizzaPrice[pizzaNum];
output = "Pizza Price $" + totalPrice;
totPrice.setText(output);
}
}
}

Gui elements do not have any getSource, it is a method of the event - telling you which gui element generated the event. But you know what the source of the event is, since in your constructor you wrote:
pizzaBox.addItemListener((ItemListener) this);
and you did not add this to any other gui element. So you cannot get events from any other gui element. So do not test for it.
But there are other issues:
Your PizzaBox should implement ItemListener:
public class Pizza extends JFrame implement ItemListener
and then just write
pizzaBox.addItemListener(this);
If you want to listen to multiple elements, add separate anonymous listener for each (and Pizza does not implement ItemListener)
// in your constructor:
pizzaBox.addItemListener(new ItemListener() {
public void itemStateChanged(ItemEvent e) {
if (e.getStateChange() == ItemEvent.SELECTED) {
pizzaNum = pizzaBox.getSelectedIndex(); // in your code you have int pizzaNum but at the same time, pizzaNum is a class variable, probably an error
// and so on
}
}
});
or you can move the code to a separate method
public class Pizza extends JFrame {
public Pizza() {
:
pizzaBox.addItemListener(new ItemListener() {
public void itemStateChanged(ItemEvent e) {
pizzaBox_itemStateChanged(e);
}
});
:
}
private void pizzaBox_itemStateChanged(ItemEvent e) {
if (e.getStateChange() == ItemEvent.SELECTED) {
pizzaNum = pizzaBox.getSelectedIndex();
// and so on
}
}
:
}

You need to implement ItemListener with class. For details go through this tutorial
public class Pizza extends JFrame implements ItemListener{
.....
public Pizza(){
pizzaBox.addItemListener(this);// Here this is enough
....
}
// itemStateChanged should write as follows
public void itemStateChanged(ItemEvent e) {
//It will be enable if checkbox is selected
if (e.getStateChange() == ItemEvent.SELECTED) {
int pizzaNum = pizzaBox.getSelectedIndex();
totalPrice = pizzaPrice[pizzaNum];
output = "Pizza Price $" + totalPrice;
totPrice.setText(output);
}
}
}

InputVerifier don't display each component icon(lable)

I have a form that set a input verifier to it.
I want when a user type a correct value for a text field and want to go to other text field, a check icon should be display besides of text field.
But now in my code, when user type a correct value on first text field an go to other, Two icons displayed together!
public class UserDialog extends JDialog {
JButton cancelBtn, okBtn;
JTextField fNameTf, lNameTf;
JRadioButton maleRb, femaleRb;
ButtonGroup group;
JLabel fNameLbl, fNamePicLbl, lNameLbl, lNamePicLbl, genderLbl, tempBtn, temp3;
public UserDialog() {
add(createForm(), BorderLayout.CENTER);
setDefaultCloseOperation(DISPOSE_ON_CLOSE);
setLocation(400, 100);
pack();
setVisible(true);
}
public JPanel createForm() {
JPanel panel = new JPanel();
ImageIcon image = new ImageIcon("Check.png");
okBtn = new JButton("Ok");
cancelBtn = new JButton("Cancel");
tempBtn = new JLabel();
fNameLbl = new JLabel("First Name");
fNamePicLbl = new JLabel(image);
fNamePicLbl.setVisible(false);
lNameLbl = new JLabel("Last Name");
lNamePicLbl = new JLabel(image);
lNamePicLbl.setVisible(false);
genderLbl = new JLabel("Gender");
maleRb = new JRadioButton("Male");
femaleRb = new JRadioButton("Female");
temp3 = new JLabel();
group = new ButtonGroup();
group.add(maleRb);
group.add(femaleRb);
fNameTf = new JTextField(10);
fNameTf.setName("FnTF");
fNameTf.setInputVerifier(new MyVerifier(new JComponent[]{maleRb, femaleRb, okBtn}));
lNameTf = new JTextField(10);
lNameTf.setName("LnTF");
lNameTf.setInputVerifier(new MyVerifier(new JComponent[]{maleRb, femaleRb, okBtn}));
panel.add(fNameLbl);
panel.add(fNameTf);
panel.add(fNamePicLbl);
panel.add(lNameLbl);
panel.add(lNameTf);
panel.add(lNamePicLbl);
panel.add(genderLbl);
JPanel radioPanel = new JPanel(new FlowLayout(FlowLayout.LEFT));
radioPanel.add(maleRb);
radioPanel.add(femaleRb);
panel.add(radioPanel);
panel.add(temp3);
panel.add(okBtn);
panel.add(cancelBtn);
panel.add(tempBtn);
panel.setLayout(new SpringLayout());
SpringUtilities.makeCompactGrid(panel, 4, 3, 50, 10, 80, 60);
return panel;
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
new UserDialog();
}
});
}
public class MyVerifier extends InputVerifier {
private JComponent[] component;
public MyVerifier(JComponent[] components) {
component = components;
}
#Override
public boolean verify(JComponent input) {
String name = input.getName();
if (name.equals("FnTF")) {
String text = ((JTextField) input).getText().trim();
if (text.matches(".*\\d.*") || text.length() == 0) {
//disable dependent components
for (JComponent r : component) {
r.setEnabled(false);
}
return false;
}
} else if (name.equals("LnTF")) {
String text = ((JTextField) input).getText();
if (text.matches(".*\\d.*") || text.length() == 0) {
//disable dependent components
for (JComponent r : component) {
r.setEnabled(false);
}
return false;
}
}
//enable dependent components
for (JComponent r : component) {
r.setEnabled(true);
}
fNamePicLbl.setVisible(true);
lNamePicLbl.setVisible(true);
return true;
}
}
}
}
Updated
public class MyVerifier extends InputVerifier {
private JComponent[] component;
public MyVerifier(JComponent[] components) {
component = components;
}
#Override
public boolean verify(JComponent input) {
String name = input.getName();
if (name.equals("FnTF")) {
String text = ((JTextField) input).getText().trim();
if (text.matches(".*\\d.*") || text.length() == 0) {
return false;
}
} else if (name.equals("LnTF")) {
String text = ((JTextField) input).getText();
if (text.matches(".*\\d.*") || text.length() == 0) {
return false;
}
}
return true;
}
#Override
public boolean shouldYieldFocus(JComponent input) {
boolean isValidDate = verify(input);
if (isValidDate) {
for (JComponent r : component) {
r.setEnabled(true);
}
} else {
for (JComponent r : component) {
r.setEnabled(false);
}
}
return isValidDate;
}

