Component Arrays

[Tetsuo Suzuki]

Ran into something a bit strange; if I have a component array it won't allow me to initialize each component outside of the constructor. An example of what I mean:

public class win extends JFrame{
JLabel[] x = new JLabel[2];
x[0] = new JLabel("FUBAR"); // <-- error
}

But...

  
public class win extends JFrame{
JLabel[] x = new JLabel[2];
public win(){
x[0] = new JLabel("foo"); // <-- happy
}
}

Is assigning the 'new' keyword here doing something executable that can't be in declaration?
Thanks much,
Tetsuo!

[Manfred Leonhardt]

Hi Tetsuo,
You are not seeing something a little strange. You are seeing how java works!
An assignment (to any variable) can be done in two ways:
1) Along with declaration:

int i = 45;
JLabel label = new JLabel( "Name" );
JLabel[] labels = new JLabel[20];

2) Inside any code block (defined by braces {}):

public class Test
{
  Jlabel label;
  label = new JLabel( "Fails" ); // Fails because not inside any block
  JButton[] buttons = new JButton[2];
  {
    label = new JLabel( "Name" );
    buttons[0] = new JButton( "Name" );
  }
  buttons[1] = new JButton( "Fails2" ); // Fails because not inside any block
  public void method()
  {
    label = new JLabel( "Name2" );
    buttons[1] = new JButton( "Name2" );
  }
}

Java will not let you perform assignments outside code blocks with the exception of number 1 above.
Regards,
Manfred.
[ March 14, 2002: Message edited by: Manfred Leonhardt ]

[Colin Humber]

JLabel[] x={new JLabel("Label1"),
new JLabel("label2")};