Static variable error

I know that non-static variables cannot be refrenced from a static context and I see where this error is happening but I can't figure out why. It doesn't appear that I am cross referencing static and non-static variables.
import javax.swing.*;
import java.awt.event.*;
import java.awt.*;
import java.util.*;
public class CookieStuff extends JFrame implements ActionListener
     private final int XSIZE = 600;
     private final int YSIZE = 300;
     private JButton myButton;
     private JButton myButton2;
     private JLabel myLabel;
     private JLabel myLabel2;
     public JTextField myTextField;
      * Constructor
     public CookieStuff(String title)
          super(title);
          setSize(XSIZE,YSIZE);
          myButton = new JButton("Bake cookies");
          myButton2= new JButton("Eat cookies");
          myLabel = new JLabel("Number of cookies left: ");
          myLabel2= new JLabel("Enter # of cookies and select a button");
          myTextField = new JTextField(5);
          myButton.addActionListener(this);
          myButton2.addActionListener(this);
          add(myButton,BorderLayout.NORTH);
          add(myButton2,BorderLayout.SOUTH);
          add(myLabel,BorderLayout.WEST);
          add(myLabel2,BorderLayout.EAST);
          add(myTextField,BorderLayout.CENTER);
     public static void welcomeStuff()
          JOptionPane.showMessageDialog(null,"Welcome to grandma's cookie jar..");
     public void actionPerformed(ActionEvent ev)
         Object source = ev.getSource();
         if(source == myButton)
               if(CookieJar.bake() > CookieJar.COOKIES_ALLOWED)
                    JOptionPane.showMessageDialog(this, "Grandma's jar is too small for that many cookies");
               else
                    JOptionPane.showMessageDialog(this, CookieJar.bake());
                    myLabel.setText("Number of cookies left: " + (CookieJar.bake()));
          else
               if(CookieJar.eat() < 0)
                    JOptionPane.showMessageDialog(this, "There are not enough cookies in the jar fatso");
               else
                    JOptionPane.showMessageDialog(this, CookieJar.eat());
import javax.swing.*;
import java.awt.event.*;
import java.awt.*;
import java.util.*;
public class CookieJar
    public static final int COOKIES_ALLOWED = 40;
    public int numOfCookies;
    public int cookieCount;
    public CookieJar()
          cookieCount = numOfCookies;
          numOfCookies++;
     public int eat()
          int numOfCookies = 0;
          numOfCookies = (numOfCookies - Integer.parseInt(CookieStuff.myTextField.getText()));
          return numOfCookies;
     public int bake()
          int numOfCookies = 0;
          numOfCookies = (numOfCookies + Integer.parseInt(CookieStuff.myTextField.getText()));
          return numOfCookies;
}The last 2 methods eat( ) and bake( ) are giving the errors. Thanks.

C:\Documents and Settings\Travis Mandrell\Desktop\DePaul\CSC212\hw8\CookieStuff.java:49: non-static method bake() cannot be referenced from a static context
               if(CookieJar.bake() > CookieJar.COOKIES_ALLOWED)
^
C:\Documents and Settings\Travis Mandrell\Desktop\DePaul\CSC212\hw8\CookieStuff.java:55: non-static method bake() cannot be referenced from a static context
                    JOptionPane.showMessageDialog(this, CookieJar.bake());
^
C:\Documents and Settings\Travis Mandrell\Desktop\DePaul\CSC212\hw8\CookieStuff.java:56: non-static method bake() cannot be referenced from a static context
                    myLabel.setText("Number of cookies left: " + (CookieJar.bake()));
^
C:\Documents and Settings\Travis Mandrell\Desktop\DePaul\CSC212\hw8\CookieStuff.java:62: non-static method eat() cannot be referenced from a static context
               if(CookieJar.eat() < 0)
^
C:\Documents and Settings\Travis Mandrell\Desktop\DePaul\CSC212\hw8\CookieStuff.java:68: non-static method eat() cannot be referenced from a static context
JOptionPane.showMessageDialog(this, CookieJar.eat());
^
.\CookieJar.java:21: non-static variable myTextField cannot be referenced from a static context
          numOfCookies = (numOfCookies - Integer.parseInt(CookieStuff.myTextField.getText()));
^
.\CookieJar.java:28: non-static variable myTextField cannot be referenced from a static context
          numOfCookies = (numOfCookies + Integer.parseInt(CookieStuff.myTextField.getText()));
^
7 errors

