如何处理卡片视图中不同的按钮onclick和传递意图？

问题描述 投票：0回答：2

我有一个卡片视图，用于显示即将举行的活动，包括标题，日期等。有两个图像视图应用作按钮：如果单击一个，则应进入参与确认活动，如果单击另一个，则在详细信息上活动。两者都应使用意图（名称，日期，用户ID，令牌）传递信息。我遵循了this tutorial，因为这是最接近我的问题的解决方案，但仍然无法解决。无论我如何更改，这些都是我得到的错误：尝试在空对象引用上调用虚拟方法“ void android.widget.ImageView.setOnClickListener（android.view.View $ OnClickListener）”（这是在我调用setButtons函数时给出的） ，或者如果onclick以某种方式起作用，则意图不会通过，并且我会得到nullpointerexception。我确保使用了正确的ID和名称。附加信息：我正在使用Laravel，并进行了改装。EventsActivity：

public class EventsActivity extends AppCompatActivity {
private static final String TAG = "EventsActivity";
private static final int ACTIVITY_NUM = 1;
private static final String PREFS_NAME = "LoginPrefs";
public static final String EVENT_DETAIL = "EVENT_DETAIL";
private Context mContext = EventsActivity.this;
private Event mEvent = new Event();
private String token, name;
private int id;
private EventAdapter adapter;
private RecyclerView recyclerView;
private List<Event> eventList = new ArrayList<>();
private List<Response> result;
private TextView noEvents;
private Button add, more;

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

    //Get token and id from shared preferences
    SharedPreferences settings = getSharedPreferences(PREFS_NAME, 0);
    token = settings.getString("token", "");
    id = settings.getInt("id", 0);
    Log.d(TAG, "onResponse: id " + id + "token " + token);

    noEvents = findViewById(R.id.noEvents);
    recyclerView = findViewById(R.id.event_recyclerview);
    RecyclerView.LayoutManager layoutManager = new LinearLayoutManager(mContext);
    recyclerView.setLayoutManager(layoutManager);
    adapter = new EventAdapter(mContext, eventList);
    recyclerView.setAdapter(adapter);

    adapter.setOnItemClickListener(new EventAdapter.OnItemClickListener() {
        @Override
        public void onAddClicked(int position) {
           addClick(position);
        }

        @Override
        public void onMoreClicked(int position) {
            moreClick(position);
        }
    });

    loadData();
    setButtons();
}

public void addClick(int position){
    final Event event = eventList.get(position);
    Intent i = new Intent(EventsActivity.this, EventInvitationActivity.class);
    i.putExtra("name", event.getName());
    i.putExtra("name", event.getDescription());
    i.putExtra("name", event.getDate());
    i.putExtra("name", event.getLocation());
    Log.i("hello", event.getName());
    startActivity(i);
}

public void moreClick(int position){
    final Event event = eventList.get(position);
    Intent i = new Intent(EventsActivity.this, EventDetailActivity.class);
    i.putExtra("name", event.getName());
    Log.i("hello", event.getName());
    startActivity(i);
}

void setButtons() {
     add = findViewById(R.id.add_icon);
     more = findViewById(R.id.more_icon);
    Log.d(TAG, "setButtons: called");
    add.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Log.d(TAG, "onClick: add onclicklistener");
            int position = Integer.parseInt(v.getTag().toString());
            addClick(position);
        }
    });
    more.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            int position = Integer.parseInt(v.getTag().toString());
            moreClick(position);
        }
    });
}

//Listing events
private void loadData(){
    ApiEvents service = RetrofitBuilder.getRetrofitInstance().create(ApiEvents.class);
    Call<List<Event>> call = service.listEvents("Bearer" + token, id);
    call.enqueue(new Callback<List<Event>>() {
        @Override
        public void onResponse(@NonNull Call<List<Event>> call, @NonNull Response<List<Event>> response) {
            if (response.isSuccessful() && response.body()!=null) {
                Log.d(TAG, "onResponse: loadData called");
                eventList = response.body();
                adapter = new EventAdapter(mContext, eventList);
                recyclerView.setAdapter(adapter);
                adapter.setOnItemClickListener(new EventAdapter.OnItemClickListener() {
                    @Override
                    public void onAddClicked(int position) {
                        addClick(position);
                    }

                    @Override
                    public void onMoreClicked(int position) {
                        moreClick(position);
                    }
                });
            }
            else if(response.body() == null){
                noEvents.setVisibility(View.VISIBLE);
            }
            else{
                Log.d(TAG, "onResponse: " + response.body());
            }
        }

        @Override
        public void onFailure(@NonNull Call<List<Event>> call, @NonNull Throwable t) {
            Log.d("Response", "onFailure: " + t.toString());
        }
    });
}

