setProperty("headless","true") weirdness?

[Daisy]

Can anyone provide insight on System.setProperty( "java.awt.headless" ,
"true" )?

I've been struggling with a HeadlessException in the line:
JFrame frame = new JFrame( );

So I added System.setProperty( "java.awt.headless" , "true" ) before
the JFrame call. However, JFrame still throws this error. Shouldn't
setting the property inform the JVM that it is headless?

System.setProperty( "java.awt.headless" , "true" );
try {
JFrame frame = new JFrame( );
frame.getContentPane( ).add( c );
frame.addNotify( );
} catch ( HeadlessException e ) {
printStackTrace( );
}

It is a Redhat computer running Hotspot 1.5.0_07 and Tomcat 5.5.17. It
is headless. The application is a servlet that runs fine on linux
machines with monitors. I tried the -Djava.awt.headless=true argument
long ago and still use it.

I'd really appreciate any insight on this problem,

Thanks!

 

[Gordon Beaton]

Can anyone provide insight on System.setProperty(
"java.awt.headless" , "true" )?

I've been struggling with a HeadlessException in the line:
JFrame frame = new JFrame( );

So I added System.setProperty( "java.awt.headless" , "true" ) before
the JFrame call. However, JFrame still throws this error. Shouldn't
setting the property inform the JVM that it is headless?

I believe you need to set the property before
java.awt.GraphicsEnvironment is loaded and initialized.

/gordon

 

[Stanimir Stamenkov]

I've been struggling with a HeadlessException in the line:
JFrame frame = new JFrame( );

So I added System.setProperty( "java.awt.headless" , "true" ) before
the JFrame call. However, JFrame still throws this error. Shouldn't
setting the property inform the JVM that it is headless?

I believe that's what we expect - you can't construct a Frame given
you're in a headless environment, why do you need to?

 

[Norman D.]

Here is a link which might be helpful:

http://java.sun.com/developer/technicalArticles/J2SE/Desktop/headless/

--Norman

 

[Daisy]

Thanks everyone who gave advice!

Here's the revised code which resolved the problem:

System.setProperty( "java.awt.headless" , "true" );
Toolkit tk = Toolkit.getDefaultToolkit( );

try {
// JFrame frame = new JFrame( );
// frame.getContentPane( ).add( c );

JPanel panel = new JPanel( );
panel.add( c );
panel.addNotify( );

In addition to setting the headless property, I had to swap from Frame
to Panel.

Thanks,

Jeff