使用try / catch声明并初始化最终变量

Question

I'm trying to declare and initialize a final variable in an adapter in order to use the variable in an OnLongClickListener() declaration. The problem is that the variable is being initialized by a method that can potentially throw a failure exception, so the initialization must happen in the context of a try/catch. In the exception block, there is a fallback value that the final variable is assigned to instead. This all happens within the overridden getView() of the ArrayAdapter<T> .

My question is, is there a slick way to do this? I've gotten around this by just declaring a temporary variable outside the try/catch, and initializing it in the try/catch, then declaring and initializing the final variable after the try/catch block with the results of the temporary variable. This just feels too messy.

This question is pretty closely related, but the solution presented seems extreme. Is it typical to wrap the entire contents of a method in a try/catch?

Code:

@Override
public View getView(final int position, View convertView, ViewGroup parent) {
        LayoutInflater inflater = (LayoutInflater) Data.getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);

//begin eww gross
        Vehicle temp;
        try {
            temp = Data.getVehicle(values.get(position).getId());
        } catch (ObjectNotFoundException e) {
            Log.e(TAG, e.getMessage() + "-- unable to find vehicle while getting list item vehicle for vehicles tab fragment");
            temp = values.get(position);
        }
        final Vehicle vehicle = temp;
//end disappointing, ugly workaround

        ViewHolder holder;
        if (convertView == null) {
            convertView = inflater.inflate(R.layout.vehicle_item_with_img, null);
            holder = new ViewHolder();
            holder.vehicleLabel = (TextView) convertView.findViewById(R.id.vehicle_label);
            holder.statusImage = (ImageView) convertView.findViewById(R.id.lmImageView);
            holder.sImage = (ImageView) convertView.findViewById(R.id.sImageView);
            holder.vehicleTag = vehicle.getId();
            convertView.setTag(holder);
        } else {
            holder = (ViewHolder) convertView.getTag();
        }


        if (Data.isFollowingVehicle(vehicle)) {
            holder.sImage.setVisibility(View.VISIBLE);
        }
        else {
            holder.sImage.setVisibility(View.INVISIBLE);
        }

        holder.statusImage.setImageDrawable(vehicle.getListIcon());
        holder.vehicleLabel.setText(vehicle.getFormattedLabel());

        final ViewHolder finalHolder = holder;
        convertView.setOnLongClickListener(new View.OnLongClickListener() {
            @Override
            public boolean onLongClick(View v) {
                if (!vehicle.isFollowed()) {
                    finalHolder.sImage.setVisibility(View.VISIBLE);
                    mapInterface.follow(vehicle);
                } else {
                    finalHolder.sImage.setVisibility(View.GONE);
                    mapInterface.unfollow(vehicle);
                }
                return false;
            }
        });

        convertView.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                mapInterface.handleVehicleClickFromList(vehicle);
            }
        });

        return convertView;
    }

Answer 1

It is fine to move the logic to get the Vehicle into its own method. It makes it reusable and easier to read.

private Vehicle getVehicle(int position) {
    try {
        return Data.getVehicle(values.get(position).getId());
    } catch (ObjectNotFoundException e) {
        Log.e(TAG, e.getMessage() + "-- unable to find vehicle while getting list item vehicle for vehicles tab fragment");
        return values.get(position);
    }
}

and then back in your original method:

final Vehicle vehicle = getVehicle(position);