如何在从另一个 activity android 返回时更新列表视图？

Question

你好如何在按下另一个 activity 时更新 listView。我正在使用数据库，我正在其中删除一个 Activity 中的特定行，如果单独按下，它不会更新。当我切换到其他 activity 或应用程序关闭并打开时它工作正常 listView 得到更新。

这是代码..

public class FragmentLiveChats extends Fragment {
    private AdapterLiveChat adapterChatHistory;
    private List<LiveChatDetails> customerDetail;
    private ListView mListView;
       private List<LiveChatDetails> list;
@Override
public void onViewCreated(View view, Bundle savedInstanceState) {  
list =AAEDatabaseHelper.getLiveChatDetails(Constants.TABLE_LIVE_CHAT);   
    mListView = (ListView)   rootView.findViewById(R.id.list_chat_history);
      parseResponse();
}

private void parseResponse(){
 for(int i=0;i<list.size();i++){
        LiveChatDetails chatDetailsList = new LiveChatDetails();
        chatDetailsList.setId(list.get(i).getId());
       chatDetailsList.setFromUsername(list.get(i).getFromUsername());
        chatDetailsList.setChatTime(list.get(i).getChatTime());
        chatDetailsList.setLatMsg(list.get(i).getLatMsg());
        customerDetail.add(chatDetailsList);
    }
    setValuesInAdapter();
 }
 @Override
public void onResume() {
    // TODO Auto-generated method stub
    super.onResume();
    adapterChatHistory.updateList(customerDetail);
    adapterChatHistory.notifyDataSetChanged();
}

private void setValuesInAdapter() {
    if (adapterChatHistory == null) {
        adapterChatHistory = new AdapterLiveChat(context);
    }
    adapterChatHistory.setExpertData(customerDetail);
    if (customerDetail != null && !customerDetail.isEmpty()) {
        mListView.setVisibility(View.VISIBLE);
        viewNoData.setVisibility(View.GONE);
        mListView.setAdapter(adapterChatHistory);
    } else {
        mListView.setVisibility(View.GONE);
        viewNoData.setVisibility(View.VISIBLE);
    }
    adapterChatHistory.notifyDataSetChanged();
    mListView.setOnItemClickListener(new OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> parent, View view,
                int position, long id) {
            LiveChatDetails chatDetails = (LiveChatDetails) parent.getAdapter()
                                                .getItem(position);
            Log.e("chatDetails", "chat details"+chatDetails.getId());
            Intent intent = new Intent(context,ActivityExpertChatView.class);
            intent.putExtra(Constants.CHAT_USER_NAME, chatDetails.getId());
            startActivity(intent);
        }
    });
}

在适配器中：

public void setExpertData(List<LiveChatDetails> mTempData) {
    this.mTempData = mTempData;
}

在 ExpertChatView activity 中，我正在删除一条记录，如果我来到这个屏幕，即通过向后按之前的 activity，它仍然保持相同的列表并且它是不更新。但是当我关闭应用程序并打开时，它工作正常。

在 expertChatView activity 中，我正在删除用户名记录。

AAEDatabaseHelper.deleteUsername(<username>);

我尝试在 onResume() 中使用 notifyDatasetChanged 方法，但仍然是同样的问题。

编辑

 Adapter class 

public class AdapterLiveChat extends BaseAdapter {
private Context context;
private List<LiveChatDetails> mTempData;
private LayoutInflater mInflater;
private LiveChatDetails liveChatDetails;

private View adView;
private ViewHolder holder;

private String userImageUrl;


public AdapterLiveChat(Context context) {
    this.context = context;
    imgLoader = Picasso.with(context);
    mCalendar = Calendar.getInstance();
}

public void setExpertData(List<LiveChatDetails> mTempData) {
    this.mTempData = mTempData;
}

public void updateList(List<LiveChatDetails> mChatDetails) {
    this.mTempData = mChatDetails;
}

@Override
public int getCount() {
    return mTempData.size();
}

@Override
public LiveChatDetails getItem(int position) {
    return mTempData.get(position);
}

@Override
public long getItemId(int position) {
    return position;
}
 @Override
 public View getView(int position, View convertView, ViewGroup parent)                      {
    mInflater = (LayoutInflater) context
            .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    liveChatDetails = getItem(position);
    adView = convertView;
    if (adView == null) {
        holder = new ViewHolder();
        adView = mInflater.inflate(R.layout.row_live_chats, null);
        holder.txtName = (CustomTextView) adView
                .findViewById(R.id.txt_name);
     adView.setTag(holder);
    } else
        holder = (ViewHolder) adView.getTag();
    holder.txtName.setText(liveChatDetails.getFromUsername());
   return adView;
   }

// 查看持有人 class 这里...

Answer 1

从 customerDetail 列表中删除该项目，然后调用 notifydatasetchanged()

Answer 2

首先在Adapter中写下方法

    public void updateList(List<Messages> mChatDetails) {
    this.mChatDetails.clear();
    this.mChatDetails.addAll(mChatDetails)
}

在恢复中从数据库中获取数据并调用 updateList(List mChatDetails) 方法，然后调用 notifyDatasetChanged()

    @Override
public void onResume() {
    // fetch updated data
    adapter.updateList(mChatDetails);
    adapter.notifyDataSetChanged();
}

Answer 3

在活动 1 中调用 finish()

Intent intent = new Intent(getApplicationContext(), Activity2.class);
startActivity(intent);
finish();

在活动 2 中覆盖返回按下

public void onBackPressed(){
    Intent i = new Intent(this,AdminActivity.class);
    startActivity(i);
}

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