}

EventAdapter

public class EventAdapter extends RecyclerView.Adapter<EventAdapter.MyViewHolder> {
private Context mContext;
private List<Event> eventList;
private static final String TAG = "EventDetailActivity";
private OnItemClickListener clickListener;

public EventAdapter(Context mContext, List<Event> eventList){
    this.mContext = mContext;
    this.eventList = eventList;
}

public interface OnItemClickListener {
    void onAddClicked(int position);
    void onMoreClicked(int position);
}

public void setOnItemClickListener(OnItemClickListener clickListener) {
    this.clickListener = clickListener;
}

@NonNull
@Override
public MyViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
    View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.event_layout, parent, 
false);
    return new MyViewHolder(view);
}

@Override
public void onBindViewHolder(@NonNull final MyViewHolder holder, int position) {
    Event event = eventList.get(position);
    holder.itemView.setTag(event);
    holder.title.setText(eventList.get(position).getName());
    holder.description.setText(eventList.get(position).getDescription());
    holder.date.setText(eventList.get(position).getDate());
    holder.location.setText(eventList.get(position).getLocation());
    holder.add.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            if(clickListener != null){
                int position = (int)v.getTag();
                clickListener.onAddClicked(position);
                final Event event = (Event)v.getTag();
                if(event!= null){
                    Intent i = new Intent(mContext, EventInvitationActivity.class);
                    i.putExtra("EVENT_DETAIL", event);
                    v.getContext().startActivity(i);
                }
            }
        }
    });

    holder.more.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            if(clickListener != null){
                int position = (int)v.getTag();
                clickListener.onMoreClicked(position);
                final Event event = (Event)v.getTag();
                if(event!= null){
                    Intent i = new Intent(mContext, EventDetailActivity.class);
                    i.putExtra("EVENT_DETAIL", event);
                    v.getContext().startActivity(i);
                }
            }
        }
    });


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

public class MyViewHolder extends RecyclerView.ViewHolder {
    TextView title, description, date, location;
    Button add, more;

    public MyViewHolder(@NonNull View itemView) {
        super(itemView);
        title = itemView.findViewById(R.id.event_name);
        description = itemView.findViewById(R.id.event_description);
        date = itemView.findViewById(R.id.event_date);
        location = itemView.findViewById(R.id.event_location);
        add = itemView.findViewById(R.id.add_icon);

    }

}

这是我试图在两个活动中获得通过的意图的方式：

//Getting resources
    mName = findViewById(R.id.eventName);
    mDescription = findViewById(R.id.description);
    mLocation = findViewById(R.id.location);
    mDate = findViewById(R.id.date);

    mEvent = Objects.requireNonNull(getIntent().getExtras()).getParcelable(EVENT_DETAIL);
   if(mEvent != null){
    mName.setText(mEvent.getName());
    mDescription.setText(mEvent.getDescription());
    mLocation.setText(mEvent.getLocation());
    mDate.setText(mEvent.getDate());
   }

这是卡片视图中的一个按钮示例：

<Button
            android:id="@+id/add_icon"
            android:layout_width="80dp"
            android:layout_height="40dp"
            android:layout_below="@+id/image"
            android:layout_gravity="center_horizontal"
            android:layout_marginTop="5dp"
            android:layout_toEndOf="@id/event_description"
            android:drawableStart="@drawable/ic_add_black_24dp"
            android:scaleType="centerCrop"
            android:transitionName="img"
            android:visibility="visible"
            android:textColor="@color/colorAccent"
           />

所以问题是，我该如何进行这项工作？

java android android-recyclerview recycler-adapter android-cardview
2个回答
0
投票
在您的MyViewHolder构造函数中，您没有初始化more，因此它将为null，因此将引发null引用异常
0
投票
我假设发生崩溃的单击是more按钮单击侦听器，如果是，则它是因为您没有初始化按钮more：

public MyViewHolder(@NonNull View itemView) { super(itemView); title = itemView.findViewById(R.id.event_name); description = itemView.findViewById(R.id.event_description); date = itemView.findViewById(R.id.event_date); location = itemView.findViewById(R.id.event_location); add = itemView.findViewById(R.id.add_icon); //here you must initialize more also more = itemView.findViewById(.......); } 

现在传递数据并将其用于其他活动，我建议您传递单个数据：
holder.add.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {
        if(clickListener != null){
            int position = (int)v.getTag();
            clickListener.onAddClicked(position);
            final Event event = (Event)v.getTag();
            if(event!= null){
                Intent i = new Intent(mContext, EventInvitationActivity.class);
                i.putExtra("name", event.getName());
                i.putExtra("date", event.getDate());
                i.putExtra("description", event.getDescription());
                i.putExtra("location", event.getLocation());
                v.getContext().startActivity(i);
            }
        }
    }
});


//do the same for more button

在EventInvitationActivity中：
...........

//get the data
String name = getIntent().getStringExtra("name");
String date = getIntent().getStringExtra("date");
String description = getIntent().getStringExtra("description");
String location = getIntent().getStringExtra("location");

//set the data
mName.setText(name);
mDescription.setText(description);
mLocation.setText(location);
mDate.setText(date);
.........
最新问题
© www.soinside.com 2019 - 2024. All rights reserved.