Similar Messages

Non static variable error

There may be more errors in here besides the static variable error. I made the methods static for the method call in my constructor Product(name, price). The purpose of this Class is to the the name and price of a product from user input, subtract 5.00 from the price, and return the new price. Please help!!!
public class Product
public Product(String name, double price)
String product;
price = Product.getPrice(price);
Double.toString(price);
//this.product = product;
product = Product.getName(name) + Product.getPrice(price);
public static String getName(String name)
System.out.println("What is their name?: ");
name = in.nextLine(); // I GET A NONSTATIC VARIABLE ERROR FOR variable "in" HERE.
return name;
public static double getPrice(double price)
this.price = price;
System.out.println("What is the price?: ");
price = in.nextDouble();
return price;
public double reducePrice()
price = price - 5.00;
return price;
public String getProduct()
product = new Product(name, price);
return product;
Scanner in = new Scanner(System.in);
public static String name;
//public double price;
}

you not define the class member properly.
the class member is define before the constructor as
public class Product {
     static Scanner in = new Scanner(System.in);
     String product;
     double price;
     public static String name;
     public Product(String name, double price) {
          price = Product.getPrice(price);
          Double.toString(price);
          // this.product = product;
          product = Product.getName(name) + Product.getPrice(price);
}

Non static variable errors

I have been working on this file for 4 days now and I can't get past these errors.
Here's the whole project:
package toysmanager;
public class ToysManager {
//Method ToysManager
public ToysManager() {
//Method main
public static void main(String[] args) {
ToddlerToy Train1 = new ToddlerToy();
ToddlerToy Train2 = new ToddlerToy();
ToddlerToy Train3 = new ToddlerToy();
System.out.print("This is an object of type ToysManager");
Train1.PrintProductID();
Train2.PrintProductID();
Train3.PrintProductID();
public class ToddlerToy{
private int ProductID = 0;
private String ProductName = "";
private float ProductPrice = 0;
public ToddlerToy(int id,String name, float price){
ProductID = id;
ProductName = name;
ProductPrice = price;
//Method PrintProductID
public int PrintProductID(){
System.out.print("This method is PrintProductID in the class ToddlerToy");
System.out.print("Product ID is:" + ProductID);
return ProductID;
public String PrintProductName(){
System.out.print("This method is PrintProductName in the class ToddlerToy");
System.out.print("Product Name:" + ProductName);
return ProductName;
public float PrintProductPrice(){
System.out.print("This method is PrintProductPrice in the class ToddlerToy");
System.out.print("Product Price: $" + ProductPrice);
return ProductPrice;
And here are the errors:
"ToysManager.java": non-static variable this cannot be referenced from a static context at line 9, column 29
"ToysManager.java": ToddlerToy(int,java.lang.String,float) in toysmanager.ToysManager.ToddlerToy cannot be applied to () at line 9, column 29
"ToysManager.java": non-static variable this cannot be referenced from a static context at line 10, column 29
"ToysManager.java": ToddlerToy(int,java.lang.String,float) in toysmanager.ToysManager.ToddlerToy cannot be applied to () at line 10, column 29
"ToysManager.java": non-static variable this cannot be referenced from a static context at line 11, column 29
"ToysManager.java": ToddlerToy(int,java.lang.String,float) in toysmanager.ToysManager.ToddlerToy cannot be applied to () at line 11, column 29
Any help would be appreciated as I am plainly not understanding this even with a book.

