从回收站视图按钮单击更改不同的按钮文本

Question

In my main activity page, i have a recycler view that has buttons for each item. As i click an item button, i want it to update the text on the Shopping cart button to show the count of items in the cart.The shopping cart button is outside of the recycler view.

I already setup a global variable that records the count of items in the cart, but i can't figure out how to display that count on the button. Mostly, i can't figure out how that button text can update when i click another item in the recycler view.

Thanks in advance!

In my Main Activity (where the recycler view is located and the button i want the text to change on is located), I've created a method init2.

public void init2() {
    shopbutton = (Button) findViewById(R.id.button2);
   String countshopS = "hello";
   shopbutton.setText(countshopS);
}

then i try to call the method init2 from the Onclick Listener of the Adapter where the button rows are.

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

private MainActivity main = new MainActivity();


holder.priceset.setOnClickListener(new View.OnClickListener() {
        @SuppressLint("SetTextI18n")
        @Override
        public void onClick(View v) {

            main.init2();

I get the response "Attempt to invoke virtual method 'android.content.pm.ApplicationInfo android.content.Context.getApplicationInfo()' on a null object reference" on the row where the Id of the button is identified in init2();

Answer 1

Use callback in your Adapter and increase for every click on row's button .

Then implement callback in your activity and do all things you need for example show finial price or count or...

Do not use statics and handle every rows count with data model (transiant maybe useful) and callbacks and interfaces.