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Re: reference to non-static variable from a static context..problems!
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Posted: Mar 26, 2004 6:35 AM
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here are the codes,
the java file called Diary that i've been referring to is actually called GUI.java, which canbe seen below
there are 2 more JAVA files, which are called Digital.java and Diary.java (this is the one called diary.java, but not relavant to what we've been discussing about in this thread).
digital.java contanis the JtabbedPane , the one containing the main.
diary.java is one that controls saving and raeding files and creating calendar screens.. but i found them irralevent to post, so here are the two important ones that is causing the problem
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THIS IS THE FILE USER.JAVA
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import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;
import java.util.*;
import java.text.Collator;
public class User extends JPanel implements ListSelectionListener {
public JList usersList;
private DefaultListModel usersModel;
public String userName = new String("Default");
private JButton deleteButton = new JButton("Delete");
private JTextField nameField;
private JButton addButton = new JButton("Add") ;
private JButton okButton = new JButton("OK");
private JLabel selectNote =new JLabel("Please select the user name!",JLabel.CENTER);
int i = 1; //this "i" variable will be used in the sortUser method
private GUI guiData;
public User() {
usersModel = new DefaultListModel();
usersModel.addElement("Default");
//Create the list and put it in a scroll pane.
usersList = new JList(usersModel);
usersList.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
usersList.setSelectedIndex(0);
usersList.addListSelectionListener(this);
usersList.setVisibleRowCount(5);
usersList.setPreferredSize(new Dimension(200, 200));
JScrollPane usersListScrollPane = new JScrollPane(usersList);
AddListener addListener = new AddListener(addButton);
addButton.addActionListener(addListener);
addButton.setEnabled(false);
deleteButton.addActionListener(new DeleteListener());
okButton.addActionListener(new OkListener());
nameField = new JTextField(10);
nameField.addActionListener(addListener);
nameField.getDocument().addDocumentListener(addListener);
String name = usersModel.getElementAt(
usersList.getSelectedIndex()).toString();
//Create a panel that uses BoxLayout.
JPanel mainpanel = new JPanel();
mainpanel.setLayout(new BorderLayout());
JPanel topPanel = new JPanel();
topPanel.add(new Label("USER SELECTION SCREEN"));
JPanel menuPanel = new JPanel(new GridLayout(2, 3));
menuPanel.add(nameField);
menuPanel.add(addButton);
menuPanel.add(deleteButton);
menuPanel.add(selectNote);
menuPanel.add(okButton);
mainpanel.add(topPanel, BorderLayout.NORTH);
mainpanel.add(usersListScrollPane, BorderLayout.CENTER);
mainpanel.add(menuPanel, BorderLayout.SOUTH);
add(mainpanel);
userName = userName;
}
class DeleteListener implements ActionListener {
public void actionPerformed(ActionEvent e) {
//This method can be called only if
//there's a valid selection
//so go ahead and remove whatever's selected.
int index = usersList.getSelectedIndex();
usersModel.remove(index);
int size = usersModel.getSize();
if (size == 0) { //Nobody's left, disable "delete".
deleteButton.setEnabled(false);
}
else { //Select an index.
if (index == usersModel.getSize()) {
//removed item in last position
index--;
}
usersList.setSelectedIndex(index);
usersList.ensureIndexIsVisible(index);
}
}
}
class OkListener implements ActionListener {
public void actionPerformed(ActionEvent e) {
userName = (String)(usersList.getSelectedValue());
JFrame frame = new JFrame();
String message = "The Following User has been Selected: " + userName;
JOptionPane.showMessageDialog(frame, message);
}
}
class AddListener implements ActionListener, DocumentListener {
private boolean alreadyEnabled = false;
private JButton button;
public AddListener(JButton button) {
this.button = button;
}
//Required by ActionListener.
public void actionPerformed(ActionEvent e) {
String name = nameField.getText();
if (name.length()>8) {
Toolkit.getDefaultToolkit().beep();
nameField.requestFocusInWindow();
nameField.selectAll();
JFrame frame = new JFrame();
String message = "Please make the name below 8 Letters";
JOptionPane.showMessageDialog(frame, message);
return;
};
//User didn't type in a unique name...