Annie:
Could you help me understand the original ToyManager instructions more please? Not asking you to do the work for me I just do not understand exactly what they want me to do...
Assignment:
After you install JCreator, write a Java program, with a single class called ToysManager. The main method should print the name of the class, for example: "This is an object of type ToysManager."
(Hint: the process is very similar to the "Hello World!" program.)
Please add file (.java)
Group Portion:
Deliverables: two *.java files
As a group, add a second class called ToddlerToy to your ToysManager project.
Here are the requirements for the ToddlerToy:
    * The class ToddlerToy is public and has a default constructor.
    * It has one private attribute called ProductID (of type int).
    * It has two public methods called SetProductId() and PrintProductId().
    * The method SetProductId() assigns a value to the attribute ProductId. For now, the value is hard-coded.
    * The method PrintProductId prints the value of the attribute ProductId.
    * The class ToddlerToy has no main() method. In Java, there is only one main method for the entire program. In this case, the main method is in the ToysManager class.
Here are the requirements for the main method of the ToysManager class:
    * Create an object called Train1 of class type ToddlerToy, using the default constructor.
    * Call the methods SetProductId() and PrintProductId() to set then print the the value of ProductId.
    * The first statement in each method should print the name of the method, for example: "This is method <method name> in class <class name>". This should help you trace the execution of your program. Feel free to comment out the print statement.
    * On the Small Group Discussion Board, discuss your understanding of the concepts of class, object, constructor, method, and attribute.
    * Give one example of a class (giving its name, attributes, and methods) that could be part of the shipping application.ANY help with this at all is greatly appreciated...a friend of mine found your post and used it to give me code snippets for help and I had no idea. Nearly got me in deep water...redoing the assignment but personally I find the next two assignments much easier to understand than this one. The instructions are confusing to me...can you point me in the right direction?

Static variable error in main function

Dont know why it would be doing this. It is bascially telling me that every class I call in my main function needs to be static which is crazy.
import javax.swing.*;
import java.awt.*;
class Frame extends JFrame
     public Frame()
          setTitle("My Empty Frame");
          setSize(300,200);
          setLocation(10,200);
          this.show();
public class Main extends JFrame
     public JFrame frame;
     public Main()
          frame = new JFrame();
     public static void main(String[] args)
          System.out.println("CS348 Project 1");
          frame.setVisible(true); <--------------------ERROR
}Thanks for the help.

The problem (basically), is that you could do the following if you felt like it:
import javax.swing.*;
import java.awt.*;
class Frame extends JFrame
     public Frame()
          setTitle("My Empty Frame");
          setSize(300,200);
          setLocation(10,200);
          this.show();
public class Main extends JFrame
     public JFrame frame;
     public Main()
          frame = new JFrame();
     public static void main(String[] args)
          Main main1 = new Main();
          Main main2 = new Main();
          Main main3 = new Main();
          //what frame is this talking about??
          frame.setVisible(true); <--------------------ERROR
}What you would want instead is probably something like this:
Main main1 = new Main();
main1.getFrame().setVisible(true);This leads to a few other questions: why are you extending JFrame if you have a JFrame variable in the class? Does that class have a JFrame, or is it a JFrame? You should almost definitely go with the "have" answer.

Error on compile - non-static variable can not be referencedfrom static con

Error on compile happening with addButton?
Thanks
import java.awt.*;
import java.awt.event.*;
import javax.swing.JButton;
import javax.swing.JLabel;
import javax.swing.JTextField;
import javax.swing.JFrame;
public class Log implements ActionListener {
JButton addButton;
public static void addComponentsToPane(Container pane) {
pane.setLayout(new GridBagLayout());
GridBagConstraints c = new GridBagConstraints();
     c.gridy = 3;
c.gridx = 0;
     JLabel callsignLabel= new JLabel("Callsign");
pane.add(callsignLabel, c);
     c.gridy = 3;
c.gridx = 1;
     JLabel nameLabel= new JLabel("Name");
pane.add(nameLabel, c);
     c.gridy = 3;
c.gridx = 2;
     JLabel timeLabel= new JLabel("Time");
pane.add(timeLabel, c);
     c.gridy = 3;
c.gridx = 3;
     JLabel dateLabel= new JLabel("Date");
pane.add(dateLabel, c);
     c.gridy = 3;
c.gridx = 4;
     JLabel frequencyLabel= new JLabel("Freq ");
pane.add(frequencyLabel, c);
     c.gridy = 3;
c.gridx = 5;
     JLabel locationLabel = new JLabel("Country/State");
pane.add(locationLabel, c);
c.gridy = 5;
c.gridx = 0;
     addButton = new JButton("Add");
pane.add(addButton, c);
     addButton.addActionListener(this);

