We have a ReciclerView , a list is displayed on the screen. The list is updated every 5 seconds. When you click on a list item, the item expands (to display more information) or narrows back.

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The problem is that the open element is narrowed down because the timer is running.

I need to stop the timer when expanding the element ( handler or runnable or as it is correctly called there), and when it is narrowed, start it again. For this, I wrote 2 methods in MainActivity - startRepeatingTask() and stopRepeatingTask() , but I don’t know how to access them from the ViewHolder class.

MainActivity.java

 public class MainActivity extends AppCompatActivity { RecyclerView recyclerView; RecyclerView.LayoutManager layoutManager; ConnectionItemAdapter adapter; List<ConnectionItem> connectionItems; Handler timerHandler; Runnable timerRunnable; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); InitRecyclerView(); timerHandler = new Handler(); timerRunnable = new Runnable() { @Override public void run() { //тут обновляется адаптер adapter.notifyDataSetChanged(); timerHandler.postDelayed(this, 5000); //каждые 5 секунд } }; timerHandler.postDelayed(timerRunnable, 5000); } void startRepeatingTask() { timerRunnable.run(); } void stopRepeatingTask() { timerHandler.removeCallbacks(timerRunnable); } }

ViewHolder.java

 public class ConnectionItemsAdapterViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener { private boolean isViewExpanded = false; private int originalHeight = 0; public ConnectionItemsAdapterViewHolder(View itemView) { super(itemView); itemView.setOnClickListener(this); fcuName = (TextView)itemView.findViewById(R.id.FcuName); branchName = (TextView) itemView.findViewById(R.id.FcuBranchName); result = (TextView) itemView.findViewById(R.id.ResultText); versionIcon = (ImageView) itemView.findViewById(R.id.versionIcon); // If isViewExpanded == false then set the visibility // of whatever will be in the expanded to GONE if (isViewExpanded == false) { // Set Views to View.GONE and .setEnabled(false) branchName.setVisibility(View.GONE); branchName.setEnabled(false); } } public TextView fcuName; public TextView branchName; public ImageView versionIcon; public TextView result; @Override public void onClick(final View view) { // If the originalHeight is 0 then find the height of the View being used // This would be the height of the cardview if (originalHeight == 0) { originalHeight = view.getHeight(); } // Declare a ValueAnimator object ValueAnimator valueAnimator; if (!isViewExpanded) { branchName.setVisibility(View.VISIBLE); branchName.setEnabled(true); isViewExpanded = true; // Вот где-то тут надо остановить таймер valueAnimator = ValueAnimator.ofInt(originalHeight, originalHeight + (int) (originalHeight * 2.0)); // These values in this method can be changed to expand however much you like } else { isViewExpanded = false; valueAnimator = ValueAnimator.ofInt(originalHeight + (int) (originalHeight * 2.0), originalHeight); Animation a = new AlphaAnimation(1.00f, 0.00f); // Fade out a.setDuration(200); // Set a listener to the animation and configure onAnimationEnd a.setAnimationListener(new Animation.AnimationListener() { @Override public void onAnimationStart(Animation animation) { } @Override public void onAnimationEnd(Animation animation) { branchName.setVisibility(View.INVISIBLE); branchName.setEnabled(false); } @Override public void onAnimationRepeat(Animation animation) { } }); // Set the animation on the custom view branchName.startAnimation(a); } valueAnimator.setDuration(200); valueAnimator.setInterpolator(new AccelerateDecelerateInterpolator()); valueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() { public void onAnimationUpdate(ValueAnimator animation) { Integer value = (Integer) animation.getAnimatedValue(); view.getLayoutParams().height = value.intValue(); view.requestLayout(); } }); valueAnimator.start(); } }

Just started to learn android and java, maybe someone will tell a more correct approach.

  • write a ViewHolder in the same class where RecyclerView initialized (MainActivity same?), and contact as usual: startRepeatingTask() - Jarvis_J

2 answers 2

The correct way is to push the interface through the adapter in the ViewHolder.

  1. We create the interface
 public interface MyInterface { void onClick(); }
  1. Pass it to the adapter's constructor and initialize the link to it in the adapter:
 public class MyAdapter extends .... { private MyInterface mMyInterface; public MyAdapter(MyInterface myInterface) { mMyInterface = myInterface; } }
  1. Pass it also to the ViewHolder when creating it
 public class ConnectionItemsAdapterViewHolder extends RecyclerView.ViewHolder { private MyInterface mMyInterface; public ConnectionItemsAdapterViewHolder(View itemView, MyInterface mMyInterface) { super(itemView); mMyInterface = myInterface; } }
  1. At the right moment, call his method:
 @Override public void onClick(final View view) { mMyInterface.onClick(); }
  1. When creating an adapter in activation, transfer the interface implementation:
 MyAdapter adapter = new MyAdapter(new MyInterface(){ @Override public void onClick(){ startRepeatingTask(); } })

And the easiest way is to cast the context to the activation something like this:

 //в классе ViewHolder ((MainActivity)itemView.getContext()).startRepeatingTask();

    Everything is very boring and dreary:

    1. When creating an adapter RecyclerView in the adapter's constructor we send a link to your Activity
    2. When creating a ViewHolder also ViewHolder link to the Activity from the adapter in the constructor.
    3. Bingo, now we have an Activity in the holder - in the right place we call the Activity methods

    You can certainly implement the ideologically consistent and Orthodox pattern through interfaces, but the game is hardly worth the candle.