How to detect if a graphical interface is supported?

Question

I need my Java program to have two display modes: a GUI interface and a command line interface. If I run it in Windows, OS X, or another graphical environment I should get

Answer 1

You actually have two questions:

1) Check if you run in a headless environment (no graphics). Check this method:

if (GraphicsEnvironment.isHeadless()) {
     // non gui mode
} else {
     // gui mode
}

2) Check which OS you are running under:

System.getProperty("os.name")

However, the second (2) question will return the same name even though you operate in a headless environment.