Thank you for the reply
I am new to Java
What is wrong with the way it is coded?The error message tells you what's wrong: You're trying to reference a non-static variable from a static context.
If you don't know what that means, then click the link I provided and look at the results from that google search. You might have to go through a few before you find a satisfactory explanation. And after you've done that, if you have specific questions about things you didn't understand there, please post again.

Runtime error in linking with static variables....

Hi,
I am building a shared library which includes a compiled object generated from a class containing the static variables only and also I have another version of same class with same & some new static variables in it and using that to generate another shared library. Now when I tried to run a program
which links with both the library it core dumps when it tries to return from the program i.e when it finishes.
Can someone please help me explain why my program is behaving like that?? Can duplicate inculsion of static variables in different scope can cause problem ?? How can this be avoided ?
Also please be advised that the class with static variables gets generated at the compile time using a script which uses a DTD whose version (specification) can be different in both the libraries therefore I can't just seperate the common stuff into one class and specific into another.
Thanks.
Rajeev.

Not to worry...found the answer in another post. Seems like patches need to applied to the OS.

Using a static variable declared in an applet in another class

Hi guys,
I created an applet and i want to use one of the static variables declared in teh applet class in another class i have. however i get an error when i try to do that...
in my Return2 class i try to call the variable infoPanel (declared as a static JPanel in myApplet...myApplet is set up like so:
public class myApplet extends JApplet implements ActionListener, ListSelectionListener
here are some of the lines causing a problem in the Return2 class:
myApplet.infoPanel.removeAll();
myApplet.infoPanel.add(functionForm2.smgframeold);
myApplet.infoPanel.validate();
myApplet.infoPanel.repaint();
here are some of the errors i get
dummy/Return2.java [211:1] package myApplet does not exist
myApplet.infoPanel.removeAll();
^
dummy/Return2.java [212:1] package myApplet does not exist
myApplet.infoPanel.add(functionForm2.smgframeold);
^
dummy/Return2.java [213:1] package myApplet does not exist
myApplet.infoPanel.validate();
^
dummy/Return2.java [214:1] package myApplet does not exist
myApplet.infoPanel.repaint();
^
please help! thanks :)

I don't declare any packages though....i think it just doesn't recognize myApplet for some reason..
other errors i got compiling are:
dummy/Return2.java [82:1] cannot resolve symbol
symbol : variable myApplet
location: class Return2
updateDesc.setString(3, myApplet.staticName);
I Don't get why i'm getting this error cuase they worked fine when myApplet was a standalone application, not an applet.
myApplet is in the same folder as Return2 and it compiles properly.

Non-static variable Help needed

Hi, I am creating a multi threaded web server but get the following error
non-static variable this cannot be referenced from a static context
HttpRequest request = new HttpRequest(connectionSocket);
Please could someone help.
Many Thanks
import java.io.* ;
import java.net.* ;
import java.util.* ;
public final class MultiWebServer
public static void main(String argv[]) throws Exception
     // Set the port number.
     int port = 6789;
// Establish the listen socket.
               String fileName;
               ServerSocket listenSocket = new ServerSocket(port);
// Process HTTP service requests in an infinite loop.
while (true) {
     // Listen for a TCP connection request.
     Socket connectionSocket = listenSocket.accept();
// Construct an object to process the HTTP request message.
HttpRequest request = new HttpRequest(connectionSocket);
// Create a new thread to process the request.
Thread thread = new Thread(request);
// Start the thread.
thread.start();
final class HttpRequest implements Runnable
     final static String CRLF = "\r\n";
     Socket socket;
String requestMessageLine;
String fileName;
Date todaysDate;
     // Constructor
     public HttpRequest(Socket socket) throws Exception
          this.socket = socket;
          socket = null;
// Implement the run() method of the Runnable interface.
public void run()
     try {
          processRequest();
     } catch (Exception e) {
          System.out.println(e);
private void processRequest() throws Exception
     // Get a reference to the socket's input and output streams.
     //InputStream is = new InputStream(socket.getInputStream());
     //DataOutputStream os = new DataOutputStream(socket.getOutputStream());
BufferedReader inFromClient =
                    new BufferedReader(new InputStreamReader(
                         socket.getInputStream()));
               DataOutputStream outToClient =
                    new DataOutputStream(
                         socket.getOutputStream());
     // Set up input stream filters.
     requestMessageLine = inFromClient.readLine();
     //BufferedReader br = null;
     // Get the request line of the HTTP request message.
String requestLine = null;
// Display the request line.
System.out.println();
System.out.println(requestLine);
StringTokenizer tokenizedLine =
                         new StringTokenizer(requestMessageLine);
               if (tokenizedLine.nextToken().equals("GET"))
                    fileName = tokenizedLine.nextToken();
                    if ( fileName.startsWith("/")==true )
                         fileName = fileName.substring(1);
File file = new File(fileName);
                    int numOfBytes = (int)file.length();
                    FileInputStream inFile = new FileInputStream(fileName);
                    byte[] fileInBytes = new byte[numOfBytes];
                    inFile.read(fileInBytes);
                    /* Send the HTTP header */
                    outToClient.writeBytes("HTTP/1.1 200 Document Follows\r\n");
                    if (fileName.endsWith(".jpg"))
                         outToClient.writeBytes("Content-Type: image/jpeg\r\n");
                    if (fileName.endsWith(".jpeg"))
                         outToClient.writeBytes("Content-Type: image/jpeg\r\n");
                    if (fileName.endsWith(".gif"))
                         outToClient.writeBytes("Content-Type: image/gif\r\n");
                    if (fileName.endsWith(".html"))
                         outToClient.writeBytes("Content-Type: text/html\r\n");
                    if (fileName.endsWith(".htm"))
                         outToClient.writeBytes("Content-Type: text/html\r\n");
                    outToClient.writeBytes("Content-Length: " + numOfBytes + "\r\n");
                    outToClient.writeBytes("\r\n");
                    /* Now send the actual data */
                    outToClient.write(fileInBytes, 0, numOfBytes);
                    socket.close();
               else
               System.out.println("Bad Request Message");
               todaysDate = new Date();
               try {
                    FileInputStream inlog = new FileInputStream("log.txt");
                    System.out.println(requestMessageLine + " " + todaysDate );
                    FileOutputStream log = new FileOutputStream("log.txt", true);
                    PrintStream myOutput = new PrintStream(log);
                    myOutput.println("FILE -> " + requestMessageLine + " DATE/TIME -> " + todaysDate);
               catch (IOException e) {
               System.out.println("Error -> " + e);
               System.exit(1);
socket.close();

