Difference in calling sequence while rethrowing exceptions

Question

Consider the following class with methods: a() calling b() which in turn calls c().

public class ReThrower {

    public static void a(int a1){
        try{
           a1+=1;
           b(a1);
        }
        catch(ArithmeticException e){
            System.out.println("Exception caught at a");
            throw e;
        }
    }

    public static void b(int b1){
        try{
            b1+=1;
            c(b1);
        }
        catch(ArithmeticException e){
            System.out.println("Exception caught at b");
            throw e;
        }

    }

    public static void c(int c1){
        int zero=0,result;
        try{
            result=c1/zero;
        }
        catch(ArithmeticException e){
            System.out.println("Exception caught at c");
            e.printStackTrace();
            throw e;
        }

    }

    public static void main(String[] args) {
        a(5);
    }

}

When i ran the above code, the initial output received was:

Exception caught at c
java.lang.ArithmeticException: / by zero
Exception caught at b
Exception caught at a
    at com.atul.security.ReThrower.c(ReThrower.java:31)
    at com.atul.security.ReThrower.b(ReThrower.java:20)
    at com.atul.security.ReThrower.a(ReThrower.java:10)
    at com.atul.security.ReThrower.main(ReThrower.java:46)
Exception in thread "main" java.lang.ArithmeticException: / by zero
    at com.atul.security.ReThrower.c(ReThrower.java:31)
    at com.atul.security.ReThrower.b(ReThrower.java:20)
    at com.atul.security.ReThrower.a(ReThrower.java:10)
    at com.atul.security.ReThrower.main(ReThrower.java:46)

Even before the c() printed the complete stacktrace, the sysout included in b() and a() has already been executed. However,When i ran it again, the output changed as such:

    Exception caught at c
Exception caught at b
Exception caught at a
java.lang.ArithmeticException: / by zero
    at com.atul.security.ReThrower.c(ReThrower.java:31)
    at com.atul.security.ReThrower.b(ReThrower.java:20)
    at com.atul.security.ReThrower.a(ReThrower.java:10)
    at com.atul.security.ReThrower.main(ReThrower.java:46)
Exception in thread "main" java.lang.ArithmeticException: / by zero
    at com.atul.security.ReThrower.c(ReThrower.java:31)
    at com.atul.security.ReThrower.b(ReThrower.java:20)
    at com.atul.security.ReThrower.a(ReThrower.java:10)
    at com.atul.security.ReThrower.main(ReThrower.java:46)

Given that this is single threaded, why is there a change in behaviour in multiple runs?

score 3 · Answer 1 · edited May 23 '17 at 11:56

3

e.printStacktrace prints to System.err whereas you print the rest of the lines with System.out. And when you print to both streams the result can look out of order.

edited May 23 '17 at 11:56

Community

1
1

answered Jun 18 '13 at 11:19

assylias

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But it's not multithreaded - surely this interleaving would be deterministic? – selig Jun 18 '13 at 11:21
2

Can't see why; stream buffering is asynchronous. @assylias is correct here. – Bathsheba Jun 18 '13 at 11:23

Difference in calling sequence while rethrowing exceptions

1 Answers1