CoverFlow 不显示图像

Question

我正在使用 coverflow 来显示我的图像，但是当我运行我的项目崩溃并给出以下错误时。任何人都可以帮助我吗？以下是我的代码片段有什么帮助会被应用

: FATAL EXCEPTION: main Process: com.example.daysheft.dpc, PID: 21087 java.lang.NullPointerException: Attempt to invoke interface method 'int android.widget.Adapter.getCount()' on a null object reference at it.moondroid.coverflow.components.ui.containers.FeatureCoverFlow.dispatchDraw(FeatureCoverFlow.java:471) at android.view.View.updateDisplayListIfDirty(View.java:15185) at android.view.View.draw(View.java:15964)

CoverflowActivity.java

public class CoverFlowActivity extends ActionBarActivity {

    private FeatureCoverFlow mCoverFlow;
    private CoverFlowAdapter mAdapter;
  //  private ArrayList<GameEntity> mData = new ArrayList<>(0);
    private TextSwitcher mTitle;
    private String productlanding_url;
    private String ProductID;

    private ProgressDialog pDialog;
    private ArrayList<PackListModel> categorylist;
    private ArrayList<PackSizeModel> subcat_list;
    private PackListModel cm;



    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_coverflow);

         ProductID=getIntent().getStringExtra("Product_Id");

        productlanding_url=Globaldata.APP_URL+"ProductLanding";
        pDialog = new ProgressDialog(this);
        // Showing progress dialog before making http request
        pDialog.setMessage("Loading...");
        pDialog.show();

        GetProductLanding();

       /* mData.add(new GameEntity(R.drawable.tesss, R.string.title1));
        mData.add(new GameEntity(R.drawable.tesss, R.string.title2));
        mData.add(new GameEntity(R.drawable.tesss, R.string.title3));
        mData.add(new GameEntity(R.drawable.tesss, R.string.title4));*/

       /* mTitle = (TextSwitcher) findViewById(R.id.title);
        mTitle.setFactory(new ViewSwitcher.ViewFactory() {
            @Override
            public View makeView() {
                LayoutInflater inflater = LayoutInflater.from(CoverFlowActivity.this);
                TextView textView = (TextView) inflater.inflate(R.layout.item_title, null);
                return textView;
            }
        });
        Animation in = AnimationUtils.loadAnimation(this, R.anim.slide_in_top);
        Animation out = AnimationUtils.loadAnimation(this, R.anim.slide_out_bottom);
        mTitle.setInAnimation(in);
        mTitle.setOutAnimation(out);
*/
        /*mAdapter = new CoverFlowAdapter(CoverFlowActivity.this,categorylist);
        mAdapter.setData(categorylist);*/
        mCoverFlow = (FeatureCoverFlow) findViewById(R.id.coverflow);
     //   mCoverFlow.setAdapter(mAdapter);

        mCoverFlow.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
              /*  Toast.makeText(CoverFlowActivity.this,
                        getResources().getString(mData.get(position).titleResId),
                        Toast.LENGTH_SHORT).show();*/
            }
        });

        mCoverFlow.setOnScrollPositionListener(new FeatureCoverFlow.OnScrollPositionListener() {
            @Override
            public void onScrolledToPosition(int position) {
               // mTitle.setText(getResources().getString(mData.get(position).titleResId));
            }

            @Override
            public void onScrolling() {
                //mTitle.setText("");
            }
        });

    }

    public void GetProductLanding()
    {

        showpDialog();

        Map<String, String> params = new HashMap<String, String>();
        params.put("productId", "1004");
        params.put("userID", "1");

        System.out.println("PARAMS ProductLanding" + params);
        JsonArrayRequest request = new JsonArrayRequest(Request.Method.POST, productlanding_url, new JSONObject(params),
                new Response.Listener<JSONArray>() {
                    @Override
                    public void onResponse(JSONArray response) {
                        System.out.println("response of ProductLanding" + response.toString());

                       try {

                            for (int i = 0; i < response.length(); i++) {

                                JSONObject person = (JSONObject) response
                                        .get(i);
                                JSONArray itemlist=person.optJSONArray("itemList");
                                System.out.println("ProductLanding itemlist"+itemlist);

