I have 4 hours to complete my exercise but I get multiple "cannot be referenced from a static context" errors.
Here are these in full:
MainApp.java:281: error: non-static variable this cannot be referenced from a static context
list.addMouseListener(this);
^
MainApp.java:289: error: non-static method setBounds(int,int,int,int) cannot be referenced from a static context
setBounds(300, 300, 350, 150);
^
MainApp.java:292: error: non-static method getContentPane() cannot be referenced from a static context
Container cp = getContentPane();
^
MainApp.java:299: error: non-static variable this cannot be referenced from a static context
button1.addActionListener(this);
^
MainApp.java:326: error: non-static method pack() cannot be referenced from a static context
pack();
^
MainApp.java:328: error: non-static method setDefaultCloseOperation(int) cannot be referenced from a static context
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
^
MainApp.java:330: error: non-static method RentShop(String,Catalogs,DefaultListModel) cannot be referenced from a static context
RentShop("Film",cat,ListModel);
^
MainApp.java:343: error: non-static variable this cannot be referenced from a static context
list2.addMouseListener(this);
^
MainApp.java:351: error: non-static method setBounds(int,int,int,int) cannot be referenced from a static context
setBounds(300, 300, 350, 150);
^
MainApp.java:354: error: non-static method getContentPane() cannot be referenced from a static context
Container cp2 = getContentPane();
^
MainApp.java:363: error: non-static variable this cannot be referenced from a static context
button2.addActionListener(this);
^
MainApp.java:391: error: non-static method pack() cannot be referenced from a static context
pack();
^
MainApp.java:393: error: non-static method setDefaultCloseOperation(int) cannot be referenced from a static context
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
^
MainApp.java:395: error: non-static method RentShop(String,Catalogs,DefaultListModel) cannot be referenced from a static context
RentShop("Game",cat,ListModel2);
^
MainApp.java:407: error: non-static variable this cannot be referenced from a static context
list3.addMouseListener(this);
^
MainApp.java:414: error: non-static method setBounds(int,int,int,int) cannot be referenced from a static context
setBounds(300, 300, 350, 150);
^
MainApp.java:416: error: non-static method getContentPane() cannot be referenced from a static context
Container cp3 = getContentPane();
^
MainApp.java:426: error: non-static variable this cannot be referenced from a static context
button3.addActionListener(this);
^
MainApp.java:447: error: non-static method pack() cannot be referenced from a static context
pack();
^
MainApp.java:449: error: non-static method setDefaultCloseOperation(int) cannot be referenced from a static context
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
^
MainApp.java:463: error: non-static method add(Component) cannot be referenced from a static context
add(tabbedPane);
^
Note: MainApp.java uses unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.
21 errorsI know about the error in general, however I think this is a different case. For example, I use "this" in "addMouseListener", in a static function called in a static main, but I still get an error.
My code of MainApp.java, the main class, is:
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.File;
import javax.swing.JButton;
import javax.swing.JDialog;
import javax.swing.JFileChooser;
import javax.swing.JFrame;
import java.awt.BorderLayout;
import javax.swing.DefaultListModel;
import javax.swing.JTabbedPane;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JButton;
import javax.swing.JList;
import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
import java.util.*;
public class MainApp extends JFrame implements ActionListener, MouseListener
{
private static String ans;
private static int ans2;
private static boolean over;
private int li=-1;
private int li2=-1;
private int li3=-1;
private static JFrame frame;
private static JButton button1;
private static JButton button2;
private static JButton button3;
private static JButton gfbutton;
private static JButton rbutton;
private static JLabel label;
private static JLabel label2;
private static JLabel label3;
private static JTextArea area;
private static JTextArea area2;
private static JTextArea area3;
private static JList list;
private static JList list2;
private static JList list3;
private static DefaultListModel ListModel;
private static DefaultListModel ListModel2;
private static DefaultListModel ListModel3;
public static Catalogs cat = new Catalogs();
public static String Items;
public static String RentsList;
public void lists(JTextArea area, JLabel label, JList list) //For games and films
{
boolean flag=false;
int i=0;
while(i<cat.items.size() && flag==false)
{
if( cat.items.get(i).getProname().equals ( list.getSelectedValue() ) )
{
area.setText(cat.items.get(i).toString());
String pathimage = "Images/" + cat.items.get(i).getProname() + ".jpg";
label.setIcon(new ImageIcon(pathimage));
flag=true;
}
i++;
}
if(cat.items.get(i).getRentnum()>0)
cat.rentItems.add(cat.items.get(i).RentItem());
else
JOptionPane.showMessageDialog(null,"Sorry...","There are no available copies left",JOptionPane.INFORMATION_MESSAGE);
}
public void mouseClicked(MouseEvent event)
{
if (list.getSelectedIndex() != li)
{
lists(area, label, list);
}
else if (list2.getSelectedIndex() != li2)
{
lists(area2, label2, list2);
}
else if (list3.getSelectedIndex() != li3)
{
boolean flag=false;
int i=0;
while(i<cat.rentItems.size() && flag==false)
{
if( cat.rentItems.get(i).getProname().equals ( list.getSelectedValue() ) )
{
area.setText(cat.rentItems.get(i).toString());
String pathimage = "Images/" + cat.rentItems.get(i).getProname() + ".jpg";
label.setIcon(new ImageIcon(pathimage));
flag=true;
}
i++;
}
}
li = list.getSelectedIndex();
li2 = list2.getSelectedIndex();
li3 = list3.getSelectedIndex();
}
public void mouseExited(MouseEvent event){}
public void mouseEntered(MouseEvent event){}
public void mouseReleased(MouseEvent event){}
public void mousePressed(MouseEvent event){}
public void actionPerformed(ActionEvent e)
{
if (e.getSource() == button1) {
cat.items.get(list.getSelectedIndex()).RentItem();
}
else if (e.getSource() == button2) {
cat.items.get(list2.getSelectedIndex()).RentItem();
}
else if (e.getSource() == button3)
{
boolean flag=false;
int i = list3.getSelectedIndex();
if (i != -1)
{
while(i<cat.items.size() && flag==false) //Find the product in items via renting name
{
if( cat.items.get(i).getProname().equals( cat.rentItems.get(i).getProname() ) )
{
cat.items.get(i).setRentnum( cat.items.get(i).getRentnum() + 1 );
flag=true;
}
i++;
}
ListModel3.remove(i);
cat.rentItems.remove(i);
}
}
}
public void RentShop(String type, Catalogs cat, DefaultListModel ListModel) //Function for renting each product
{
for(Products product : cat.items)
{
if ( product.getType().equals(type) )
ListModel.addElement( product.getProname() );
}
}
//--------------------------------------------------Main program
public static void main(String args[])
{
//First window for importing
JFrame.setDefaultLookAndFeelDecorated(true);
JDialog.setDefaultLookAndFeelDecorated(true);
frame = new JFrame("Importing...");
frame.setLayout(new FlowLayout());
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JButton gfbutton = new JButton("Select File for Games and Films");
JButton rbutton = new JButton("Select File for Rents");
gfbutton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent ae) {
JFileChooser fi = new JFileChooser();
int returnValue = fi.showOpenDialog(null);
if (returnValue == fi.APPROVE_OPTION) {
Items = fi.getSelectedFile().getPath();
}
if(over==true) frame.dispose();
over = true;
}
});
rbutton.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent ae)
{
JFileChooser fi = new JFileChooser();
int returnValue = fi.showOpenDialog(null);
if (returnValue == fi.APPROVE_OPTION) {
RentsList = fi.getSelectedFile().getPath();
////////////////////??????????
}
if(over==true)
{
frame.dispose();
MainPro();
}
over = true;
}
});
}
public static void MainPro(){
frame = new JFrame("Video Club"); //?
