单击 RecyclerView 后，当我想在新活动中显示详细信息时出现错误。 使用 Firebase

Question

I would like the ViewProduct activity to show the detail of the item clicked on the recyclerView . My aim later is to change the textView to a editText to edit the products, but for now I would like it to show.

My problem is filling the textView with the data from the particular product from Firebase.

You will see there is a toast message that is commented out which works and show the position, so I know I am on the right track somehow. Now the app just crashes if I click on the item, giving error:

Unable to start activity ComponentInfo

Attempt to invoke virtual method 'java.lang.String java.lang.Object.toString()' on a null object reference

All I need now is to populate the textfield s with the data from Firebase.

Here is my itemView in my RecyclerAdapter:

            itemView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                int position = getAdapterPosition();
                //Toast.makeText(context,"Position"+ position, Toast.LENGTH_SHORT).show();
                if (position != RecyclerView.NO_POSITION && listener != null) {
                    //listener.onItemClick(getSnapshots().getSnapshot(position), position);
                    listener.onItemClick(getSnapshots().getSnapshot(position),(position));
                    Intent intent = new Intent(itemView.getContext(), ViewProduct.class);
                    intent.putExtra("product_ID:", position);
                    itemView.getContext().startActivity(intent);

                }
            }
        });

And here is my ViewProduct Activity where I want to see the details: public class ViewProduct extends AppCompatActivity {

private String edit_product_ID;

private TextView mProduct, mPrice;
private TextView mSave, mDelete;

private DatabaseReference product_ref;



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

product_ref = FirebaseDatabase.getInstance().getReference().child("ultra_liquors");

edit_product_ID = getIntent().getExtras().get("product_ID").toString();


    //Toast.makeText(this, "The Product ID:" + edit_product_ID, Toast.LENGTH_SHORT).show();

    mProduct = (TextView) findViewById(R.id.product);
    mPrice = (TextView) findViewById(R.id.price);
    mSave = (TextView) findViewById(R.id.save);
    mDelete = (TextView) findViewById(R.id.delete);

    RetrieveProductInfo();

}

private void RetrieveProductInfo() {
    product_ref.child(edit_product_ID).addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
            if ((dataSnapshot.exists()) && (dataSnapshot.hasChild(edit_product_ID))) {
                String product_name = dataSnapshot.child("product").getValue().toString();
                String product_price = dataSnapshot.child("price").getValue().toString();

                mProduct.setText(product_name);
                mPrice.setText(product_price);
            }
        }

        @Override
        public void onCancelled(@NonNull DatabaseError error) {

        }
    });
}

Answer 1

The string in intent.putExtra("product_ID:", position); has a trailing colon-symbol behind it. which causes getExtras().get(...) to return null. null.toString() throws the error

Answer 2

Add this line with Intent

intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);

I think that was the issue try it and let me know!