Throw statement reports IOException not handled

Question

class simpleShell{
    Process sh;
    simpleShell(String shell)  {
        try {
            sh = Runtime.getRuntime().exec(shell);
        }catch (Exception e){
            throw e;
        }
    }

}
class Main{
public satic void main(String args[]){

try {
    simpleShell ss = new simpleShell("sh");
}catch{
    //do something
}

I am trying to make a shell class for an app. But the IDE keeps reporting "IOException" not handled and suggests me to use throws. I want to handle exceptions when function called not ignore them. I though constructors cant throw but some says otherwise. I even tried doing a separate method to create the process and throw the exception and tried throwing other exceptions. But same report.

The report is at throw statement.

You're throwing an exception from the method but it does not declare it as such. You need to add `throws Exception` to the signature or __not__ use the `throw e` inside the method. — rdas, Mar 02 '21 at 04:14
First: Java Class names start with a capital letter. Second: Of course can constructors throw Exceptions. — Benjamin M, Mar 02 '21 at 04:15
What does this snippet of code have to do with constructors throwing exceptions? Are you sure this code is representative of what you're asking about? — Sotirios Delimanolis, Mar 02 '21 at 04:18
Sorry for poor question quality.But its not similar to those posted. Can u see the edit and help me again. — Riyadh Kabir, Mar 02 '21 at 05:22

tgdavies · Answer 1 · 2021-03-02T05:37:53.033

0

A method (or constructor) which calls a method which has throws IOException (or any other type of exception of course) needs to either catch the exception, or declare that it throws it too.

When a method declares that it throws an exception, then its callers must also either catch or declare the exception.

So you can either:

void create(String shell){
        try {
            sh = Runtime.getRuntime().exec(shell);
        }catch (IOException e){
            // handle the exception in some way
        }
}

or

void create(String shell) throws IOException {
   sh = Runtime.getRuntime().exec(shell);
}

If you want to catch the exception, do something, and then rethrow it you need to declare that your method throws the exception:

void create(String shell) throws IOException {
        try {
            sh = Runtime.getRuntime().exec(shell);
        }catch (IOException e){
            // handle the exception in some way
            // then rethrow it
            throw e;
        }
}

edited Mar 02 '21 at 05:37

answered Mar 02 '21 at 04:21

tgdavies

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Parhaps my qeustion was not clear. I want to catch the exception which is ok. But i want to throw the the catched exception to the caller Function. When ever i try to thow it, ide reports IOException not handled – Riyadh Kabir Mar 02 '21 at 05:14
@RiyadhKabir I've added an example showing that behaviour – tgdavies Mar 02 '21 at 05:21
But doent throws supress the exception?What if the exec sends IOExcption and i cant catch it cause of throws – Riyadh Kabir Mar 02 '21 at 05:28
No, `throws` forces callers of the function to either catch or declare the exception. – tgdavies Mar 02 '21 at 05:38

Throw statement reports IOException not handled

1 Answers1