【问题标题】：getActivity() inside viewholder视图中的getActivity()
【发布时间】：2016-07-22 09:22:33
【问题描述】：

我创建了一个 Recyclerview，其中包含 itemobjects、Adapter、viewholder 和 activity。

Recyclerview 工作正常。

我的问题是当从 Recyclerview 中单击一个项目时，我想将用户定向到 TicketDetails 活动。

我有代码来获取被点击的项目及其在视图持有者中的位置，但是当我尝试在视图持有者内部创建一个新活动的新意图时

startActivity(new Intent(getActivity(), TicketDetails.class));

我无法解决 getActivity()

ViewHolder

public class TicketsRecyclerViewHolders extends RecyclerView.ViewHolder implements View.OnClickListener{

    public ImageView priority;
    public TextView sts_open;
    public TextView sts_overdue;
    public TextView tkt_from;
    public TextView tkt_subject;
    public TextView tkt_assignedto;
    public TextView tkt_created_date;
    public TextView txt_ticket_id;

    private SparseBooleanArray selectedItems = new SparseBooleanArray();

    public TicketsRecyclerViewHolders(View itemView) {
        super(itemView);
        itemView.setOnClickListener(this);

        priority = (ImageView) itemView.findViewById(R.id.priority_status_icon);
        sts_open= (TextView) itemView.findViewById(R.id.tv_Tk_opn_status);
        sts_overdue = (TextView) itemView.findViewById(R.id.tv_Tk_overdue);
        tkt_from = (TextView) itemView.findViewById(R.id.tv_Tk_from);
        tkt_subject = (TextView) itemView.findViewById(R.id.tv_Tk_subject);
        tkt_assignedto = (TextView) itemView.findViewById(R.id.tv_Tk_Assignedto);
        tkt_created_date = (TextView) itemView.findViewById(R.id.tv_Tk_Created_date);
        txt_ticket_id = (TextView) itemView.findViewById(R.id.tv_Tk_TicketID);

    }

    @Override
    public void onClick(View view) {
        int position = getAdapterPosition();
        String ticket_id = txt_ticket_id.getText().toString();
        Log.d("ZD-clicked : ", "Position => "+String.valueOf(position)+", Ticket Id => "+ticket_id);

        startActivity(new Intent(getActivity(), TicketDetails.class));

//        if (selectedItems.get(getAdapterPosition(), false)) {
//            selectedItems.delete(getAdapterPosition());
//            view.setSelected(false);
//        }
//        else {
//            selectedItems.put(getAdapterPosition(), true);
//            view.setSelected(true);
//        }
    }
}

适配器

public class TicketsRecyclerViewAdapter extends RecyclerView.Adapter<TicketsRecyclerViewHolders>{

    public List<TicketsItemObject> TicketsItemList;
    private Context context;


    public TicketsRecyclerViewAdapter(Context context, List<TicketsItemObject> itemList) {
        this.TicketsItemList = itemList;
        this.context = context;
    }

    @Override
    public TicketsRecyclerViewHolders onCreateViewHolder(ViewGroup parent, int viewType) {
        View layoutView = LayoutInflater.from(parent.getContext()).inflate(R.layout.custom_tickets_row, null);
        TicketsRecyclerViewHolders rcv = new TicketsRecyclerViewHolders(layoutView);
        return rcv;
    }

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

            holder.priority.setImageResource(TicketsItemList.get(position).getStatus_priority());
            holder.sts_open.setText(TicketsItemList.get(position).getStatus_open());
            holder.sts_overdue.setText(TicketsItemList.get(position).getStatus_overdue());
            holder.tkt_from.setText(TicketsItemList.get(position).getTicket_from());
            holder.tkt_subject.setText(TicketsItemList.get(position).getTicket_subject());
            holder.tkt_assignedto.setText(TicketsItemList.get(position).getTicket_assignedto());
            holder.tkt_created_date.setText(TicketsItemList.get(position).getTicket_created_date());
            holder.txt_ticket_id.setText(TicketsItemList.get(position).getTicket_id());
    }

