如何在列表视图中保存二维码扫描结果?

Question

在条形码部分，我读取了条形码。我想将扫描结果保存到我创建的列表视图中。我试图通过查看许多项目来做到这一点，但我失败了。你可以帮我吗？如果这个问题有点长，我很抱歉。

public class BarcodeReaderFragment extends Fragment {
barcodeDetector.setProcessor(new Detector.Processor<Barcode>() {
@Override
public void release() {
}
@Override
public void receiveDetections(Detector.Detections<Barcode> detections) {
final SparseArray<Barcode> qrcode = detections.getDetectedItems();
if (qrcode.size() != 0) {
Intent my = new Intent(getActivity(),ResultActivity.class);
my.putExtra("type", qrcode.valueAt(0));
currentTime = Calendar.getInstance().getTime();
df = new SimpleDateFormat("dd-MMM-yyyy");
String formattedDate = df.format(currentTime);
String d = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(Calendar.getInstance().getTime());
System.out.println(formattedDate);
//Add QR scan result to listview???
//Add current time and date to listview???
Gson gson = new Gson();
String json = gson.toJson(qrcode.valueAt(0));
SharedPreferences sp = getActivity().getSharedPreferences("list",Context.MODE_PRIVATE);
addhistory(sp,json);
startActivity(my);
getActivity().finish();
barcodeDetector.release();
}
}
});
public void addhistory(SharedPreferences sp,String json){
int x = sp.getInt("index",0);
SharedPreferences.Editor editor = sp.edit();
editor.putString(String.valueOf(x),json);
int  y;
y = x+1;
editor.putInt("index",y);
editor.commit();
}

Item_Model

public class Item_Model implements Serializable {
private String result, date_time;
public Item_Model(String result, String date_time) {
this.result = result;
this.date_time = date_time;
}
public String getResult() {
return result;
}
public String getDate_time() {
return date_time;
}

ListView_Adapter

public class ListView_Adapter extends BaseAdapter {
private Context context;
private ArrayList<Item_Model> item_modelArrayList;
private SparseBooleanArray mSelectedItemsIds;
public ListView_Adapter(Context context, ArrayList<Item_Model> item_modelArrayList) {
this.context = context;
this.item_modelArrayList = item_modelArrayList;
mSelectedItemsIds = new SparseBooleanArray();
}
@Override
public int getCount() {
return item_modelArrayList.size();
}
@Override
public Item_Model getItem(int position) {
return item_modelArrayList.get(position);
}
@Override
public long getItemId(int position) {
return position;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
ViewHolder holder;
if (convertView == null) {
convertView = inflater.inflate(R.layout.item_row, parent, false);
holder = new ViewHolder();
holder.Result = (TextView) convertView.findViewById(R.id.result);
holder.Date_time = (TextView) convertView.findViewById(R.id.date_time);
convertView.setTag(holder);
} else
holder = (ViewHolder) convertView.getTag();
holder.Result.setText(item_modelArrayList.get(position).getResult());
holder.Date_time.setText(item_modelArrayList.get(position).getDate_time());

/** Change background color of the selected items in list view  **/
convertView
.setBackgroundColor(mSelectedItemsIds.get(position) ? 0x48FF9800
: Color.TRANSPARENT);
return convertView;
}
private class ViewHolder {
TextView Result, Date_time;
}

三片段在这一集中，我正在看Listview。

private ActionMode mActionMode;
private static View view;
private static ListView_Adapter adapter;
private static ListView listView;
//Action Mode for toolbar
private static ArrayList<Item_Model> item_models;
public ThreeFragment() {
}
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
view = inflater.inflate(R.layout.fragment_three, container, false);
populateListView();
implementListViewClickListeners();


return view;
}


//I don't know how to fill this section with detector results?
//Populate ListView with dummy data
private void populateListView() {
listView = (ListView) view.findViewById(R.id.list_view);
item_models = new ArrayList<>();
for (int i = 1; i <= 40; i++)
item_models.add(new Item_Model("Result " + i, "Date-Time " + i));

adapter = new ListView_Adapter(getActivity(), item_models);
listView.setAdapter(adapter);
adapter.notifyDataSetChanged();
}

//Implement item click and long click over listview
private void implementListViewClickListeners() {
listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
//If ActionMode not null select item
if (mActionMode != null)
onListItemSelect(position);
}
});
listView.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() {
@Override
public boolean onItemLongClick(AdapterView<?> parent, View view, int position, long id) {
//Select item on long click
onListItemSelect(position);
return true;
}
});
}
//List item select method
private void onListItemSelect(int position) {
adapter.toggleSelection(position);//Toggle the selection
boolean hasCheckedItems = adapter.getSelectedCount() > 0;//Check if any items are already selected or not
if (hasCheckedItems && mActionMode == null)
// there are some selected items, start the actionMode
mActionMode = ((AppCompatActivity) getActivity()).startSupportActionMode(new Toolbar_ActionMode_Callback(getActivity(),adapter, item_models, true));
else if (!hasCheckedItems && mActionMode != null)
// there no selected items, finish the actionMode
mActionMode.finish();
if (mActionMode != null)
//set action mode title on item selection
mActionMode.setTitle(String.valueOf(adapter
.getSelectedCount()) + " selected");

}
//Set action mode null after use
public void setNullToActionMode() {
if (mActionMode != null)
mActionMode = null;
}

//Delete selected rows
public void deleteRows() {
SparseBooleanArray selected = adapter
.getSelectedIds();//Get selected ids
//Loop all selected ids
for (int i = (selected.size() - 1); i >= 0; i--) {
if (selected.valueAt(i)) {
//If current id is selected remove the item via key
item_models.remove(selected.keyAt(i));
adapter.notifyDataSetChanged();//notify adapter
}
}
Toast.makeText(getActivity(), selected.size() + " item deleted.", Toast.LENGTH_SHORT).show();//Show Toast
mActionMode.finish();//Finish action mode after use
}

Answer 1

尝试通过以下步骤实现：

1. 将ResultActivity保留为登陆/父活动。
2. 向ResultActivity添加ThreeFragment
3. 创建BarcodeReaderActivity并直接在此活动中使用BarcodeDetector(为简单起见，删除BarcodeReaderFragment(
4. 从ThreeFragmentstartActivityForResult()开始BarcodeReaderActivity您喜欢的互动。
5. 何时从BarcodeDetector获得结果，然后使用setResult("xxxxxx")将结果设置为BarcodeReaderActivity并finish()活动。
6. 在ThreeFragment，您将获得onActivityResult()的结果
7. 得到结果后，将其放入list并将列表发送给Adapter并notifyDataSetChanged()。

更新

很抱歉，我无法更改整个项目导航，这对我来说会花费太多时间。你应该在这里问一个准确的问题。我刚刚检查了您的项目并在下面提供了一些反馈。您必须自己为此编写代码。

1. 使用数据库作为数据列表(QR 扫描结果(
2. 对于ViewPager，您可以通过以下代码找到片段的visibility/invisibility：

@Override
public void setUserVisibleHint(boolean isVisibleToUser) {
super.setUserVisibleHint(isVisibleToUser);
if (isVisibleToUser && isResumed()) {
//this fragment is visible now, do your expected code here
} else {
//this fragment is not visible now, do your expected code here
}
}
@Override
public void onResume() {
super.onResume();
if(getUserVisibleHint()){
//this fragment is visible now, do your expected code here
} else {
//this fragment is not visible now, do your expected code here
}
}

建议：尝试逐步实施，如果出现任何问题，请尝试先解决具体问题。