frame.setBounds(500,300,400,500);
frame.add(gfbutton);
frame.add(rbutton);
frame.pack();
frame.setVisible(true);
L_File lf = new L_File(cat,"Items.txt", "RentsList.txt"); //Importing
lf.loadFile();
//Main window, 1st tab
JTabbedPane tabbedPane = new JTabbedPane();
JPanel panel1 = new JPanel();
tabbedPane.addTab("Movies",null,panel1,"Movies");
JList list = new JList();
list.addMouseListener(this);
panel1.add(list);
JTextArea area = new JTextArea("Details");
panel1.add(area,BorderLayout.SOUTH);
ListModel = new DefaultListModel();
setBounds(300, 300, 350, 150);
Container cp = getContentPane();
cp.setLayout(new BorderLayout());
panel1.setLayout(new FlowLayout());
button1= new JButton("Rent");
button1.addActionListener(this);
panel1.add(button1);
area.setFont(new Font("Serif", Font.ITALIC, 18));
area.setForeground(Color.BLUE);
area.setEditable(false);
cp.add(panel1, BorderLayout.LINE_START);
// A JList presents the user with a group of items (DefaultListModel)
list = new JList(ListModel);
list.setSelectedIndex(0);
// A JScrollPane provides a scrollable view of a component
JScrollPane listScroller = new JScrollPane(list);
listScroller.setPreferredSize(new Dimension(150, 100));
cp.add(listScroller, BorderLayout.CENTER);
label = new JLabel();
//label.setIcon(new ImageIcon(products.get(0).getImagePath()));
cp.add(label, BorderLayout.LINE_END);
pack();
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
RentShop("Film",cat,ListModel);
//2nd tab
JPanel panel2 = new JPanel();
tabbedPane.addTab("Games",null,panel2,"Games");
JList list2 = new JList();
list2.addMouseListener(this);
panel2.add(list2,BorderLayout.SOUTH);
JTextArea area2 = new JTextArea("Details");
panel2.add(area2);
DefaultListModel ListModel2 = new DefaultListModel();
setBounds(300, 300, 350, 150);
Container cp2 = getContentPane();
cp2.setLayout(new BorderLayout());
panel2.setLayout(new FlowLayout());
button2= new JButton("Rent");
panel2.add(button2);
button2.addActionListener(this);
area2.setFont(new Font("Serif", Font.ITALIC, 18));
area2.setForeground(Color.BLUE);
area2.setEditable(false);
cp2.add(panel2, BorderLayout.LINE_START);
// A JList presents the user with a group of items (DefaultListModel)
list2 = new JList(ListModel);
list2.setSelectedIndex(0);
// A JScrollPane provides a scrollable view of a component
JScrollPane listScroller2 = new JScrollPane(list);
listScroller2.setPreferredSize(new Dimension(150, 100));
cp2.add(listScroller2, BorderLayout.CENTER);
label2 = new JLabel();
//label2.setIcon(new ImageIcon(products.get(0).getImagePath()));
cp2.add(label2, BorderLayout.LINE_END);
pack();
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
RentShop("Game",cat,ListModel2);
//3rd tab
JPanel panel3 = new JPanel();
tabbedPane.addTab("Rents",null,panel3,"Rents");
JList list3 = new JList();
list3.addMouseListener(this);
panel3.add(list3,BorderLayout.SOUTH);
JTextArea area3 = new JTextArea("Details");
panel3.add(area3);
DefaultListModel ListModel3 = new DefaultListModel();
setBounds(300, 300, 350, 150);
Container cp3 = getContentPane();
cp3.setLayout(new BorderLayout());
panel3.setLayout(new FlowLayout());
button3= new JButton("Remove Rent");
panel3.add(button3);
button3.addActionListener(this);
area3.setFont(new Font("Serif", Font.ITALIC, 18));
area3.setForeground(Color.BLUE);
area3.setEditable(false);
cp3.add(panel3, BorderLayout.LINE_START);
// A JList presents the user with a group of items (DefaultListModel)
list3 = new JList(ListModel2);
list3.setSelectedIndex(0);
// A JScrollPane provides a scrollable view of a component
JScrollPane listScroller3 = new JScrollPane(list);
listScroller3.setPreferredSize(new Dimension(150, 100));
cp3.add(listScroller3, BorderLayout.CENTER);
pack();
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
//After designing:
for(Rents rent : cat.rentItems)
{
ListModel3.addElement( rent.getProname() );
}
JOptionPane.showMessageDialog(null,"Total Cost","The total renting cost is " + cat.CalculateTotalCost() + " drachmes",JOptionPane.PLAIN_MESSAGE);
add(tabbedPane);
}
}Any idea will be much appreciated, thank you!
You need to create an instance of MainApp in main
Instead of having all your code in your main(), you need to transfer that code to a new private void run() method (or whatever you want to call it).
