android - 在Firebase中单击 ListView 中的项目，从Fire base中删除数据

我正在开发一个android应用程序，它必须通过单击列表项从Firebase中删除数据。
在列表中从Firebase中检索的数据，但是当我单击列表项删除数据时，它显示了白屏幕，然后退出到活动中。
我已经创建了一个当我单击一个项目时应该打开的Dialog Box。
这是我的Dialog Box

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingTop="200dp"
    android:background="#3E80B4"
    android:orientation="vertical">
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="vertical">
        <TextView
            android:id="@+id/txt_dia"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="center"
            android:layout_margin="10dp"
            android:text="Do you realy want to delete Medicine ?"
            android:textColor="@android:color/white"
            android:textSize="15dp"
            android:textStyle="bold"/>

        <LinearLayout
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="center"
            android:background="#3E80B4"
            android:orientation="horizontal" >

            <Button
                android:id="@+id/btn_yes"
                android:layout_width="100dp"
                android:layout_height="30dp"
                android:background="@android:color/white"
                android:clickable="true"
                android:text="Yes"
                android:textColor="#5DBCD2"
                android:textStyle="bold" />

            <Button
                android:id="@+id/btn_no"
                android:layout_width="100dp"
                android:layout_height="30dp"
                android:layout_marginLeft="5dp"
                android:background="@android:color/white"
                android:clickable="true"
                android:text="No"
                android:textColor="#5DBCD2"
                android:textStyle="bold" />
        </LinearLayout>
    </LinearLayout>
</LinearLayout>

这是我的删除项目活动，当我单击项目时，它会打开Dialog Box

public class ExpiryItemActivity extends AppCompatActivity {
    ListView mylistView;
    DatabaseReference db;
    public Dialog MyDialog;
    TextView tvDeleteDiaog;
    public Button Yes, No;
    Integer value;
    List<ClassMedicine> medicineList;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_expiry_item);
        mylistView= findViewById(R.id.mylistexpiry);
        Yes = findViewById(R.id.btn_yes);
        No = findViewById(R.id.btn_no);
        tvDeleteDiaog= findViewById(R.id.txt_dia);
        medicineList= new ArrayList<>();
        db= FirebaseDatabase.getInstance().getReference("medicines");
    }
    @Override
    protected void onStart() {
        super.onStart();
        db.addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(DataSnapshot dataSnapshot) {
                medicineList.clear();
                for (DataSnapshot medicineSnapshot:dataSnapshot.getChildren()){
                    ClassMedicine classMedicine=medicineSnapshot.getValue(ClassMedicine.class);
                    medicineList.add(classMedicine);
                }
                MedicineList adapter=new MedicineList(ExpiryItemActivity.this,medicineList);
                mylistView.setAdapter(adapter);
            }
            @Override
            public void onCancelled(DatabaseError databaseError) {
            }
        });

        mylistView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                value=mylistView.getId();
                Toast.makeText(ExpiryItemActivity.this, "Here" + value.toString(), Toast.LENGTH_SHORT).show();
                customDialog();
            }

            private void customDialog() {
                MyDialog = new Dialog(ExpiryItemActivity.this);
                MyDialog.setContentView(R.layout.xmldialog);
                MyDialog.setTitle("Delete Medicine?");
                Toast.makeText(ExpiryItemActivity.this, value.toString(), Toast.LENGTH_SHORT).show();
                final DatabaseReference child1 = db.child("medicine");
                Toast.makeText(ExpiryItemActivity.this, "Here me", Toast.LENGTH_SHORT).show();
                Yes.setOnClickListener(new View.OnClickListener() {
                    @Override
                    public void onClick(View v) {
                        child1.child("mediDate").child(String.valueOf(value)).removeValue();
                        MyDialog.cancel();
                    }
                });
                No.setOnClickListener(new View.OnClickListener() {
                    @Override
                    public void onClick(View v) {
                        MyDialog.cancel();
                    }
                });
                MyDialog.show();
            }

        });
    }
}

这个类用于如何从Firebase中获取列表中的数据。

最佳答案

为了从列表中删除Dialog Box中的数据，布局文件将保持与您设计的相同。
以及从列表中以及从Firebase中删除列表项的Java文件。

public class ExpiryItemActivity extends AppCompatActivity {
    ListView mylistView;
    DatabaseReference db;
    public Dialog MyDialog;
    TextView tvDeleteDiaog;
    public Button Yes, No;
    String value;
    List<ClassMedicine> medicineList;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_expiry_item);
        mylistView= findViewById(R.id.mylistexpiry);

        tvDeleteDiaog= findViewById(R.id.txt_dia);
        medicineList= new ArrayList<>();
        db= FirebaseDatabase.getInstance().getReference("medicines");
    }
    @Override
    protected void onStart() {
        super.onStart();
        db.addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(DataSnapshot dataSnapshot) {
                medicineList.clear();
                for (DataSnapshot medicineSnapshot:dataSnapshot.getChildren()){
                    ClassMedicine classMedicine=medicineSnapshot.getValue(ClassMedicine.class);
                    medicineList.add(classMedicine);
                }
                MedicineList adapter=new MedicineList(ExpiryItemActivity.this,medicineList);
                mylistView.setAdapter(adapter);
            }
            @Override
            public void onCancelled(DatabaseError databaseError) {
            }
        });

        mylistView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                //value=ClassMedicine.getMedicineId();
                ClassMedicine c=medicineList.get(position);
                value=c.getMedicineId().toString();
                customDialog();
            }
            private void customDialog() {
                MyDialog = new Dialog(ExpiryItemActivity.this);
                MyDialog.setContentView(R.layout.xmldialog);
                MyDialog.setTitle("Delete Medicine?");
                final DatabaseReference child1 = db.child("medicine");
                Yes = MyDialog.findViewById(R.id.btn_yes);
                No = MyDialog.findViewById(R.id.btn_no);
                Yes.setOnClickListener(new View.OnClickListener() {
                    @Override
                    public void onClick(View v) {
                      String x=  value.toString();
                        db.child(String.valueOf(value)).removeValue();
                        MyDialog.cancel();
                    }
                });
                No.setOnClickListener(new View.OnClickListener() {
                    @Override
                    public void onClick(View v) {
                        MyDialog.cancel();
                    }
                });
                MyDialog.show();
            }
        });
    }
}