Flow Control with exception

Question

When I run the following code, there are two result.

 package scjp;

    public class ExceptionTest {

        public static void main(String[] args) {
            ExceptionTest test = new ExceptionTest();
            test.method1();
        }

        public void method1() {
            try {
                System.out.println("Try Block");

                if (!true) {
                    return;
                } else {
                    throw new RuntimeException();
                }
            }finally {
                System.out.println("Finally Block");
            }
        }
    }

One result is

Try Block
Exception in thread "main" java.lang.RuntimeException
    at scjp.ExceptionTest.method1(ExceptionTest.java:17)
    at scjp.ExceptionTest.main(ExceptionTest.java:7)
Finally Block

and the other,

Try Block
Finally Block
Exception in thread "main" java.lang.RuntimeException
    at scjp.ExceptionTest.method1(ExceptionTest.java:17)
    at scjp.ExceptionTest.main(ExceptionTest.java:7)

Each time I am running the above code, the answer is changing. In my understanding, it should always be same result. Can you help me something???

Answer 1

The system error output stream (the stack trace above, likely in red in your console) is different than the system output stream (your System.out.println() statements). Hence error messages can be out of sync with normal console output since both streams write to the console, but independently of each other. The differences are as follows:

System.out.println("Some text");

prints to the out stream

System.err.println("Error occurred!");

prints to the error stream

The two can get intermixed when outputting to the same console.