import java.io.* ;
import java.net.* ;
import java.util.* ;
public final class MultiWebServer
public MultiWebServer(){
try{
// Set the port number.
int port=6789;
// Establish the listen socket.
String fileName;
ServerSocket listenSocket=new ServerSocket(port);
// Process HTTP service requests in an infinite loop.
while(true){
// Listen for a TCP connection request.
Socket connectionSocket=listenSocket.accept();
// Construct an object to process the HTTP request message.
HttpRequest request=new HttpRequest(connectionSocket);
// Create a new thread to process the request.
Thread thread=new Thread(request);
// Start the thread.
thread.start();
}catch(IOException ioe){
}catch(Exception e){
public static void main(String argv[]) throws Exception
new MultiWebServer();
final class HttpRequest implements Runnable
final static String CRLF = "\r\n";
Socket socket;
String requestMessageLine;
String fileName;
Date todaysDate;
// Constructor
public HttpRequest(Socket socket) throws Exception
this.socket = socket;
socket = null;
// Implement the run() method of the Runnable interface.
public void run()
try {
processRequest();
} catch (Exception e) {
System.out.println(e);
private void processRequest() throws Exception
// Get a reference to the socket's input and output streams.
//InputStream is = new InputStream(socket.getInputStream());
//DataOutputStream os = new DataOutputStream(socket.getOutputStream());
BufferedReader inFromClient =
new BufferedReader(new InputStreamReader(
socket.getInputStream()));
DataOutputStream outToClient =
new DataOutputStream(
socket.getOutputStream());
// Set up input stream filters.
requestMessageLine = inFromClient.readLine();
//BufferedReader br = null;
// Get the request line of the HTTP request message.
String requestLine = null;
// Display the request line.
System.out.println();
System.out.println(requestLine);
StringTokenizer tokenizedLine =
new StringTokenizer(requestMessageLine);
if (tokenizedLine.nextToken().equals("GET"))
fileName = tokenizedLine.nextToken();
if ( fileName.startsWith("/")==true )
fileName = fileName.substring(1);
File file = new File(fileName);
int numOfBytes = (int)file.length();
FileInputStream inFile = new FileInputStream(fileName);
byte[] fileInBytes = new byte[numOfBytes];
inFile.read(fileInBytes);
/* Send the HTTP header */
outToClient.writeBytes("HTTP/1.1 200 Document Follows\r\n");
if (fileName.endsWith(".jpg"))
outToClient.writeBytes("Content-Type: image/jpeg\r\n");
if (fileName.endsWith(".jpeg"))
outToClient.writeBytes("Content-Type: image/jpeg\r\n");
if (fileName.endsWith(".gif"))
outToClient.writeBytes("Content-Type: image/gif\r\n");
if (fileName.endsWith(".html"))
outToClient.writeBytes("Content-Type: text/html\r\n");
if (fileName.endsWith(".htm"))
outToClient.writeBytes("Content-Type: text/html\r\n");
outToClient.writeBytes("Content-Length: " + numOfBytes + "\r\n");
outToClient.writeBytes("\r\n");
/* Now send the actual data */
outToClient.write(fileInBytes, 0, numOfBytes);
socket.close();
else
System.out.println("Bad Request Message");
todaysDate = new Date();
try {
FileInputStream inlog = new FileInputStream("log.txt");
System.out.println(requestMessageLine + " " + todaysDate );
FileOutputStream log = new FileOutputStream("log.txt", true);
PrintStream myOutput = new PrintStream(log);
myOutput.println("FILE -> " + requestMessageLine + " DATE/TIME -> " + todaysDate);
catch (IOException e) {
System.out.println("Error -> " + e);
System.exit(1);
socket.close();

Non-static variable being used in static context

I am currently attempting to write a basic user login system using basic applets. I have two JTextFields named "userText" and "passText".
What i am attempting to do is use the ".getText()" method to get the text out of the JTextField and verifying the string against a string already in a file using the bufferedReader, etc.
However when i try to compare the string in the file with the one in the text field using the following code:
if ((line.compareTo(username)) == 0)
i get the following error...
"non-static variable being used in a static context"
Any ideas?

The static method doesn't know about instances of the class instead you pass the instance to the method:
static public void myMethod(MyClass instance, String var) {
if(instance.line.compareTo(var))
And then the call would be:
MyClass.myMethod(anInstance, userName);

How to give different value to a static variable???

Hi all:
Is there any solution to set different values to a static variable???I had try two ways but all have errors!
1.Way_1
protected String tmp=null;
protected void initSituation(int sayorpress)
if (sayorpress==0)
tmp = "string1";
else if (sayorpress==1)
tmp = "string2";
protected static String RESOURCE_STRING = tmp; <---error
Error:non-static variable tmp cannot be referenced from a static context
2.Way_2
protected void initSituation(int sayorpress)
if (sayorpress==0)
protected static String RESOURCE_STRING = "string1"; <---error
else if (sayorpress==1)
protected static String RESOURCE_STRING = "string2"; <---error
Error:illegal start of expression at
not an expression statement at
Thank you very mich!!!

