Creating a console in Java

Question

When I try to use java.lang.System.console(), I get a null pointer. I can still write to out and read from in, but this only works when I run straight from my IDE. When I run the .jar file directly, nothing happens. How can I create a console like I'd see using std::cout for use in Java?

Edit: I was hoping to just create one, rather than understand why I don't have one, since I need one for my program's operation.

Answer 1

Perhaps you're trying to get the console by double-clicking in the jar

Try creating a batch file that opens the console for you.

You can however create a console using Swing and redirect standard input/output there.

Source: Create Java console inside a GUI panel

Answer 2

How are you running the JAR file exactly? That would be the expected behavior for double-clicking its icon in Windows Explorer, as Kelly alluded to, but not for firing it up from the command line.

From the Console entry in the API (emphasis mine):

Whether a virtual machine has a console is dependent upon the underlying platform and also upon the manner in which the virtual machine is invoked. If the virtual machine is started from an interactive command line without redirecting the standard input and output streams then its console will exist and will typically be connected to the keyboard and display from which the virtual machine was launched. If the virtual machine is started automatically, for example by a background job scheduler, then it will typically not have a console.