public static void main(String[] args) {
new MainApp().run();
}
Now, since you have an instance get rid of all your private static variables in favor of just private
private static String ans;
becomes
private String ans;
etc
Something like... (I have not tested this). Note, I changed MainPro to an instance method as well. Removed all the statics
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.File;
import javax.swing.JButton;
import javax.swing.JDialog;
import javax.swing.JFileChooser;
import javax.swing.JFrame;
import java.awt.BorderLayout;
import javax.swing.DefaultListModel;
import javax.swing.JTabbedPane;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JButton;
import javax.swing.JList;
import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
import java.util.*;
public class MainApp extends JFrame implements ActionListener, MouseListener
{
private String ans;
private int ans2;
private boolean over;
private int li=-1;
private int li2=-1;
private int li3=-1;
private JFrame frame;
private JButton button1;
private JButton button2;
private JButton button3;
private JButton gfbutton;
private JButton rbutton;
private JLabel label;
private JLabel label2;
private JLabel label3;
private JTextArea area;
private JTextArea area2;
private JTextArea area3;
private JList list;
private JList list2;
private JList list3;
private DefaultListModel ListModel;
private DefaultListModel ListModel2;
private DefaultListModel ListModel3;
public static Catalogs cat = new Catalogs();
public static String Items;
public static String RentsList;
public void lists(JTextArea area, JLabel label, JList list) //For games and films
{
boolean flag=false;
int i=0;
while(i<cat.items.size() && flag==false)
{
if( cat.items.get(i).getProname().equals ( list.getSelectedValue() ) )
{
area.setText(cat.items.get(i).toString());
String pathimage = "Images/" + cat.items.get(i).getProname() + ".jpg";
label.setIcon(new ImageIcon(pathimage));
flag=true;
}
i++;
}
if(cat.items.get(i).getRentnum()>0)
cat.rentItems.add(cat.items.get(i).RentItem());
else
JOptionPane.showMessageDialog(null,"Sorry...","There are no available copies left",JOptionPane.INFORMATION_MESSAGE);
}
public void mouseClicked(MouseEvent event)
{
if (list.getSelectedIndex() != li)
{
lists(area, label, list);
}
else if (list2.getSelectedIndex() != li2)
{
lists(area2, label2, list2);
}
else if (list3.getSelectedIndex() != li3)
{
boolean flag=false;
int i=0;
while(i<cat.rentItems.size() && flag==false)
{
if( cat.rentItems.get(i).getProname().equals ( list.getSelectedValue() ) )
{
area.setText(cat.rentItems.get(i).toString());
String pathimage = "Images/" + cat.rentItems.get(i).getProname() + ".jpg";
label.setIcon(new ImageIcon(pathimage));
flag=true;
}
i++;
}
}
li = list.getSelectedIndex();
li2 = list2.getSelectedIndex();
li3 = list3.getSelectedIndex();
}
public void mouseExited(MouseEvent event){}
public void mouseEntered(MouseEvent event){}
public void mouseReleased(MouseEvent event){}
public void mousePressed(MouseEvent event){}
public void actionPerformed(ActionEvent e)
{
if (e.getSource() == button1) {
cat.items.get(list.getSelectedIndex()).RentItem();
}
else if (e.getSource() == button2) {
cat.items.get(list2.getSelectedIndex()).RentItem();
}
else if (e.getSource() == button3)
{
boolean flag=false;
int i = list3.getSelectedIndex();
if (i != -1)
{
while(i<cat.items.size() && flag==false) //Find the product in items via renting name
{
if( cat.items.get(i).getProname().equals( cat.rentItems.get(i).getProname() ) )
{
cat.items.get(i).setRentnum( cat.items.get(i).getRentnum() + 1 );
flag=true;
}
i++;
}
ListModel3.remove(i);
cat.rentItems.remove(i);
}
}
}
public void RentShop(String type, Catalogs cat, DefaultListModel ListModel) //Function for renting each product
{
for(Products product : cat.items)
{
if ( product.getType().equals(type) )
ListModel.addElement( product.getProname() );
}
}
private void run() {
//First window for importing
JFrame.setDefaultLookAndFeelDecorated(true);
JDialog.setDefaultLookAndFeelDecorated(true);
frame = new JFrame("Importing...");
frame.setLayout(new FlowLayout());
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JButton gfbutton = new JButton("Select File for Games and Films");
JButton rbutton = new JButton("Select File for Rents");
gfbutton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent ae) {
JFileChooser fi = new JFileChooser();
int returnValue = fi.showOpenDialog(null);
if (returnValue == fi.APPROVE_OPTION) {
Items = fi.getSelectedFile().getPath();
}
if(over==true) frame.dispose();
over = true;
}
});
rbutton.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent ae)
{
JFileChooser fi = new JFileChooser();
int returnValue = fi.showOpenDialog(null);
if (returnValue == fi.APPROVE_OPTION) {
RentsList = fi.getSelectedFile().getPath();
////////////////////??????????