    @Override
    public int getItemCount() {
        return this.TicketsItemList.size();
    }
}

项目对象

public class TicketsItemObject {
    private int status_priority;
    private String status_open;
    private String status_overdue;
    private String ticket_from;
    private String ticket_subject;
    private String ticket_assignedto;
    private String ticket_created_date;
    private String ticket_id;

    public TicketsItemObject(int status_priority, String status_open, String status_overdue, String ticket_from, String ticket_subject, String ticket_assignedto, String ticket_created_date, String ticket_id) {
        this.status_priority = status_priority;
        this.status_open = status_open;
        this.status_overdue = status_overdue;
        this.ticket_from = ticket_from;
        this.ticket_subject = ticket_subject;
        this.ticket_assignedto = ticket_assignedto;
        this.ticket_created_date = ticket_created_date;
        this.ticket_id =ticket_id;
    }

    public int getStatus_priority() {
        return status_priority;
    }

    public String getStatus_open() {
        return status_open;
    }

    public String getStatus_overdue() {
        return status_overdue;
    }

    public String getTicket_from() {
        return ticket_from;
    }

    public String getTicket_subject() {
        return ticket_subject;
    }

    public String getTicket_assignedto() {
        return ticket_assignedto;
    }

    public String getTicket_created_date(){return ticket_created_date;}

    public String getTicket_id(){return ticket_id;}

}

活动

public class Dashboard extends AppCompatActivity {

    private Toolbar toolbar;
    public DrawerLayout drawerLayout;
    public ListView drawerList;
    private navigationDrawerFragment drawerFragment;

    private CompanyProfileAdapter mAdapter;
    ApplicationEnvironmentURL applicationEnvironment;
    ProgressDialog pDialog;
    Context context;
    String BASEURL;
    String FilteredData;
    String allAgents;
    List<TicketsItemObject> items = new ArrayList<TicketsItemObject>();

    private RecyclerView recyclerView;
    private LinearLayoutManager layoutManager;
    private TicketsRecyclerViewAdapter adapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setTitle("Dashboard");
        setContentView(R.layout.activity_dashboard);

        applicationEnvironment = new ApplicationEnvironmentURL(this.context);
        context = this.getApplicationContext();

        toolbar = (Toolbar) findViewById(R.id.app_bar_dashboard);
        setSupportActionBar(toolbar);
        getSupportActionBar().setDisplayShowHomeEnabled(true);

        drawerFragment = (navigationDrawerFragment)
                getSupportFragmentManager().findFragmentById(R.id.fragment_navigation_drawer);
        drawerFragment.setup(R.id.fragment_navigation_drawer, (DrawerLayout) findViewById(R.id.drawer_layout), toolbar);



        SharedPreferences prefs = getSharedPreferences("zupportdesk", MODE_PRIVATE);
        String islogged = prefs.getString("islogged", "Not defined");
        String userid = prefs.getString("userid", "Not defined");
        String profileToken = prefs.getString("profileToken", "Not defined");
        String companyId = prefs.getString("companyId", "Not defined");
        String companyName = prefs.getString("companyName", "Not defined");
        String ProfileId = prefs.getString("ProfileId", "Not defined");

        Log.d("islogged     : ", islogged);
        Log.d("userid       : ", userid);
        Log.d("profileToken : ", profileToken);
        Log.d("companyId    : ", companyId);
        Log.d("companyName  : ", companyName);
        Log.d("ProfileId    : ", ProfileId);

        recyclerView = (RecyclerView)findViewById(R.id.recycler_view_tickets);
        recyclerView.addItemDecoration(new SimpleDividerItemDecoration(this));
        layoutManager = new LinearLayoutManager(Dashboard.this);
        recyclerView.setLayoutManager(layoutManager);

        getTickets(ProfileId, companyId, profileToken);

        View newTicket = findViewById(R.id.newtic);
        newTicket.setOnClickListener(onClickListener);




