使用 RecyclerView 的自定义警报对话框

Question

我正在使用 RecyclerView 列出一些文本，现在我想这样当用户单击文本时会弹出一个自定义警报对话框。

到目前为止我已经试过了但是得到了一个 NullPointerException；这里可能有什么问题？

public class CBAdapter extends RecyclerView.Adapter<CBAdapter.ViewHolder> {

List<AdapterData> mItems;

public CBAdapter() {
    super();
    mItems = new ArrayList<>();
    AdapterData data = new AdapterData();
    data.setTextOne("Many Bows");
    mItems.add(data);

    data = new AdapterData();
    data.setTextOne("Pardon");
    mItems.add(data);

    data = new AdapterData();
    data.setTextOne("Fall To Knees & Beg");
    mItems.add(data);

    data = new AdapterData();
    data.setTextOne("Backflips");
    mItems.add(data);



}

@Override
public ViewHolder onCreateViewHolder(ViewGroup viewGroup, int i) {
    View v = LayoutInflater.from(viewGroup.getContext())
            .inflate(R.layout.test3, viewGroup, false);
    return new ViewHolder(v);
}

@Override
public void onBindViewHolder(ViewHolder viewHolder, int i) {
    AdapterData data = mItems.get(i);
    viewHolder.textOne.setText(data.getTextOne());

}


@Override
public int getItemCount() {

    return mItems.size();
}

class ViewHolder extends RecyclerView.ViewHolder{

    public TextView textOne;
    private Context context;





    public ViewHolder(View itemView) {
        super(itemView);
        textOne = (TextView)itemView.findViewById(R.id.textView1);

        itemView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                final Dialog dialog = new Dialog(context);
                dialog.setContentView(R.layout.custom_dialog);
                dialog.setTitle("Title");

                TextView text = (TextView) dialog.findViewById(R.id.text);
                text.setText("hello world");

                ImageView image = (ImageView) dialog.findViewById(R.id.image);
                image.setImageResource(R.drawable.ic_launcher);

                Button dialogButton = (Button) dialog.findViewById(R.id.dialogButtonOK);

                dialogButton.setOnClickListener(new View.OnClickListener() {
                    @Override
                    public void onClick(View v) {
                        dialog.dismiss();
                    }
                });

                dialog.show();
            }
        });


    }
}
}

Answer 1

这不是您查询的答案，而是处理这种情况的更好方法。

Use callback methods.

在你的Activity中：

这将实现我们 Adapter 中的接口。在此示例中，当用户单击 RecyclerView.

中的项目时将调用它

  public class MyActivity extends Activity implements AdapterCallback {

    private MyAdapter mMyAdapter;

    @Override
    public void onMethodCallback() {
       // Show your alert
    }

    @Override
    protected void onCreate(final Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        this.mMyAdapter = new MyAdapter(this);
    }
}

在您的适配器中：

在 Activity 中，我们启动了 Adapter 并将其作为参数传递给构造函数。这将为我们的回调方法启动我们的接口。可以看到我们使用了我们的用户点击回调方法。

public class MyAdapter extends RecyclerView.Adapter<MyAdapter.ViewHolder> {

    private AdapterCallback mAdapterCallback;

    public MyAdapter(Context context) {
        try {
            this.mAdapterCallback = ((AdapterCallback) context);
        } catch (ClassCastException e) {
            throw new ClassCastException("Activity must implement AdapterCallback.");
        }
    }

    @Override
    public void onBindViewHolder(final MyAdapter.ViewHolder viewHolder, final int i) {
        // simple example, call interface here
        // not complete
        viewHolder.itemView.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                try {
                    mAdapterCallback.onMethodCallback();
                } catch (ClassCastException exception) {
                   // do something
                }
            }
        });
    }

    public static interface AdapterCallback {
        void onMethodCallback();
    }
}

礼貌： Call Activity method from adapter

Answer 2

final Dialog dialog = new Dialog(your_activity_context);

Answer 3

您正在使用 context，它是 null，因此在 ViewHolder 构造函数和 CBAdapter[ 中传递 context =22=] 构造函数也如下所示：

public class CBAdapter extends RecyclerView.Adapter<CBAdapter.ViewHolder> { List<AdapterData> mItems; Context context; public CBAdapter(Context context) { super(); this.context = context; ..... }

并且在ViewHolder中class

class ViewHolder extends RecyclerView.ViewHolder{ public TextView textOne; private Context mcontext; public ViewHolder(View itemView, Context mcontext) { super(itemView); this.mcontext = mcontext; .... }

Answer 4

编写此代码：

 final Dialog dialog = new Dialog(CBAdapter.this);

而不是

final Dialog dialog = new Dialog(context);

(或)

context = CBAdapter.this; // Initialize context

希望对您有所帮助。

快乐编码:)

Answer 5

没关系我忘了初始化我的上下文

上下文=itemView.getContext();

Answer 6

与问题没有直接关系，尽管我请求你：不要在适配器中设置 onClickListener-s！

应该这样做：

private class ItemDataHolder extends RecyclerView.ViewHolder implements View.OnLongClickListener{

    private final String TAG = ItemDataHolder.class.getSimpleName();

    /**
     * Define view's elements
     */

    /**
     *  Define object instance
     */
    private Item mData;

    // Constructor
    public MessageDataHolder(View itemView) {
        super(itemView);
        /**
         * Init elements
         */
        itemView.setOnLongClickListener(this);
    }

    /**
     * Method to handle long click on the item
     * @param v View to handle click on
     * @return
     */
    @Override
    public boolean onLongClick(View v) {
        Log.v(TAG, "Long click fired!");
        return false;
    }

    /**
     * Function to update view's elements
     * @param message Good data to be updated to
     */
    public void bindData(Item message) {
        mData = message;
        /**
        * Set values of views here
        **/
    }
}

希望我的回答能帮助别人写出更好的代码:)

使用 RecyclerView 的自定义警报对话框

Custom Alert Dialog With RecyclerView

android

android-alertdialog

android-recyclerview