But now in my code, when user type a correct value on first text field
an go to other, Two icons displayed together!
Because you did so: (Read the comments)
public boolean verify(JComponent input) {
String name = input.getName();
if (name.equals("FnTF")) {
// your code
}
} else if (name.equals("LnTF")) {
// your code
}
//enable dependent components
for (JComponent r : component) {
r.setEnabled(true);
}
/* And Now we are here */
fNamePicLbl.setVisible(true);
lNamePicLbl.setVisible(true);
// making visible two of them at once as soon as verify is called
// on any one of the components, verifier is registered
return true;
}
setVisible should be controlled by the if-else condition too. For your better understanding you need to do something like this:
if (text.matches(".*\\d.*") || text.length() == 0) {
// your code
}
else
{
fNamePicLbl.setVisible(true);
}
Second Issue:
fNameTf.setInputVerifier(new MyVerifier(new JComponent[]{maleRb, femaleRb, okBtn}));
lNameTf = new JTextField(10);
lNameTf.setName("LnTF");
lNameTf.setInputVerifier(new MyVerifier(new JComponent[]{maleRb, femaleRb, okBtn}));
The MyVerfier has the common code to verify both input field. But you are creating two instances of it with same instances of components. Create one and set it as the input verifier of the two field.
You might want to create two different InputVerifier class for the two Text Field. FnTFVerifier and LnTFVerifier. Then put your verification code that relates them e.g., enabling the radio buttons and showing the label with check.png. most of the if-else checking will go-away.
But I think, this should not really be the preferable way. As the two text field has the common functionality, one InputVerifier class and instance is sufficient. you would have to just encapsulate the input text field and related cehckLabel to one component, then register the InputVerifier instances to this component.
Third issue: you are misusing verify function:
The verify function is meant to be used for nothing but verify data: whether data is valid or not with user required condition. It should do nothing more. InputVerifier has another function boolean ShouldYieldFocus(Jcomponent): Before focus is transfered to another Swing component that requests it, the input verifier's shouldYieldFocus method is called, which decides whither the component under verification should lose focus or not. Focus is transferred only if this method returns true. You should however write the required state change of components inside this function.
public boolean shouldYieldFocus(JComponent input) {
boolean isDataValid = verify(input);
if(isDataValid); //do stuff
return isDataValid; // if verify is true(valid) return true;
}