Question

I am writing data to a file, when I write this data I want to do it so that if the file does not open it will give the user a message saying that something whent wrong. The way I do this is by calling the method to write, if it fails it returns false. That way I can prompt the user to do something to check what has happened.

However when I create the object I cant return anything from the constructor so I am a bit stumped about what I should do.

public class Writetofile {
BufferedWriter writer = null;

public Writetofile(String[]details) throws IOException{
String machine= details[0];
String date=details[1];
String start_time = details[2];     
try{
   File new_cal= new File("C:\\Activity_Calibrator\\log\\"+machine+"\\"+machine+date+".txt");
   new_cal.getParentFile().mkdir();
   FileWriter fwriter = new FileWriter(new_cal);
   writer = new BufferedWriter(fwriter); 
   writer.write("Linear Calibratiton for " + machine + " carried out " + date+" ./n");
   writer.close();
  }
catch(Exception e){ in here I would like to be able to send a message back to m
code so that it can tell the user to check the folder etc}
} 

when I call the record data if something goes wrong it will return a false to the calling class. and I can put a message.

 public boolean recordData(String record) throws IOException{
try{
    writer.append(record);
    writer.close();
    return true;
   }
catch(Exception e){
    return false;

   }
 }
 }
 } 

Answer 1

A constructor should not DO anything. A constructor is an initialization phase closely tied to the allocation of an object.

Throwing exceptions, or doing anything in a constructor that might throw an exception is to be avoided.

Java does not separate the phases of allocation and initialization, no code, especially IO code should be in a constructor.