How to print only exit code ,when java program gives exception(running java program from shellscropt)?

Question

I have a java program which throws some exception,I tried executing it from shell script and printing 0 on failure and 1 on successful execution of java program.But It also printing the Exception onto console I just want to print exit code only.How to do this ?.Any suggestion are appreciated .

following are my Java program and script files Test.Java

public class EchoTest {
    public static void main (String args[]) {
    System.out.println ("scuccess Prasad Bezavada "+(2/0));
    }
}

Test.sh(script file)

java Test
if [ $? -eq 0 ]
then echo "1"
else echo "0"
fi

getting the following out put

$sh Test.sh
    Exception in thread "main" java.lang.ArithmeticException: / by zero
        at EchoTest.main(EchoTest.java:3)
    0
$

Expecting output is like below(i.e just want to skip the exception message)

$sh Test.sh 0 $

a word of warning: every other system would expect a 0 for success and any other value for a series of error codes — malarres
– malarres, Commented Jul 29, 2015 at 6:07

Thirupathi Thangavel · Accepted Answer · 2015-07-29 05:58:43Z

2

Try this.

java Test 2> /dev/null
if [ $? -eq 0 ]
then echo "1"
else echo "0"
fi

answered Jul 29, 2015 at 5:58

Thirupathi Thangavel

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5 Comments

prasad Over a year ago

Hi @t_thirupathi, thank for your response ,it is just returning 0(zero) in both success and failure cases

malarres Over a year ago

that's because $? holds the success code of the redirection (>) rather than the java sentence

Thirupathi Thangavel Over a year ago

@prasad That means there is some other problem with running java Test, so it is exiting with non-zero always (in which case the script outputs 0).

Thirupathi Thangavel Over a year ago

@malarres No, redirection does not matter. $? has the exit code of the last command and redirection is not a command.

malarres Over a year ago

then my other answer is more complex than needed. will remove right now

malarres · Accepted Answer · 2015-07-29 06:01:04Z

1

you have to catch the exceptions. After that, you would be able to output exactly what you want. on your example:

public class EchoTest {
public static void main (String args[]) {
    try{
        System.out.println ("scuccess Prasad Bezavada "+(2/0));
    } catch (Exception e){
        // doing nothing is ok for your intended behaviour
    }
}
}

answered Jul 29, 2015 at 6:01

malarres

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1 Comment

hoijui Over a year ago

you might also want to consider catching even Throwable instead of Exception, as it includes also Errors (including for example OutOfMemoryError).

Fernando Martín Besteiro · Accepted Answer · 2015-07-29 13:06:04Z

First of all, you would like your Java program to return a value (either 1 or 0). In our case we will consider that if an exception is thrown, 1 will be returned and 0 otherwise. Also, exception will be hid (which is a bad practice. You should always log exceptions at least if you are not willing to show it on screen)

public class EchoTest {
    public static void main (String args[]) {
        try {
            System.out.println ("scuccess Prasad Bezavada "+(2/0));
            System.exit(0);
        }
        catch (Exception e) {
            // log your exception here
            System.exit(1);
        }
    }
}

Once this is done then what you will need to work on is on getting java's output code.

java Test
output = $?
# do some logic here..
if [[ $output -eq 0 ]]; then
    echo "executed"
else
    echo "exception thrown"
fi

Finally, this will indeed return either 1 or 0 depending on execution ignoring exception case, which is what you actually requested.

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