Question

我有一系列图像，当用户按下时应启动一个新活动并传递一些数据（自定义对象的ArrayList）。自定义对象的ArrayList根据用户输入进行初始化。现在，我面临的问题是，当用户尚未为ArrayList提供输入并单击任何Image时，它会显示应用程序停止。我尝试通过try和catch块来处理它，但它不起作用。当ArrayList不为空时，整个流程工作正常。Image to have look at App (on Top, series of images are there which gets populated basis user selection from a list and then user can click any image of them)

查找以下相关代码：

MainActivity的相关阻止：

 @Override
        public void onBindViewHolder(final MyViewHolder holder, final int position) {

            holder.imageView.setImageResource(horizontalList.get(position).imageId);
            holder.txtview.setText(horizontalList.get(position).txt);

            holder.imageView.setOnClickListener(new View.OnClickListener() {
                @Override

                public void onClick(View v) {


                    String list = horizontalList.get(position).txt.toString();
                    List<Coupon> couponList = new ArrayList<>();
                    try {
                        for (Place place : allOffers) {
                            Coupon coupon = new Coupon(place.mPlace, place.mOffer, place.mImage, list);
                            couponList.add(coupon);
                        }

                        Toast.makeText(MainActivity.this, list, Toast.LENGTH_SHORT).show();
                        Intent intentCat = new Intent(MainActivity.this, CategoryOffersActivity.class);
                        intentCat.putExtra("Category", (Serializable) couponList);
                        startActivity(intentCat);

                    } catch(Exception e) {
                        Toast.makeText(MainActivity.this,"List is Empty",Toast.LENGTH_SHORT).show();
                        }
                }

            });

        }

用户点击图片时启动的新活动：

public class CategoryOffersActivity extends AppCompatActivity implements PlaceAdapter.AdapterInterface,Serializable {

    ListView catListView;
    List<Place> catOffers = new ArrayList<Place>();
    PlaceAdapter catPlaceAdapter;
    Place [] catPlaces;
    List <Coupon> listCoupon=new ArrayList<Coupon>();
    TextView mHeader;


    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_categoryoffers);
        catListView = (ListView) findViewById(R.id.catListView);
        mHeader=(TextView)findViewById(R.id.categoryName);

        if (getIntent() != null) {
            listCoupon = (ArrayList<Coupon>) getIntent().getSerializableExtra("Category");
            if (listCoupon != null) {
                ArrayList<Place> placeList = new ArrayList<>();
                for(Coupon coupon : listCoupon) {
                    Place place=new Place(coupon.mPlace,coupon.mOffer,coupon.mImage);
                    placeList.add(place);
                }
                catPlaces=placeList.toArray(new Place[placeList.size()]);
                mHeader.setText(listCoupon.get(0).mItemClicked+" Coupon History");
                catPlaceAdapter = new PlaceAdapter(CategoryOffersActivity.this, R.layout.row, catPlaces, this);
                if (catListView != null) {
                    catListView.setAdapter(catPlaceAdapter);
                }

            }
        }


    }





    @Override
    public void buttonPressed() {
        // some action
    }

}

Answer 1

if ((listCoupon != null)&&(listCoupon.size()>0))

同时检查数组大小

如何在启动另一个活动时处理null ArrayList

1 个答案: