How to handle "ReadMore" Button click present in my List

Question

BusinessForSaleActivity

public class BusinessForSaleActivity extends AppCompatActivity {

    DatabaseReference databaseLinks;
    ListView listViewBusinessForSale;
    Button readMore;
    ArrayList<BusinessForSale> list;
    //CardView cardView;

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

        listViewBusinessForSale = (ListView)findViewById(R.id.ListViewBusinessForSale);

        list = new ArrayList<>();

        databaseLinks = FirebaseDatabase.getInstance().getReference("BusinessList");

        databaseLinks.addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(@NonNull DataSnapshot dataSnapshot) {

                list.clear();
                try{
                    for(DataSnapshot businessSnapshot : dataSnapshot.getChildren()){
                        BusinessForSale b = businessSnapshot.getValue(BusinessForSale.class);

                        list.add(b);
                    }
                }
                catch (Exception ex){
                    Log.e("Error Descr:",ex.getMessage());
                }


                BusinessForSaleList adapter=new BusinessForSaleList(BusinessForSaleActivity.this,list);
                listViewBusinessForSale.setAdapter(adapter);
            }

            @Override
            public void onCancelled(@NonNull DatabaseError databaseError) {
                Toast.makeText(BusinessForSaleActivity.this,"Something is wrong",Toast.LENGTH_SHORT).show();
            }
        });


    }
}

BusinessForSaleList================(Adapter class)============

public class BusinessForSaleList extends ArrayAdapter<BusinessForSale> {

        private Activity context;
        private List<BusinessForSale> businessForSaleList;

        public BusinessForSaleList(Activity context,List<BusinessForSale> businessForSaleList){
            //super(context,R.layout.list_layout,businessForSaleList);
            super(context,R.layout.list,businessForSaleList);
            this.context=context;
            this.businessForSaleList=businessForSaleList;
        }

        @NonNull
        @Override
        public View getView(final int position, @Nullable View convertView, @NonNull ViewGroup parent) {
            LayoutInflater inflater=context.getLayoutInflater();

            View listViewItem=inflater.inflate(R.layout.list,null,true);

            ImageView imgBuiness=(ImageView)listViewItem.findViewById(R.id.imgViewBusiness);
            TextView txtTitle = (TextView)listViewItem.findViewById(R.id.txtViewTitle);
            TextView txtType = (TextView)listViewItem.findViewById(R.id.txtViewType);
            TextView txtDescr = (TextView)listViewItem.findViewById(R.id.txtViewDescr);
            Button btnReadMore = (Button)convertView.findViewById(R.id.buttonReadMore);

            BusinessForSale businessForSale = businessForSaleList.get(position);
            Picasso.get().load(businessForSale.getImage().toString()).into(imgBuiness);
            txtTitle.setText(businessForSale.getBusiness_Title());
            txtType.setText(businessForSale.getBusiness_Type());
            txtDescr.setText(businessForSale.getDescription());


            return listViewItem;
        }
    }

BusinessForSaleActivity.xml==============================================

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".BusinessForSaleActivity">

    <ListView
        android:id="@+id/ListViewBusinessForSale"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:footerDividersEnabled="false"
        />

</RelativeLayout>

List.xml================================================================

[<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#e0e0e0">

    <android.support.v7.widget.CardView
        android:id="@+id/cardBusinessForSale"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_margin="16dp"
        app:cardCornerRadius="8dp"
        app:cardElevation="4dp">
        <LinearLayout
            android:id="@+id/L1"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:orientation="vertical">

            <ImageView
                android:id="@+id/imgViewBusiness"
                android:layout_width="match_parent"
                android:layout_height="160dp"
                android:layout_margin="4dp"
                android:scaleType="centerCrop"/>

            <LinearLayout
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:orientation="vertical"
                android:padding="16dp">
                <TextView
                    android:id="@+id/txtViewTitle"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:text="TextView"
                    android:layout_marginBottom="8dp"
                    android:textColor="#000"
                    android:textSize="18sp"/>
                <TextView
                    android:id="@+id/txtViewType"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:text="TextView"
                    android:textColor="#555" />
            </LinearLayout>
            <LinearLayout
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:padding="16dp"
                android:orientation="vertical">
                <TextView
                    android:id="@+id/txtViewDescr"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:text="TextView"
                    android:maxLines="3"
                    android:textSize="14sp" />
            </LinearLayout>
            <LinearLayout
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:padding="16dp">
                <Button
                    android:id="@+id/buttonReadMore"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:theme="@style/PrimaryFlatButton"
                    android:text="Read More" />

                <Button
                    android:id="@+id/buttonAddToFvrt"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:theme="@style/PrimaryFlatButton"
                    android:text="Add to Favorites" />
            </LinearLayout>
        </LinearLayout>
    </android.support.v7.widget.CardView>



</RelativeLayout>][1]

I want to redirect to new Activity on "ReadMore" button click. I am fetching firebase data into a listview using list.xml layout.

Answer 1

When you're using a list and need to handle click on an item or an element contained by it, the common way is to set a listener in the getView() method or onBind() method, depending on the adepter you're using.

In this case, in your "getView()" method, after referenced your button you need to set a listener on it that retrieve the position of the item that contains it and open the relative activity (or the unique activity setting up the correct value). You can do it by retrieving the parent position of its parent, but it's sounds so complicated.

The best and common way is to assign to the button a tag that is the position assigned to its parent by the getView() method in this way:

 @NonNull
 @Override
 public View getView(final int position, @Nullable View convertView, @NonNull ViewGroup parent) {
    LayoutInflater inflater=context.getLayoutInflater();
    View listViewItem=inflater.inflate(R.layout.list,null,true);
    ...
    Button btnReadMore = (Button)convertView.findViewById(R.id.buttonReadMore);
    btnReadMore.setTag(position + "");
}

After that, every button contains the position of the item in the list. Now, assign the listener to the button and retrieve the correct position:

btnReadMore.setOnClickListener(new OnClickListener(){
@Override
public void onClick(View view,....){
    Button btnReadMore = (Button) view; //This cast is unless, it's here only for more understanding
    String positionString = btnReadMore.getTag();
    int position = Integer.parseInt(positionString);
    BusinessForSale correctItem = BusinessForSaleList.get(position);
    //here start activity you need.
}});

Hope this help! :D