JPanel Array -- NullPointerException

[tomzhi]

I am new to Java, learning GUI. I am trying to create a TabbedPane
with 10 tabs, by using array of JPanel. However, JPanel arrays are
always null. I do not understand why they are null when they are
arrays but not otherwise. I would appreciate explanation and help on
this code. Thanks

public static void main(String[] args) {
JTabbedPane tab = new JTabbedPane();

int i;
JTextField[] text = new JTextField[10]; //
textfield to add to each panel
JPanel [] panel = new JPanel[10]; //array
of panel

//name of each tab
String [] name = {"One",
"Two","Three","Four","Five","Six","Seven","Eight","Nine","Ten"};

for (i=1;i<10;i++) {
panel.add(text); //
NullPointerException here
tab.addTab(name,panel);
}

System.out.println(tab);
JFrame frame = new JFrame("Testing");
frame.add(tab);
frame.setSize(500,500);
frame.setVisible(true);
}

 

[Chris Dollin]

I am new to Java, learning GUI. I am trying to create a TabbedPane
with 10 tabs, by using array of JPanel. However, JPanel arrays are
always null. I do not understand why they are null when they are
arrays but not otherwise.

When you create an array of references using `new ClassName[N]`,
each element of that array is null. If you want to put something
interesting into the elements, you have to do so yourself.

[It's null because there's no [general] way of knowing how to construct
an element to go into that slot.]

 

[tomzhi]

I am new to Java, learning GUI. I am trying to create a TabbedPane
with 10 tabs, by using array of JPanel. However, JPanel arrays are
always null. I do not understand why they are null when they are
arrays but not otherwise.

When you create an array of references using `new ClassName[N]`,
each element of that array is null. If you want to put something
interesting into the elements, you have to do so yourself.

[It's null because there's no [general] way of knowing how to construct
an element to go into that slot.]

--
Chris "loopy" Dollin

Hewlett-Packard Limited Cain Road, Bracknell, registered no:
registered office: Berks RG12 1HN 690597 England

Chris, but how do I go about doing it?
panel =?

the right said need to be a JPanel too.

 

[tomzhi]

Thanks. I figured out that I just needed to add panel=new JPanel()
and box=new JComboBox();