How to resolve Improper Resource Shutdown or Release issue

Question

I submitted my code for Veraocode Security Testing tool and i got this Improper Resource Shutdown or Release at the below code:

//This function is used to print trace in the in the LogFile for debugging purpose  
PrintWriter f;  
            try {  
                f = new PrintWriter(new BufferedWriter(new FileWriter(fileName,true)));//issue at this line  
                synchronized(this) {  
                    f.println(new StringBuffer(dateString).append("<").append(Thread.currentThread().getName()).append(">").append(traceLog).toString());  
                }  
                f.close();  
                checkFileSize();  
            }catch(IOException e){    
                e.printStackTrace();  
            }   

Someone please help me on this...

Answer 1

You need to close your PrintWriter.

f.close();

Answer 2

     try {  
            f = new PrintWriter(new BufferedWriter(new FileWriter(fileName,true)));//issue at this line  
            synchronized(this) {  
                f.println(new StringBuffer(dateString).append("<").append(Thread.currentThread().getName()).append(">").append(traceLog).toString());  
            }  

            checkFileSize();  
        }catch(IOException e){    
            e.printStackTrace();  
        } finally {
             if (f != null) {
                 f.close();
             }
        }

Resources should be closed in finally clause. So that they definitely get executed. Because if you put closing code in try, and some exception occurs before the closing line. The resource doesn't get closed properly.

Also if you are using JDK-7, have a look at try-with-resources.

Answer 3

You need to close the PrintWriter in catch block also Or create finally block and close the resource.

}catch(IOException e){    
e.printStackTrace();
f.close();
}

OR

finally {
if (f != null) {
f.close();
}
}