Question

My Activity holds a member member_one which holds another member member_two which can throw an Exception. I need to show user a Toast if this Exception happens. In order to show a Toast I need to throw Exception from member_tow to member_one and then from member_one to my Activity. This approach leads to big changes and I don’t want to do so. May be I just think wrong, is there any easy way to handle the exception?

Answer 1

So far I know there will be two solutions of the problem.

• pass Context to you member_one, member_two and then use that Context to make Toast. Like Toast.makeText(mContext, "Exception Occurred", Toast.LENGTH_SHORT).show();

Second approach will be through Interface

-Make a Interface method in your class of member_one and so on

like

public interface OnErrorOccured {
        public void whatIsErr(String msg);
    }

    OnErrorOccured onError;

    public void setOnDetailsLoadListener(OnErrorOccured onError) {
        this.onError = onError;
    }
`

and when ever you getException call onError.whatIsErr(e.toString());

and in main Activity

 member_one.setOnErrorListener(mErrorOccured);

 OnErrorOccured mErrorOccured =new OnErrorOccured() {

    @Override
    public void whatIsErr(String msg) {
        // Do what ever you want..show Toast, or do any UI update

    }
};

How other programmers know if they want to use one of these classes they need to set listeners?

Well for this you force the constructor to pass a listener.

Like

public yourConstructor(OnErrorOccured errorListener,.....)
{
   this.setOnErrorListener(errorListener);
   ...

}