Question

我正在从网络中获取数据，并根据如下所示的响应创建了我的模型类：

{"batch_details":[{"batch_name":"batch ","batch_id":"49"},{"batch_name":"batch one","batch_id":"50"}],"status":1,"message":"success"}

我的活动有一个回收站视图，并且设置如下（仅响应部分）：

if (response != null) {
                        Log.d(TAG, "Batches Response:\t" + response.toString());
                        try {
                            JSONObject object = new JSONObject(response.toString());

                            message = object.getString("message");

                            JSONArray array = object.getJSONArray("batch_details");
                            for (int m = 0; m < array.length(); m++) {

                                JSONObject jsonObject = array.getJSONObject(m);

                                name_batch = jsonObject.getString("batch_name");
                                id_batch = jsonObject.getString("batch_id");

                                batch = new Batch();
                                batch.setBatchId(id_batch);
                                batch.setBatchName(name_batch);
                                batch.save();
                                Log.d(TAG, "BN local:\t" + batch.getBatchName() + "BN n/w:\t" + name_batch); //NW is from network that is jsonObj whereas local is from model getters

                                list.add(batch);

                                BatchFooter footer = new BatchFooter();
                                list.add(footer.getButton());

                                Log.d(TAG, "List size:\t" + list.size());

                                adapter = new BatchAdapter(ChooseBatchActivity.this, list);
                                adapter.setMessageValue(message);
                                batchRV.setAdapter(adapter);

在适配器的onBindViewHolder中，我试图从模型类中获取值并绑定到ui元素，如下所示：

 @Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
    if (holder instanceof BatchItemsViewHolder){
        BatchItemsViewHolder viewHolder = (BatchItemsViewHolder) holder;
        final Batch batch = (Batch) itemsList.get(position);
        viewHolder.batchNameTV.setText(batch.getBatchName());
    }
 }

但是抛出NPE：

java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String sportsapp.sashi.in.sportsapp.models.app.Batch.getBatchName()' on a null object reference
    at sportsapp.sashi.in.sportsapp.adapters.BatchAdapter.onBindViewHolder(BatchAdapter.java:60)
    at android.support.v7.widget.RecyclerView$Adapter.onBindViewHolder(RecyclerView.java:6673)
    at android.support.v7.widget.RecyclerView$Adapter.bindViewHolder(RecyclerView.java:6714)
    at android.support.v7.widget.RecyclerView$Recycler.tryBindViewHolderByDeadline(RecyclerView.java:5647)

有人可以帮助我了解为什么现在不起作用。我已经做过几次了，并且有效，问题仅在于模型类而不是recyclerview。谢谢。

我已经检查了batch.getBatchName()的值，您可以在记录它的行中看到，即使在设置了响应值后，它仍然为null。这说明了NPE，但没有解决方法。

设置值后，模型类的获取方法返回空值

0 个答案: