Cant figure out the problem

Question

import javax.swing.*;
import javax.swing.event.*;
import java.awt.*;
import java.awt.event.*;
public class myProject extends JFrame implements ActionListener{ 
        JButton search=new JButton("Search");
        public DefaultListModel df=new DefaultListModel();
        public JList list1=new JList(df);
         check c=new check();
     public myProject(){       
          search.addActionListener(this);
     public void design(){ 
        JPanel jp1=new JPanel();
        jp1.add(search);
         getContentPane().setLayout(new BorderLayout());
         getContentPane().add(list1,BorderLayout.CENTER);
         setVisible(true);
         getContentPane().add(jp1,BorderLayout.SOUTH);            
         setSize(450,180);
     public static void main(String []args){
       myProject j=new myProject();         
          j.design();    
   public void actionPerformed(ActionEvent event) {
        myProject j=new myProject();
        if(event.getSource()==search){
            list1.removeAll();
          Object p[]={"hi","hello"
            df.addElement(p[0]);
            df.addElement(p[1]);
            c.testing();        
public class check {
  myProject  mp;
    public check() {
    public void testing(){
           mp=new myProject();
         mp.df.addElement("how");
}I wrote this two class the output is
hi
hello
these two are printed in JList why not "how"??
is my code writing style ok?? i always get messed up with object
plz suggest me a better way of writing this code
thanks in advance

Answer 1

Basically you have to tell the instance of the check class that you create what instance of the project class it is that it should be checking. One place to do this is in the constructor of the check class. (eg if it is to meant to check one project only).
Moving the code that initialises the buttons and stuff into the projects constructor, and putting your main()'s contents into an invokeLater() it would look like:
import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.DefaultListModel;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JList;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
public class MyProject extends JFrame implements ActionListener{ 
    private JButton search;
    private DefaultListModel df;
    private JList list1;
    private ProjectChecker c;
    public MyProject(){       
        search = new JButton("Search");
        df = new DefaultListModel();
        list1 = new JList(df);
        c = new ProjectChecker(this);
        search.addActionListener(this);
    public void design(){ 
        JPanel jp1=new JPanel();
        jp1.add(search);
        getContentPane().setLayout(new BorderLayout());
        getContentPane().add(list1,BorderLayout.CENTER);
        getContentPane().add(jp1,BorderLayout.SOUTH);            
        setVisible(true);
        setSize(450,180);
    public void actionPerformed(ActionEvent event) {
        if(event.getSource() == search) {
            list1.removeAll();
            Object p[]={"hi", "hello"};
            df.addElement(p[0]);
            df.addElement(p[1]);
            c.testing();        
    public DefaultListModel getListModel() {
        return df;
    public static void main(String []args){
            SwingUtilities.invokeLater(new Runnable() {
                public void run() {
                    MyProject j = new MyProject();         
                    j.design();    
}and
public class ProjectChecker {
    private MyProject proj;
    public ProjectChecker(MyProject proj) {
        this.proj = proj;
    public void testing(){
        proj.getListModel().addElement("how");
}Notice how a couple of "new MyProject()" lines have been removed.