    }

    /* Multiple Button on click event handle */
    private View.OnClickListener onClickListener = new View.OnClickListener() {
        @Override
        public void onClick(final View v) {
            switch(v.getId()){
                case R.id.newtic:
                    // Create a login URl, before starting anything

                    if(isNetworkAvailable()){
                        Intent intentTicket = new Intent(Dashboard.this, NewTicket.class);
                        startActivity(intentTicket);
                    } else {showErrorMessage("Please check your internet connection.", "No Connectivity!"); }
                    break;
            }
        }
    };


    private void getTickets(String profileId, String companyId, String profileToken){
        if(isNetworkAvailable()) {
            try {
                setFilteredDataURL(companyId);
                FilteredData = new getFilteredData().execute(profileToken).get();


                Log.d("Full Filtered Data", FilteredData);
                setTicketsURL(profileId, companyId);
            } catch (UnsupportedEncodingException e) {
                e.printStackTrace();
            } catch (InterruptedException e) {
                e.printStackTrace();
            } catch (ExecutionException e) {
                e.printStackTrace();
            }
            new getNewTickets().execute(profileToken);
        }else{ showErrorMessage("Please check your internet connection.", "No Connectivity!"); }
    }
................
.............
..More...........

【问题讨论】：

标签： java android android-recyclerview android-viewholder

【解决方案1】：

getActivity() 仅适用于片段。视图将具有活动上下文。所以从视图中获取上下文。

改变

startActivity(new Intent(getActivity(), TicketDetails.class));

到

Context context = view.getContext();
context.startActivity(new Intent(context, TicketDetails.class));

【讨论】：

Hy Tnx。但现在无法解析startActivity。我清理了项目并反驳了项目Error:(62, 9) error: cannot find symbol method startActivity(Intent)
更新了答案，使用上下文启动Activity。

【解决方案2】：

你可以试试

holder.itemView.context as Activity

【讨论】：

内部onBindViewHolder
您必须在答案中明确提及这些信息。否则答案不完整
在适配器的override fun onBindViewHolder(holder: RecyclerView.ViewHolder, position: Int) 内，您可以通过holder.itemView.context as Activity 获得活动。您可以打开对话框或任何需要在支架内活动的东西。

【解决方案3】：

接口方法

你也可以使用接口解决这个问题

1) 创建界面

public interface ItemclickListerner{

   public void startActivity(int index);

}

2）在Activity中实现接口

public class YourActivity extends AppcompatActivity implements ItemclickListerner{

    protected void onCreate(Bundle bundle)
 
    .......

    @override
    public void startActivity(int index)
    {
       Intent i = new Intent(YourActivity.this, SecondActivity.class)
       startActivity(i);
    }
 
}

3) 在 holder 中使用 ItemclickListerner

public class TicketsRecyclerViewHolders extends ....  {

   private ItemclickListerner listener;

   // Typecast the listener 
   public TicketsRecyclerViewHolders(Context context)
   {
      listener = (ItemclickListerner)context;
   }

   // Call the listener method

   @Override
   public void onBindViewHolder(TicketsRecyclerViewHolders holder, int position{
       listener.startActivity(position)
   }


}

【讨论】：

【解决方案4】：

您可以使用接口将 itemclick 从适配器传递到您的活动或片段。在回调中你可以调用 Intent。

请参阅此thread 了解更多信息。请参阅@Jacob Tabaks 的回答。

编辑：

查看@AkshayBhat 的另一种方法的答案。

【讨论】：

我同意，但是当您可以从视图中获取上下文时，为什么要额外的接口和代码。
同意。以前没用过这种方法。 :)

【解决方案5】：

您的构造函数中有context。因此您可以使用上下文从适配器转到Activity。

Intent goTicket = new Intent(context, MyDetailActivity.class);
 goTicket.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);

【讨论】：

【解决方案6】：

将 fragment 传递给 Adaptar 构造函数。
检查fragment当前是否已添加到其活动中，然后启动特定活动：

if (fragment.isAdded())
```
 fragment.startActivity(intent)
```

【讨论】：