使用 try/catch 声明和初始化最终变量

Question

我正在尝试在适配器中声明和初始化最终变量，以便在 OnLongClickListener() 声明中使用该变量。问题是该变量正在由可能引发失败异常的方法初始化，因此初始化必须在 try/catch 的上下文中进行。在异常块中，有一个最终变量被分配给的后备值。这一切都发生在ArrayAdapter<T> 的覆盖getView() 内。

我的问题是，有没有一种巧妙的方法可以做到这一点？我通过在 try/catch 之外声明一个临时变量，并在 try/catch 中对其进行初始化，然后在 try/catch 块之后使用临时变量的结果声明和初始化最终变量来解决这个问题。这感觉太乱了。

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?

代码：

@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

可以将逻辑移动到 Vehicle 自己的方法中。它使其可重复使用且更易于阅读。

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);
    }
}

然后回到原来的方法：

final Vehicle vehicle = getVehicle(position);