AWT

[Manoj Syoran]

Sir When I run this code I get a NullPointerException.Please help me in finding the reason for this error in my code.

class Sys_adm extends Frame implements ActionListener,ItemListener
 {
Choice abc;
Panel p1,p2,p3;
Button btn1,btn2,bt1;
Button bt2;
TextField txt1,txt2,txt3,txt4,txt5,txt6;
Label lb1,lb2,lb3,lb4,lb5,lb6;
Label lb15,lb16;
MenuBar mbar;
Menu m1;
Menu item1;
MenuItem item2;
MenuItem item3,item4,item5;
MenuItem item6,item7,item8,item9,item10,item11,item12;
MenuItem item13,item14,item15,item16,item17,item18,item19;
String st1,st2;
Statement st;
Connection con;
ResultSet rs;
Sys_adm(String str)
 {
super(str);
setLayout(new FlowLayout());
lb1=new Label("Item Name:",Label.RIGHT);
lb2=new Label("Item Id:",Label.RIGHT);
lb3=new Label("Stock NO.:",Label.RIGHT);
lb4=new Label("Price:",Label.RIGHT);
lb5=new Label("Text Description:",Label.RIGHT);
lb6=new Label("Picture:",Label.RIGHT);
txt1=new TextField(10);
txt2=new TextField(10);
txt3=new TextField(10);
txt4=new TextField(10);
txt5=new TextField(10);
txt6=new TextField(10);
txt1.setBackground(Color.cyan);
txt2.setBackground(Color.cyan);
txt3.setBackground(Color.cyan);
txt4.setBackground(Color.cyan);
txt5.setBackground(Color.cyan);
txt6.setBackground(Color.cyan);
bt1=new Button("ADD");
bt2=new Button("CANCEL");
////////////////////
btn1=new Button("OK");
btn2=new Button("Cancel");
p1=new Panel(new GridLayout(6,1));
p2=new Panel(new GridLayout(6,1));
p3=new Panel(new GridLayout(1,2));
p1.add(lb1);
p2.add(txt1);
p1.add(lb2);
p2.add(txt2);
p1.add(lb3);
p2.add(txt3);
p1.add(lb4);
p2.add(txt4);
p1.add(lb5);
p2.add(txt5);
p1.add(lb6);
p2.add(txt6);
p3.add(bt1);
p3.add(bt2);
add(p1);
add(p2);
add(p3);
p2.setVisible(false);
p3.setVisible(false);
abc=new Choice();
abc.add("ADD");
abc.add("UPDATE");
abc.add("DELETE");
add(abc);
add(btn1);
add(btn2);
mbar=new MenuBar();
setMenuBar(mbar);
m1=new Menu("AUTOMECHANICS");
item1=new Menu("WRENCHES");
item2=new MenuItem("SCREW DRIVER");
item3=new MenuItem("ADJUSTABLE");
item4=new MenuItem("COMBINATION");
item5=new MenuItem("PIPE");
item6=new MenuItem("FILES");
item7=new MenuItem("CHISELS");
item8=new MenuItem("SCISSORS");
item9=new MenuItem("TAPES");
item10=new MenuItem("HAMMERS");
item11=new MenuItem("BYCYCLE LOCKS");
item12=new MenuItem("LUGGAGE LOCKS");
item13=new MenuItem("SECURITY DOOR LOCKS");
item14=new MenuItem("AIR COMPRESSORS");
item15=new MenuItem("CRUSHER");
item16=new MenuItem("DRILL");
item17=new MenuItem("GRINDING MACHINE");
item18=new MenuItem("FREEZE COMPRESSORS");
item19=new MenuItem("PUMP COMPRESSORS");
item1.add(item3);
item1.add(item4);
item1.add(item5);
m1.add(item1);
m1.add(item2);
Menu m2=new Menu("DOOR LOCKS");
Menu m3=new Menu("HAND TOOLS");
Menu m4=new Menu("POWER TOOLS");
Menu m5=new Menu("COMPRESSORS");
Menu m6=new Menu("MY ACCOUNTS");
Menu m7=new Menu("HELP");
mbar.add(m1);
mbar.add(m2);
mbar.add(m3);
mbar.add(m4);
mbar.add(m5);
mbar.add(m6);
mbar.add(m7);
m2.add(item11);
m2.add(item12);
m2.add(item13);
m3.add(item6);
m3.add(item7);
m3.add(item8);
m3.add(item9);
m3.add(item10);
m4.add(item14);
m4.add(item15);
m4.add(item16);
m4.add(item17);
m5.add(item18);
m5.add(item19);
try
{
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
con=DriverManager.getConnection("Jdbc:Odbc:Syst_ad");
st=con.createStatement();
}
catch(Exception ex)
{
///////////////
}
item1.addActionListener(this);
item2.addActionListener(this);
item4.addActionListener(this);
item5.addActionListener(this);
item6.addActionListener(this);
item7.addActionListener(this);
item8.addActionListener(this);
bt1.addActionListener(this);
bt2.addActionListener(this);
txt1.addActionListener(this);
txt2.addActionListener(this);
txt3.addActionListener(this);
txt4.addActionListener(this);
txt5.addActionListener(this);
btn1.addActionListener(this);
btn2.addActionListener(this);
btn2.setActionCommand("hello");
abc.addItemListener(this);
////////////////////////////
MyWindowAdapter adapter=new MyWindowAdapter(this);
addWindowListener(adapter);
}
////////////////////////
public void itemStateChanged(ItemEvent ie)
{
st1=abc.getSelectedItem();
}
/////////////////
public void actionPerformed(ActionEvent ae)
{
st2=ae.getActionCommand();
if(st1.equals("DELETE")&st2.equals("OK"))
{
try
{
Dialog1 d=new Dialog1(null,"Confirmation");
d.setVisible(true);
}
catch(Exception excp)
{
//////////////
}
}
else if(st2.equals("PIPE"))
{
Label lbl[]=new Label[5];
Panel p8=new Panel(new GridLayout(6,1));
////////////////
try
{
rs=st.executeQuery("SELECT Item_Name,Item_Id,Stock_No,Price,Text_Desc FROM item_data WHERE Item_Id LIKE 'NMP43K'");
System.out.println("Data loaded Successfully");
while(rs.next())
{
int p=rs.getInt(4);
String string=Integer.toString(p);
lbl[0]=new Label(rs.getString(1));
lbl[1]=new Label(rs.getString(2));
lbl[2]=new Label(rs.getString(3));
lbl[3]=new Label("$"+string);
lbl[4]=new Label(rs.getString(5));
}
}
catch(Exception sqe)
{
System.out.println(sqe.getMessage());
}
for(int i=0;i<=4;i++)
{
p8.add(lbl[i]);
lbl[i].setForeground(Color.blue);
}
add(p8);
}
else if(st1.equals("ADD")&st2.equals("OK"))
{
p1.setVisible(true);
p2.setVisible(true);
p3.setVisible(true);
abc.setVisible(false);
btn2.setVisible(false);
btn1.setVisible(false);
}