Try this:
protected static String RESOURCE_STRING = null;
protected void initSituation(int sayorpress)
if (sayorpress==0)
yourClass.RESOURCE_STRING = "string1";
else if (sayorpress==1)
yourClass.RESOURCE_STRING = "string2";
You cannot declare a static variable inside a method. But you can access a static variable thorugh your class.

To use a static variable in another class,but report NullPointerException

when TableMain is running,I run testRecord so that let TableMain add a occur informatin and
happened time in a row in TableMain,but when I run testRecord,java report a NullPointerException and I dont know how to solve this problem,thanks for helping me to check my code;(error report info is in end)
import java.awt.event.*;
import javax.swing.table.*;
import java.io.*;
public class TableMain extends JFrame{
JTable table;
static OwnModel model;
String[] columnHeader={"occur","time"};
class OwnModel extends DefaultTableModel{
public OwnModel(Object[] columnNames,int numRows){
super(columnNames,numRows);
public boolean isCellEditable(int row,int column){
return false;
public TableMain(){
model=new OwnModel(columnHeader,0);
table=new JTable(model);
JScrollPane scroll=new JScrollPane(table);
JButton save=new JButton("save record");
JButton delete=new JButton("delete record");
JPanel buttons=new JPanel();
buttons.add(save);
buttons.add(delete);
JLabel sign=new JLabel("occur record");
Container cp=getContentPane();
cp.add(BorderLayout.NORTH,sign);
cp.add(BorderLayout.CENTER,scroll);
cp.add(BorderLayout.SOUTH,buttons);
this.setSize(300,500);
this.setVisible(true);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
public static void main(String[] args){
new TableMain();
import java.util.Vector;
import java.util.Calendar;
import java.text.SimpleDateFormat;
public class testRecord{
public static void main(String[] args){
SimpleDateFormat simpledf=new SimpleDateFormat("yyyy/MM/dd hh:mm:ss");
String tableName="friends";
Calendar occurtime=Calendar.getInstance();
Vector record=new Vector();
record.add("send 'desc' sql, "+"operated table is :"+tableName);
record.add(simpledf.format(occurtime.getTime()));
System.out.println("model is "+Guide.model);
System.out.println("record is "+record);
Guide.model.addRow(record);
error report:
model is null
record is [send 'desc' sql,operated table is :friends, 2004/05/26 11:39:03]
Exception in thread "main" java.lang.NullPointerException
at testRecord.main(testRecord.java:14)

but I just use this constructor once,never use twice
with same jvm;I thinks my idea is not too very badIt's a public constructor (if I'm looking in the right
place) - it could be called from anywhere. To
intialize a static variable outside the declaration,
use a static initializer:private static String whatever;static {
whatever = "whatever";
}Or simply (in this case):private static String whatever = "whatever";

Static variable in session bean

Can we declare static variable in session bean. If we declare what will happen. Will it create error in compile time or not deployed in server.

From a Java language perspective, nothing stops you from declaring a static variable in a session
bean class. It will compile as long as its syntactically correct.
From an EJB programming model perspective, the use of non-final static variables
is discouraged because it breaks the JVM-transparency that is an important aspect of the
EJB architecture. It should be possible to deploy a single EJB application to a cluster and
have it behave exactly as if it were deployed to only one server instance (albeit with higher
overall throughput/performance). Using non-final static variables breaks this property
because the bean instances in one JVM will see a different value for the static variable
than bean instances in a different JVM.
It also forces you to deal with synchronization
of the shared data, which is a complexity that was carefully avoided in the EJB programming
model by ensuring that each bean instance is single-threaded.
Bottom line is you can have "final static" data members in EJB classes but you should
avoid non-final (mutable) static data.
--ken