                               for(int j=0;j<itemlist.length();j++)
                                {
                                    JSONObject itmobj = (JSONObject)itemlist
                                            .get(j);


                                    JSONArray typemasters=itmobj.optJSONArray("packInfo");

                                   categorylist=new ArrayList<PackListModel>();

                                    for(int k=0;k<typemasters.length();k++)
                                    {

                                        subcat_list = new ArrayList<PackSizeModel>();
                                        JSONObject typemasterobj=(JSONObject)typemasters.get(k);
                                        cm=new PackListModel();
                                        cm.setProductLanding_packId(typemasterobj.getString("packId"));
                                        cm.setProductLanding_packLink(typemasterobj.getString("packDesc"));
                                        cm.setProductLanding_packDesc(typemasterobj.getString("packLink"));


                                        if (typemasterobj.getString("packSizeDetails").equals("null")) {
                                            System.out.println("arr null");
                                        } else {
                                            JSONArray SubcategoryArr = typemasterobj.optJSONArray("packSizeDetails");

                                            for (int l = 0; l < SubcategoryArr.length(); l++) {

                                                JSONObject Subcategoryobj = SubcategoryArr.getJSONObject(l);
                                                String packQty = Subcategoryobj.getString("packQty");
                                                String packSize = Subcategoryobj.getString("packSize");
                                                String sellingPrice = Subcategoryobj.getString("sellingPrice");
                                                String lineThroughPrice = Subcategoryobj.getString("lineThroughPrice");
                                                String packSizePrice = Subcategoryobj.getString("packSizePrice");
                                                String freeShipping = Subcategoryobj.getString("freeShipping");
                                                String reOrderPrice = Subcategoryobj.getString("reOrderPrice");
                                                PackSizeModel ch = new PackSizeModel();
                                                ch.setPackSize_packQty(packQty);
                                                ch.setPackSize_packSize(packSize);
                                                ch.setPackSize_sellingPrice(sellingPrice);
                                                ch.setPackSize_lineThroughPrice(lineThroughPrice);
                                                ch.setPackSize_packSizePrice(packSizePrice);
                                                ch.setPackSize_freeShipping(freeShipping);
                                                ch.setPackSize_reOrderPrice(reOrderPrice);
                                                // ch.setChild_Id(jo.getString("categoryID"));
                                                subcat_list.add(ch);
                                            } // for loop end

                                            cm.setItems(subcat_list);


                                        }

                                        categorylist.add(cm);

                                    }

                                    System.out.println("SIZE"+categorylist.size());
                                   /* mAdapter = new CoverFlowAdapter(CoverFlowActivity.this,categorylist);
                                    mAdapter.setData(categorylist);
                                    mCoverFlow.setAdapter(mAdapter);*/
                                }

                            }


                        } catch (JSONException e) {
                            e.printStackTrace();
                            System.out.println("Error" + e.getMessage());
                            // Toast.makeText(getApplicationContext(), "Error: " + e.getMessage(), Toast.LENGTH_LONG).show();
                        }

                        hidepDialog();
                    }
                },
                new Response.ErrorListener() {
                    @Override
                    public void onErrorResponse(VolleyError error) {
                        System.out.println("change Pass response -->> " + error.toString());
                        hidepDialog();
                    }
                });

        request.setRetryPolicy(new

                DefaultRetryPolicy(60000,
                DefaultRetryPolicy.DEFAULT_MAX_RETRIES,
                DefaultRetryPolicy.DEFAULT_BACKOFF_MULT));


        Volley.newRequestQueue(CoverFlowActivity.this).add(request);
    }


    private void showpDialog() {
        if (!pDialog.isShowing())
            pDialog.show();
    }

    private void hidepDialog() {
        if (pDialog.isShowing())
            pDialog.dismiss();
    }


}

Answer 1

您的 categorylist 必须有值才能将其设置为 mAdapter。要克服此错误，请初始化您的 mAdapter 以响应您的截击请求。如果 this 库适合您的应用程序，请使用更好的解决方案。

CoverFlow 不显示图像

CoverFlow not displaying image

android

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android-layout

baseadapter