java:280: 'void' type not allowed here

[Farakh khan]

Hello,

I am trying here to print and send stackTrace in my email to fix the errors.
I have writtent the following methods

	public static void errorMsg(String subject, String msg) throws Exception{
		System.out.println(msg);
		SendEmail.send("[e-mail]","[e-mail]",subject,msg); 		
	}

I called this method as follow:

try{
} catch (Exception e) {	
	errorMsg("ERROR occured whilst un-zip file", e.printStackTrace());
}

but it throws following exception:

C:\Program Files (x86)\Java\Tomcat7.2\webapps\ROOT\WEB-INF\classes>javac *.java
FileManager.java:280: 'void' type not allowed here
        errorMsg("ERROR occured whilst un-zip file", e.printStackTrace());
                                                                      ^

I tried to another place as:

try{
} catch (Exception e) {	
	fm.errorMsg("ERROR.MI.BulkUpload.java<br>", "Please check stackTrace()");
}

and it throws this exception:

C:\Program Files (x86)\Java\Tomcat7.2\webapps\ROOT\WEB-INF\classes>
BulkUpload.java:265: unreported exception java.lang.Exception; must be caught or
 declared to be thrown
        fm.errorMsg("ERROR.MI.BulkUpload.java<br>", "Please check stackTrace()");
                   ^

Kindly help me to fix it.

Thanks & best regards

[John Jai]

Before going to the context, I notice you have tried to set a code tag but unsuccessful using [cpde]. To use code tags you can easily select the fragment you have to highlight as code and then click the Code button.

1. The printStackTrace() method does not return a String but is void and hence you cannot send it as a String argument to another method.

2. The second error is because the errorMsg() method throws an Exception which you do not handle. You should handle it in the catch clause again. Or include a throws Exception clause in the method declaration similar to one you have in errorMsg() method.

[Farakh khan]

John Jai wrote:Before going to the context, I notice you have tried to set a code tag but unsuccessful using [cpde]. To use code tags you can easily select the fragment you have to highlight as code and then click the Code button.

Sorry for that. I have corrected

1. The printStackTrace() method does not return a String but is void and hence you cannot send it as a String argument to another method.

Is there a way to get its output as String object?

2. The second error is because the errorMsg() method throws an Exception which you do not handle. You should handle it in the catch clause again. Or include a throws Exception clause in the method declaration similar to one you have in errorMsg() method.

If I declare similar to my errorMsg() method then this method no need to write.

Is there any other solution?

Thanks for your favorable reply

[Jesper de Jong]

Interface Throwable has several printStackTrace() methods. The version without arguments prints the stack trace to System.err and does not allow you to get the stack trace in a string. There is however also a version that takes a PrintWriter, which you can use like this:

StringWriter sw = new StringWriter();
PrintWriter pw = new PrintWriter(sw);
e.printStackTrace(pw);

String stackTrace = sw.toString();

It's a bit cumbersome, but it works. There are some libraries that have utility methods to make it easier. For example, using Google Guava you could do:

String stackTrace = Throwables.getStackTraceAsString(e);

[Joanne Neal]

Jesper de Jong wrote:Interface Throwable has several printStackTrace() methods. The version without arguments prints the stack trace to System.err and does not allow you to get the stack trace in a string. There is however also a version that takes a PrintWriter, which you can use like this:

StringWriter sw = new StringWriter();
PrintWriter pw = new PrintWriter(sw);
e.printStackTrace(pw);

String stackTrace = sw.toString();

If you are going to do this, you should overload your errorMsg function to take an exception as a parameter and put this code in there, rather than converting the exception to a String every place you call errorMsg.

[Farakh khan]

Thanks all from the bottom of my heart for giving me your precious time.

I am still facing unreported exception java.lang.Exception; must be caught or declared to be thrown. I changed my method like this:

public static void errorMsg(String subject, Exception e) throws Exception{						

		StringWriter sw = new StringWriter();  
    		PrintWriter pw = new PrintWriter(sw);  
    		e.printStackTrace(pw);  
      
    		String stackTrace = sw.toString();  
		SendEmail.send("[e-mail]","[e-mail]",subject,msg); 		
	}

this block reporting exception:

} catch (Exception e) {	
	errorMsg("ERROR occured whilst un-zip file", e);
}

Thanks again & best regards

[Joanne Neal]

Farakh khan wrote:this block reporting exception:

} catch (Exception e) {	
	errorMsg("ERROR occured whilst un-zip file", e);
}

Your errorMsg method is defined to throw an Exception. You need to catch that exception or declare that the method that this code is in throws an Exception

[Farakh khan]

Thanks for your reply. I did like this:

} catch (Exception e) {
		try{
		errorMsg("ERROR occured whilst un-zip file", e);
		}catch(Exception ex){
		
		}

	}

and its working but I lost my objective to get the exception in my email. I mean even if this thrown some exception then this exception will not be passed to method and this will not be mailed to me because when am coding like:

} catch (Exception e) {
		try{
		errorMsg("ERROR occured whilst un-zip file", e);
		}catch(Exception ex){
		errorMsg("ERROR occured whilst un-zip file", e);
		}
	}

it again throws

thanks again

[Joanne Neal]

Farakh khan wrote:its working but I lost my objective to get the exception in my email

The most likely thing in your errorMsg method to throw an exception is SendEmail.send(). So by having a method that throws an exception if it can't send an email and catching that exception and trying to send another email is going to end up in an infinite loop. It would be better to catch any exception thrown by SendEmail.send in your errorMsg method and remove the throws clause.

[Jesper de Jong]

Farakh khan wrote:

} catch (Exception e) {
		try{
		errorMsg("ERROR occured whilst un-zip file", e);
		}catch(Exception ex){
		errorMsg("ERROR occured whilst un-zip file", e);
		}
	}

it again throws

Ofcourse, because the errorMsg in the nested catch block can still throw Exception, which you have to handle. You can do this recursively as far as you like...

catch (Exception e) {
    try {
        errorMsg("ERROR occured whilst un-zip file", e);
    } catch (Exception e2) {
        try {
            errorMsg("ERROR occured whilst un-zip file", e);
        } catch (Exception e3) {
            try {
                errorMsg("ERROR occured whilst un-zip file", e);
            } catch (Exception e4) {
                try {
                    errorMsg("ERROR occured whilst un-zip file", e);
                } catch (Exception e5) {
                    // This can still throw Exception which you are not handling!
                    // You can go on like this forever...
                    errorMsg("ERROR occured whilst un-zip file", e);
                }
            }
        }
    }
}

In my opinion, you should make errorMsg not throw Exception. Remove the "throws Exception" in the declaration of the errorMsg method, and handle exceptions that happen inside that method, inside the method itself (with a try-catch block). (Don't recursively call errorMsg() to handle them however!).

[Rob Spoor]

So change the errorMsg method to catch the exception instead of throwing it:

public static void errorMsg(String subject, Exception e)
{
    StringWriter sw = new StringWriter();  
    PrintWriter pw = new PrintWriter(sw);  
    e.printStackTrace(pw);  
      
    String stackTrace = sw.toString(); // you're not using this
    try
    {
        SendEmail.send("[e-mail]", "[e-mail]", subject, msg); // where did subject and msg come from?
    }
    catch (Exception ex)
    {
        // whatever you do, don't call errorMsg or you will get a recursive loop. Just log it somewhere
    }
}

[Joanne Neal]

Bit slow today Rob

[Farakh khan]

Finally I done like this:

} catch (Exception e) {
		try{
		errorMsg("ERROR occured whilst un-zip file", e);
		}catch(Exception ex){
		e.printStackTrace();
		}
	}

	return unzip;
	}//method


	public static void errorMsg(String subject, Exception e) throws Exception{						
		try{
			StringWriter sw = new StringWriter();  
	    		PrintWriter pw = new PrintWriter(sw);  
	    		e.printStackTrace(pw);        

    			String stackTrace = sw.toString(); 		 

			SendEmail.send("[e-mail]","[e-mail]",subject,stackTrace);

		}catch(Exception ex){
		errorMsg("ERROR in errorMsg()", ex);
		}
	}

I am grateful to all who extended their help

Thanks again & best regards

[Jesper de Jong]

Remove the "throws Exception" in line 13, so that you don't have to have a nested catch block and you can just do this:

catch (Exception e) {
    errorMsg("ERROR occured whilst un-zip file", e);
}

And don't call errorMsg recursively, as you are doing in line 24. You will get an infinite recursive loop when you do this, as Rob warned you for.

[Farakh khan]

That's all what I was looking for. Thanks again from the bottom of my heart

[Joanne Neal]

And more generally, always try to avoid throwing or catching Exception. Make the exception type as specific as possible. Especially as Java 7 allows you to do multiple catches in a single statement.

[Farakh khan]

Joanne Neal wrote:And more generally, always try to avoid throwing or catching Exception. Make the exception type as specific as possible. Especially as Java 7 allows you to do multiple catches in a single statement.

Thanks for addition