}
if(over==true)
{
frame.dispose();
MainPro();
}
over = true;
}
});
}
//--------------------------------------------------Main program
public static void main(String args[])
{
new MainApp().run();
}
/**
* I have no idea what you're doing here but this should also not be static
*/
private void MainPro(){
frame = new JFrame("Video Club"); //?
frame.setBounds(500,300,400,500);
frame.add(gfbutton);
frame.add(rbutton);
frame.pack();
frame.setVisible(true);
L_File lf = new L_File(cat,"Items.txt", "RentsList.txt"); //Importing
lf.loadFile();
//Main window, 1st tab
JTabbedPane tabbedPane = new JTabbedPane();
JPanel panel1 = new JPanel();
tabbedPane.addTab("Movies",null,panel1,"Movies");
JList list = new JList();
list.addMouseListener(this);
panel1.add(list);
JTextArea area = new JTextArea("Details");
panel1.add(area,BorderLayout.SOUTH);
ListModel = new DefaultListModel();
setBounds(300, 300, 350, 150);
Container cp = getContentPane();
cp.setLayout(new BorderLayout());
panel1.setLayout(new FlowLayout());
button1= new JButton("Rent");
button1.addActionListener(this);
panel1.add(button1);
area.setFont(new Font("Serif", Font.ITALIC, 18));
area.setForeground(Color.BLUE);
area.setEditable(false);
cp.add(panel1, BorderLayout.LINE_START);
// A JList presents the user with a group of items (DefaultListModel)
list = new JList(ListModel);
list.setSelectedIndex(0);
// A JScrollPane provides a scrollable view of a component
JScrollPane listScroller = new JScrollPane(list);
listScroller.setPreferredSize(new Dimension(150, 100));
cp.add(listScroller, BorderLayout.CENTER);
label = new JLabel();
//label.setIcon(new ImageIcon(products.get(0).getImagePath()));
cp.add(label, BorderLayout.LINE_END);
pack();
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
RentShop("Film",cat,ListModel);
//2nd tab
JPanel panel2 = new JPanel();
tabbedPane.addTab("Games",null,panel2,"Games");
JList list2 = new JList();
list2.addMouseListener(this);
panel2.add(list2,BorderLayout.SOUTH);
JTextArea area2 = new JTextArea("Details");
panel2.add(area2);
DefaultListModel ListModel2 = new DefaultListModel();
setBounds(300, 300, 350, 150);
Container cp2 = getContentPane();
cp2.setLayout(new BorderLayout());
panel2.setLayout(new FlowLayout());
button2= new JButton("Rent");
panel2.add(button2);
button2.addActionListener(this);
area2.setFont(new Font("Serif", Font.ITALIC, 18));
area2.setForeground(Color.BLUE);
area2.setEditable(false);
cp2.add(panel2, BorderLayout.LINE_START);
// A JList presents the user with a group of items (DefaultListModel)
list2 = new JList(ListModel);
list2.setSelectedIndex(0);
// A JScrollPane provides a scrollable view of a component
JScrollPane listScroller2 = new JScrollPane(list);
listScroller2.setPreferredSize(new Dimension(150, 100));
cp2.add(listScroller2, BorderLayout.CENTER);
label2 = new JLabel();
//label2.setIcon(new ImageIcon(products.get(0).getImagePath()));
cp2.add(label2, BorderLayout.LINE_END);
pack();
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
RentShop("Game",cat,ListModel2);
//3rd tab
JPanel panel3 = new JPanel();
tabbedPane.addTab("Rents",null,panel3,"Rents");
JList list3 = new JList();
list3.addMouseListener(this);
panel3.add(list3,BorderLayout.SOUTH);
JTextArea area3 = new JTextArea("Details");
panel3.add(area3);
DefaultListModel ListModel3 = new DefaultListModel();
setBounds(300, 300, 350, 150);
Container cp3 = getContentPane();
cp3.setLayout(new BorderLayout());
panel3.setLayout(new FlowLayout());
button3= new JButton("Remove Rent");
panel3.add(button3);
button3.addActionListener(this);
area3.setFont(new Font("Serif", Font.ITALIC, 18));
area3.setForeground(Color.BLUE);
area3.setEditable(false);
cp3.add(panel3, BorderLayout.LINE_START);
// A JList presents the user with a group of items (DefaultListModel)
list3 = new JList(ListModel2);
list3.setSelectedIndex(0);
// A JScrollPane provides a scrollable view of a component
JScrollPane listScroller3 = new JScrollPane(list);
listScroller3.setPreferredSize(new Dimension(150, 100));
cp3.add(listScroller3, BorderLayout.CENTER);
pack();
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
//After designing:
for(Rents rent : cat.rentItems)
{
ListModel3.addElement( rent.getProname() );
}
JOptionPane.showMessageDialog(null,"Total Cost","The total renting cost is " + cat.CalculateTotalCost() + " drachmes",JOptionPane.PLAIN_MESSAGE);
add(tabbedPane);
}
}