Java:How could Java classes direct program messages to the system console but error messages say to file?

Question

I run my code in Eclipse IDE and its fine. I have export it as jar file from Eclipse and run on terminal as jar file, it generates Error: java.lang.NullPointerException. Could not understand why is it so.

Answer 1

The class System has a variable out that represents the standard output, and the variable err that represents the standard error device. By default they both point at the system console. This how the standard output could be re-directed: Stream st = new Stream(new FileOutputStream("output.txt")); System.setErr(st); System.setOut(st);