"AWT-EventQueue-0" java.lang.NullpointerException
i keep getting this at ExsysGui.actionperformed (ExsysGUI.java:78)
i dun understand why it say i send "null" there?
can someone help? thanks in advance
-
publicclass Exsys
{
publicstaticvoid main(String args[])
{
new ExsysGUI("Internet Connection Sharing Trouble Shooter");
}
}
publicclass Cont{
privateint rr;
public Cont(int name)
{rr = name;
}
publicint getrr()
{
return rr;
}
}
--
import java.sql.*;
import java.lang.*;
publicclass esys
{
private String a =new String();
privateint x;
private Connection conn;
private ResultSet rs;
private Statement stat;
public esys(int name)
{
x = name;
try
{
Class.forName("com.mysql.jdbc.Driver");
conn = DriverManager.getConnection("jdbc:mysql://localhost/esys","root","weijie888");
stat = conn.createStatement();
rs = stat.executeQuery("SELECT QUESANS FROM esys WHERE ID = '" + x +"' ");
while(rs.next()){
a = rs.getString("QUESANS");
}
}
catch (SQLException sql)
{
sql.printStackTrace();
}
catch (ClassNotFoundException c)
{
c.printStackTrace();
}
}
public String geta(){
return a;
}
}
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.lang.*;
publicclass ExsysGUIextends JFrame
implements ActionListener
{
private JTextArea display;
private JButton Start;
private JButton yes;
private JButton no;
private JButton how;
private JButton why;
private esys esys;
Cont yy;
private Yes hh;
private No cc;
private How ww;
private Why ee;
public ExsysGUI(String title)
{
setTitle(title);
buildGUI();
pack();
setSize(600,400);
setVisible(true);
}
privatevoid buildGUI()
{ Container contentPane = getContentPane();
contentPane.setLayout(new BorderLayout());
display =new JTextArea(20,70);
display.setFont (new Font("Monospaced", Font.BOLD, 12));
display.setBackground(new Color(0xe0e0e0));
display.setEditable(false);
Start =new JButton("START");
Start.addActionListener(this);
yes =new JButton("YES");
yes.addActionListener(this);
no =new JButton("NO");
no.addActionListener(this);
how =new JButton("HOW");
how.addActionListener(this);
why =new JButton("WHY");
why.addActionListener(this);
JPanel inputPanel =new JPanel();
inputPanel.add(Start);
inputPanel.add(yes);
inputPanel.add(no);
inputPanel.add(how);
inputPanel.add(why);
contentPane.add("Center", display);
contentPane.add("South", inputPanel);
}
publicvoid actionPerformed(ActionEvent e)
{
if (e.getSource() == Start)
{
int name = 1;
esys a =new esys(name);
Cont yy =new Cont(name);
display.append(a.geta() +"\n");
}
if (e.getSource() == yes)
{
int acquireid = yy.getrr();
Yes hh =new Yes(acquireid);
display.append(hh.getyes() +"\n");
}
if (e.getSource() == no)
{
int acquireid = yy.getrr();
No cc =new No(acquireid);
display.append(cc.getno() +"\n");
}
if (e.getSource() == how)
{
int acquireid = yy.getrr();
How ww =new How(acquireid);
display.append(ww.gethow()+"\n");
}
if (e.getSource() == why)
{
int acquireid = yy.getrr();
Why ee =new Why(acquireid);
display.append(ee.getwhy()+"\n");
}
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
}
import java.sql.*;
import java.lang.*;
publicclass Yes
{
private String yes =new String();
privateint yesID = 0;
privateint x;
private Connection conn;
private ResultSet rs;
private Statement stat;
public Yes(int ID)
{
x = ID;
try
{
Class.forName("com.mysql.jdbc.Driver");
conn = DriverManager.getConnection("jdbc:mysql://localhost/esys","root","weijie888");
stat = conn.createStatement();
rs = stat.executeQuery("SELECT ID , QUESANS FROM esys WHERE YES = '" + x +"' ");
while(rs.next()){
yes = rs.getString("QUESANS");
yesID = Integer.parseInt(rs.getString("ID"));
}
}
catch (SQLException sql)
{
sql.printStackTrace();
}
catch (ClassNotFoundException c)
{
c.printStackTrace();
}
}
Cont update =new Cont(yesID);
public String getyes(){
return yes;
}
}
-
import java.sql.*;
import java.lang.*;
publicclass No
{
private String no =new String();
privateint noID = 0;
privateint x;
private Connection conn;
private ResultSet rs;
private Statement stat;
public No(int noID)
{
x = noID;
try
{
Class.forName("com.mysql.jdbc.Driver");
conn = DriverManager.getConnection("jdbc:mysql://localhost/esys","root","weijie888");
stat = conn.createStatement();
rs = stat.executeQuery("SELECT ID , QUESANS FROM esys WHERE NO = '" + x +"' ");
while(rs.next()){
no = rs.getString("QUESANS");
noID = Integer.parseInt(rs.getString("ID"));
}
}
catch (SQLException sql)
{
sql.printStackTrace();
}
catch (ClassNotFoundException c)
{
c.printStackTrace();
}
}
Cont update =new Cont(noID);
public String getno(){
return no;
}
}