if (name.equals("") || alreadyInList(name)) {
Toolkit.getDefaultToolkit().beep();
nameField.requestFocusInWindow();
nameField.selectAll();
JFrame frame = new JFrame();
String message = "This User Already Exists";
JOptionPane.showMessageDialog(frame, message);
//shows a message if the user is already in the list
return;
}
int index = usersList.getSelectedIndex(); //get selected index
if (index == -1) { //no selection, so insert at beginning
index = 0;
} else { //add after the selected item
index++;
}
usersModel.insertElementAt(nameField.getText(), index);
//If we just wanted to add to the end, we'd do this:
//usersModel.addElement(employeeName.getText());
//Reset the text field.
nameField.requestFocusInWindow();
nameField.setText("");
//Select the new item and make it visible.
usersList.setSelectedIndex(index);
usersList.ensureIndexIsVisible(index);
sortUsers(); //view below for the "sortUser()" method
}
protected boolean alreadyInList(String name) {
return usersModel.contains(name);
}
//Required by DocumentListener.
public void insertUpdate(DocumentEvent e) {
enableButton();
}
//Required by DocumentListener.
public void removeUpdate(DocumentEvent e) {
handleEmptyTextField(e);
}
//Controls whether the Add Button should be enabled or not
public void changedUpdate(DocumentEvent e) {
if (!handleEmptyTextField(e)) {
enableButton();
}
}
private void enableButton() {
if (!alreadyEnabled) {
button.setEnabled(true);
}
}
private boolean handleEmptyTextField(DocumentEvent e) {
if (e.getDocument().getLength() <= 0) {
button.setEnabled(false);
alreadyEnabled = false;
return true;
}
return false;
}
}
public void sortUsers() {
usersModel = (DefaultListModel) usersList.getModel();
int numItems = usersModel.getSize();
String[] a = new String[numItems];
for (int i=0;i<numItems;i++){
a = (String)usersModel.getElementAt(i);
}
sortArray(Collator.getInstance(),a);
for (int i=0;i<numItems;i++) {
usersModel.setElementAt(a, i);
}
}
public void sortArray(Collator collator, String[] strArray) {
String tmp; if (strArray.length == 1) return;
for (int i = 0; i < strArray.length; i++) {
for (int j = i + 1; j < strArray.length; j++) {
if( collator.compare(strArray, strArray[j] ) > 0 ) {
tmp = strArray;
strArray = strArray[j];
strArray[j] = tmp;
}
}
}
}
//This method is required by ListSelectionListener.
public void valueChanged(ListSelectionEvent e) {
if (e.getValueIsAdjusting() == false) {
if (usersList.getSelectedIndex() == -1) {
//No selection, disable delete button.
deleteButton.setEnabled(false);
} else {
//Selection, enable the delete button.
deleteButton.setEnabled(true);
}
}
}
}
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THIS IS THE FILE: GUI.JAVA
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import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.util.*; //imports the required tools to use the program in a Graphical User Interface.
public class GUI extends JPanel {
User userData = new User();
private Diary data; //instantiates objects of other classes
//declares all the components that will be used the GUI
private JTextArea output = new JTextArea(20, 30);
private int year, month, day, daysinmonth;
private JLabel yearLabel = new JLabel("", JLabel.CENTER);
private JLabel monthLabel = new JLabel("", JLabel.CENTER);
private JLabel notice = new JLabel("Please save your diary entry!", JLabel.CENTER);
public JLabel diaryUserLabel = new JLabel("Diary ("+ userData.userName + ")",JLabel.CENTER);
private JButton nextMonth = new JButton(">");
private JButton previousMonth = new JButton("<");
private JButton nextYear = new JButton(">");
private JButton previousYear = new JButton("<");
private JButton[] dayButton = new JButton[31];
private JButton save = new JButton("Save");
private static final String[] nameofmonth = new String[] {
"January", "Febuary", "March", "April", "May", "June",
"July", "August", "September", "October", "November", "December"
};
public GUI() {
data = new Diary();
for (int i=0; i<dayButton.length; i++) {
dayButton = new JButton(""+(i+1));
} //creates buttons for the dates
fillout(); //fills in the buttons. see below to see how fillout function works
final int width = 800, height = 600;
setSize(width,height); //sets the size of the program screen
//assigns action to the buttons created.