Non-static variable cant accessed from the static context..your suggestion

Once again stuck in my own thinking, As per my knowledge there is a general error in java.
i.e. 'Non-static variable cant accessed from static context....'
Now the thing is that, When we are declaring any variables(non-static) and trying to access it within the same method, Its working perfectly fine.
i.e.
public class trial{
�� public static void main(String ar[]){ ////static context
�� int counter=0; ///Non static variable
�� for(;counter<10;) {
�� counter++;
�� System.out.println("Value of counter = " + counter) ; ///working fine
�� }
�� }
Now the question is that if we are trying to declare a variable out-side the method (Non-static) , Then we defenately face the error' Non-static varialble can't accessed from the static context', BUT here within the static context we declared the non-static variable and accessed it perfectly.
Please give your valuable suggestions.
Thanks,
Jeff

Once again stuck in my own thinking, As per my
knowledge there is a general error in java.
i.e. 'Non-static variable cant accessed from static
context....'
Now the thing is that, When we are declaring any
variables(non-static) and trying to access it within
the same method, Its working perfectly fine.
i.e.
public class trial{
�� public static void
main(String ar[]){ ////static context
�� int counter=0; ///Non
static variable
�� for(;counter<10;) {
�� counter++;
��
System.out.println("Value
of counter = " + counter) ; ///working fine
�� }
�� }
w the question is that if we are trying to declare a
variable out-side the method (Non-static) , Then we
defenately face the error' Non-static varialble can't
accessed from the static context', BUT here within
the static context we declared the non-static
variable and accessed it perfectly.
Please give your valuable suggestions.
Thanks,
JeffHi,
You are declaring a variable inside a static method,
that means you are opening a static scope... i.e. static block internally...
whatever the variable you declare inside a static block... will be static by default, even if you didn't add static while declaring...
But if you put ... it will be considered as redundant by compiler.
More over, static context does not get "this" pointer...
that's the reason we refer to any non-static variables declared outside of any methods... by creating an object... this gives "this" pointer to static method controller.

Non-static variable from a static context

This is the error i get . If i understand the error correctly it says im using a static variable when i shouldnt be? Or is it the other way round? below the error is the actual code....
The error...
Googler.java:27: non-static variable this cannot be referenced from a static context
          submitButton.addActionListener(new ButtonHandler());The code...
          JButton submitButton = new JButton("Submit Query");
          submitButton.addActionListener(new ButtonHandler());

thanks for the response.
I have already tried what you said but I tried it again anyway and i get the same error more less...
Googler.java:28: non-static variable this cannot be referenced from a static context
          ButtonHandler buttonHandler = new ButtonHandler();here is part of my code
public class Googler
static JTextField input1, input2;
     public static void main(String[] args)
          JFrame myFrame = new JFrame("Googler v1.0");
          Container c = myFrame.getContentPane();
          JLabel lab1 = new JLabel("Enter Google Query:");
          JLabel lab2 = new JLabel("Enter Unique API Key:");
          input1 = new JTextField(15);
          input2 = new JTextField(15);
          JRadioButton radSearch = new JRadioButton("Search Query");
          JRadioButton radCached = new JRadioButton("Cached Query");
          JButton submitButton = new JButton("Submit Query");
          ButtonHandler buttonHandler = new ButtonHandler();
          submitButton.addActionListener(buttonHandler);
          ButtonGroup group = new ButtonGroup();
          group.add(radSearch);
          group.add(radCached);Ive tried declaring buttonHandler as a static variable and this dosn't work either. I've never had this problem before it must be something silly im missing...?
Thanks
Lee

Non-static variable from static context?

Hi,
I've created a program using swing components
and I've set up a addActionListener to a button,
button.addActionListener(this);
when try and compile I get the following error:
non-static variable this cannot be referenced from a
static context
button.addActionListener(this);
I've checked site and my notes I don't seem to have
done anything different from programs that have compiled
in the past.
I'm currently doing a programming course so I'm fairly
new to Java, try not to get to advanced on me :)
Thx in advance for any help.
Chris

Well what is declared static? If I remeber right this error means that you have a static method that is trying to access data it does not have access to. Static methods cannot access data that is intance data because they do not exist in the instance (not 100% sure about this but I believe it is true, at the very least I know they do not have access to any non-static data). Post some more of your code like where you declare this (like class def) and where you set up the button.

Static variable error

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