Avoid same try catch blocks in Java

Question

I am developing a project which involves JSON manipulation in Java using JSON API. There are many places where I need to read values from JSON file. The API provides checked exceptions for the same. Everytime I use the API to read JSON values, I am forced to write try catch block. As a result, there is a large number of try catch blocks. It makes the code look messy.

    String Content = "";
    try {
        read = new BufferedReader(new FileReader("Data.json"));
    }
    catch(Exception e) {
        System.out.println("File Not found");
    }

    try {
        while((line = read.readLine() ) != null) { 
            Content = Content+line;     
        }
    } catch (IOException e) {
        e.printStackTrace();
    }
    try {
        ResponseArr = new JSONArray( Content );
    } catch (JSONException e) {
        e.printStackTrace();
    }
    try {
        ResponseObj = ResponseArr.getJSONObject(1).getJSONArray("childrens");

    } catch (JSONException e) {
        e.printStackTrace();
    }
    try {
        StoreResponse = ResponseArr.getJSONObject(0).getJSONArray("childrens");

    } catch (JSONException e) {
        e.printStackTrace();
    }

Is there any way to avoid this ?A single try catch block would not suffice and the statements are not dependent. Each read statement requires a separate try catch block as I have to log the details of places while catching the exception. Can I invoke a common method whenever I have a code to read JSON data, like sending the code as a paramater to a method which would take care of the exception handling or some other way round ?

You could also have one big try/catch block with everything inside. — Thilo
– Thilo, Commented Oct 28, 2015 at 7:20
You should not have separate try/catch like this... Anyway if your first try fails, all the others are bound to fail too since read would be null... — Codebender
– Codebender, Commented Oct 28, 2015 at 7:20

Fontanka16 · Accepted Answer · 2015-10-28 07:37:31Z

1

Since (all?) the subsequent statements are dependent on the previous it makes no sense having that many try/catch blocks. I would rather put the code inside one try/catch and handle the exceptions by type

Pseudo-code:

 String Content = "";
    try {
        read = new BufferedReader(new FileReader("Data.json"));
        while((line = read.readLine() ) != null) { 
            Content = Content+line;     
        }
        ResponseArr = new JSONArray( Content );
        ResponseObj = ResponseArr.getJSONObject(1).getJSONArray("childrens");
    } catch (JSONException e) {       
        e.printStackTrace();    
    } catch(FileNotFoundException)
            System.out.println("File Not found");
    }
    // and so on

As some are suggesting, you might want to let all these exceptions bubble up (not catching them) since you're not doing anything meaningful when catching them. However, I think that depends on the calling context.

edited Oct 28, 2015 at 7:37

answered Oct 28, 2015 at 7:22

Fontanka16

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9 Comments

TheLostMind Over a year ago

I would rather have separate catch blocks. Don't rely on instanceOf, it can cause chaos in case of inheritance

ug_ Over a year ago

The premise is correct but your catch statement is no good, before I downvote I would like to give you the opportunity to fix it. You should catch those in their own catch block.

Thilo Over a year ago

@VinodMadyalkar: Well, inheritence will work just the same way in multiple catch blocks.

TheLostMind Over a year ago

@Thilo - Right. I was just making a general note about not relying in instanceOf too much in situations like this. Of course if the ordering of catch blocks is wrong, the OP will get an Unreachable code compiler error :)

Thilo Over a year ago

I am with @ug_, don't catch these exceptions at all, let them bubble up. Only catch exceptions when you can really do something about them.

|

Dev.H · Accepted Answer · 2015-10-28 07:24:41Z

0

If you are handling all exceptions in the same way, why not combine them in one try/ catch clause for example like this :

try {
        while((line = read.readLine() ) != null) { 
            Content = Content+line;     
        }
       ResponseArr = new JSONArray( Content );
       ResponseObj = ResponseArr.getJSONObject(1).getJSONArray("childrens");
    } catch (Exception e) {
        e.printStackTrace();
    }

answered Oct 28, 2015 at 7:24

Dev.H

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2 Comments

Thilo Over a year ago

and that also allows you to declare content and responseArr locally inside that scope.

mschenk74 Over a year ago

catch (Exception e) is not a good idea in the most cases. Try to be more specific since your statement will also catch RuntimeExceptions

Abdul Manaf · Accepted Answer · 2015-10-28 07:31:35Z

0

Try like this

String Content = "";
try {
    read = new BufferedReader(new FileReader("Data.json"));
       while((line = read.readLine() ) != null) { 
        Content = Content+line;     
      }
      ResponseArr = new JSONArray( Content );
      ResponseObj = ResponseArr.getJSONObject(1).getJSONArray("childrens");
    } 
    catch (IOException e) {
      e.printStackTrace();
    }
    catch (JSONException e) {
      e.printStackTrace();
    }
    catch(Exception e) {
      System.out.println("File Not found");
    }

answered Oct 28, 2015 at 7:31

Abdul Manaf

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