else if(st1.equals("UPDATE")&st2.equals("OK"))
{
update up=new update();
up.setSize(800,600);
up.setVisible(true);
}

else if(st2.equals("ADD"))
{
try
{
st.executeQuery("Insert into item_data Values('"+txt1.getText()+"','"+txt2.getText()+"','"+txt3.getText()+"','"+txt4.getText()+"','"+txt5.getText()+"')");
}
catch(Exception xe)
{
///////////////
}
txt1.setText("");
txt2.setText("");
txt3.setText("");
txt4.setText("");
txt5.setText("");
}

else if(st2.equals("hello"))
{
dispose();
}
else
{
dispose();
}
}
}

[Jeff Verdegan]

You need to state exactly where the NPE is happening. Paste in the exactly, complete error message, including the stack trace, and make it clear which line is causing it.

[Tim Moores]

Never do this:

catch(Exception ex)
{
///////////////
}

At the very least print a message to where you will see it. For example, if there's a problem in line 134 or 135, the con or st variables will be null, yet you won't know anything about it.

[Manoj Syoran]

Sir I am sending image of exception on the commandline

[Matthew Brown]

Something isn't right with that image. Just tell us which line of the code you've posted the error is occurring on (you'll have to convert the file line number it's reporting to you to the line of code that you've posted, if they aren't exactly the same).

[Jeff Verdegan]

Manoj Syoran wrote:Sir I am sending image of exception on the commandline

PostTextNotScreenshots (<-- It's a link. Click it.)

And of course we can't see your image. Did you notice that it is rooted at your C: drive? You wouldn't expect the entire world to be able to get to your computer just via "C:", would you?

[William Brogden]

You can capture the text in a Command Prompt window as simple text - screen shots are a waste of bandwidth and wont show the entire stack trace.

1. right click on the upper left corner to get a menu
2. pick the Edit -> select all option - selected text will be highlighted
3. press enter - text will be on clipboard

[Manoj Syoran]

Sir, Here is the error code.

Microsoft Windows XP [Version 5.1.2600]
(C) Copyright 1985-2001 Microsoft Corp.

C:\Documents and Settings\Mahesh>cd\

C:\>jkm

C:\>cd prog*

C:\Program Files>cd java

C:\Program Files\Java>cd jdk*

C:\Program Files\Java\jdk1.5.0>cd bin

C:\Program Files\Java\jdk1.5.0\bin>javac product.java

C:\Program Files\Java\jdk1.5.0\bin>java product
driver loaded
connection created
data loaded
Data loaded Successfully
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
        at java.awt.Container.addImpl(Container.java:1019)
        at java.awt.Container.add(Container.java:351)
        at Sys_adm.actionPerformed(product.java:217)
        at java.awt.MenuItem.processActionEvent(MenuItem.java:597)
        at java.awt.MenuItem.processEvent(MenuItem.java:556)
        at java.awt.MenuComponent.dispatchEventImpl(MenuComponent.java:298)
        at java.awt.MenuComponent.dispatchEvent(MenuComponent.java:286)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:466)
        at java.awt.EventDispatchThread.pumpOneEventForHierarchy(EventDispatchTh
read.java:234)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThre
ad.java:163)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:157)

        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:149)

        at java.awt.EventDispatchThread.run(EventDispatchThread.java:110)

C:\Program Files\Java\jdk1.5.0\bin>

[Rob Spoor]

Manoj Syoran wrote:

Data loaded Successfully
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
        at java.awt.Container.addImpl(Container.java:1019)
        at java.awt.Container.add(Container.java:351)
        at Sys_adm.actionPerformed(product.java:217)

In your actionPerformed method, on line 217, you are adding something that's null to a container. I see only one line that could be the cause, p8.add(lbl[i]);. This would mean that lbl[i] is null, and that can only be the case if your database query returned 0 results.