Open a text file in the default text editor… via Java?

Question

OK. Simple question. Maybe not so simple answer, though:

I have a file I downloaded in Java, and I know that it's a text file. Is there any way that I can use Java to open that text file in whatever the default text editor is? It has to work for all OS's, otherwise I would just make it open with Notepad.

:\ I guess that if there's no way to do this I could use JOptionPane and show the contents of the text file...

Answer 1

You can do that with:

java.awt.Desktop.getDesktop().edit(file);

This links to the tutorial article on java.awt.Desktop:

Java™ Standard Edition version 6 narrows the gap between performance and integration of native applications and Java applications. Along with the new system tray functionality, splash screen support, and enhanced printing for JTables , Java SE version 6 provides the Desktop API (java.awt.Desktop) API, which allows Java applications to interact with default applications associated with specific file types on the host platform.

It is cross-platform, but may not be supported everywhere. There is a method you can call to check whether the Desktop API is available, called isDesktopSupported (see the link for more explanation). I was using this API the other day to open PDFs in a Swing client.

Unfortunately there is a known bug affecting some Windows platforms (XP and 2003) that will crash the JVM. Write once, debug everywhere, as usual. Anyway, for Windows there is a nice workaround which still uses the user's preferred application:

if (System.getProperty("os.name").toLowerCase().contains("windows")) {
  String cmd = "rundll32 url.dll,FileProtocolHandler " + file.getCanonicalPath();
  Runtime.getRuntime().exec(cmd);
} 
else {
  Desktop.getDesktop().edit(file);
}

Answer 2

Desktop.getDesktop().edit(File f);

Answer 3

Certainly you could configure in the text editor and use Runtime.exec to start it. But I can't think of any way to determine the default editor, especially in a system-independent fashion.

Maybe your best option is to identify which of the several most popular platforms you're on and then find a way to start the default editor on that platform. Eg, on Window you'll get the default editor if you do "start filename.txt", and I'm pretty sure there's a Linux equivalent.