ButtonListenerSave savel = new ButtonListenerSave();
save.addActionListener(savel);
ButtonListenerYear yearl = new ButtonListenerYear();
nextYear.addActionListener(yearl);
previousYear.addActionListener(yearl);
ButtonListenerMonth monthl = new ButtonListenerMonth();
nextMonth.addActionListener(monthl);
previousMonth.addActionListener(monthl);
ButtonListenerDay dayl = new ButtonListenerDay();
for (int i=0; i<dayButton.length; i++) {
dayButton.addActionListener(dayl);
}
// Let the user change the output.
output.setEditable(true);
// Place the list and input line in a panel.
JPanel contents = new JPanel();
contents.setLayout(new BorderLayout());
contents.add(diaryUserLabel, "North"); //add the heading "Diary (userName)"
JPanel mainpanel = new JPanel();
mainpanel.setLayout(new BorderLayout()); //the main panel is created
JPanel subpanel = new JPanel(); //a subpanel including the year,month is created
subpanel.setLayout(new BorderLayout());
JPanel panel1 = new JPanel();
panel1.setLayout(new GridLayout(2,3)); //makes panel1 into a grid of 2 by 3
panel1.add(previousYear); //
panel1.add(yearLabel); //
panel1.add(nextYear); //
panel1.add(previousMonth);// adds button& label that will change year,month
panel1.add(monthLabel); //
panel1.add(nextMonth); //
subpanel.add(panel1, "North"); //panel1 is added to the top of the subpanel
JPanel panel2 = new JPanel();
GridLayout layout = new GridLayout(5,7); //makes panel2 which is of grid 5 by 7
panel2.setLayout(layout);
for (int i=0; i<daysinmonth; i++) {
panel2.add(dayButton); //adds the day buttons into the grid.
}
subpanel.add(panel2, "Center");
mainpanel.add(subpanel, "West"); //the subpanel is added to mainPanel
JPanel panel3 = new JPanel(); //makes panel 3
panel3.setLayout(new BorderLayout());
panel3.add(notice, "North");
panel3.add(save, "Center"); // notice and save button added to the panel3
mainpanel.add(panel3, "South"); //panel 3 added to mainpanel
mainpanel.add(new JScrollPane(output), "East");
contents.add(mainpanel, "Center");
add(contents);
}
public void fillout () {
ArrayList A = data.getText();
output.setText("");
for (int i=0; i<A.size(); i++) {
output.append(A.get(i).toString()+"\n");
}
day = data.getDateInfo()[0];
month = data.getDateInfo()[1];
year = data.getDateInfo()[2];
daysinmonth = data.getDateInfo()[3];
//receives the information about day month and year from data.getdateinfo
monthLabel.setText(nameofmonth[month-1]);
//using the month information, refer to array namefmonth to assign a label
yearLabel.setText(""+year);
for (int i=0; i<dayButton.length; i++) {
boolean bool = (i<daysinmonth)? true: false;
dayButton.setVisible(bool);
// controls visibility of day buttons. for example,
// in april, the day button for 31 will not appear
dayButton.setBackground(save.getBackground());
}
dayButton[day-1].setBackground(new Color(0,0,255));
}
// The descriptions of action that is assigned to the buttons above.
private class ButtonListenerDay implements ActionListener {
public void actionPerformed(ActionEvent evt) {
day = Integer.parseInt(evt.getActionCommand());
data = new Diary(day, month, year);
fillout();
//the day will be changed,
//and then the new values will be assigend to data. Then fillout again
}
}
private class ButtonListenerMonth implements ActionListener {
public void actionPerformed(ActionEvent evt) {
month = (evt.getActionCommand().equalsIgnoreCase("<"))? month-1: month+1;
data = new Diary(1, month, year);
fillout(); //similar to ButtonListenerDay, but month changed.
}
}
private class ButtonListenerYear implements ActionListener {
public void actionPerformed(ActionEvent evt) {
year = (evt.getActionCommand().equalsIgnoreCase("<"))? year-1: year+1;
data = new Diary(1, month, year);
fillout(); //similar to ButtonListenerDay, but year changed
}
}
private class ButtonListenerSave implements ActionListener {
public void actionPerformed(ActionEvent evt) {
ArrayList A = new ArrayList();
StringTokenizer st = new StringTokenizer(output.getText(), "\n");
while (st.hasMoreTokens()) {
A.add(st.nextToken());
}
data.setText(A);
data = new Diary(day, month, year);
fillout(); //saves the diary entry to the file.
}
}
}
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