Question

MainActivity [A]

    public class ViewActivity extends AppCompatActivity implements
        FilterDialogFragment.FilterListener,
        AffichageAdapter.OnAffichageSelectedListener {

   public void onCreate(Bundle savedInstanceState) {
           super.onCreate(savedInstanceState);
           setContentView(R.layout.activity_view);
           ButterKnife.bind(this);

[B]类：当我单击它在ViewActivity中显示时，我想创建一个AlertDialogue

public class AffichageAdapter extends FirestoreAdapter<AffichageAdapter.ViewHolder> {

AlertDialog.Builder Alert = new AlertDialog.Builder(What i Put here ! );

Answer 1

YourClassName.this或getContext()

Answer 2

如果您试图在MainActivity A中显示来自其他类的警报。您应该将MainActivity的getContext（）参数传递给该B类的show alert函数。

Answer 3

在SELECT *, COUNT(mobile_no) FROM duplicate GROUP BY mobile_no HAVING COUNT(mobile_no) > 1;类中，您可以这样声明一个字段：

AffichageAdapter

和private Context mContext; public AffichageAdapter(Context context){ this.mContext = context;//get context by constructor }

中

ViewActivity

然后：

AffichageAdapter adapter = new AffichageAdapter(this);//"this" means ViewActivity, its a context.
xxx.setAdapter(adapter); // in some place.

为另一个类[CONTEXT]中的活动创建AletDialog

3 个答案: