如何获取当前在回收站视图的线性布局中不可见的视图

Question

I was designing an Instagram story type template. I am stuck at a very weird problem. I have used recycler view in the main activity.

MainActivity: (This is just the layout shown. I have change the orientation to Horizontal).

My layout:

Then I have designed a custom adapter and in the layout I have used a linearLayout. When clicked on each view It opens a new Activity which shows the whole story content.

Just like in Instagram when a user opens any story, the user can click on the right side of the screen to get to the next story, or left of the screen to get to the previous one. I tried to implement this same functionality. Opening the story was implemented successfully. The problem comes when I added the functionality of right and left click on the screen. I added two button; one to the right and one to the left. The problem is like, if there are currently 3 views visible, then I can navigate in between these stories only and not to the stories which are not visible in the screen because of the recycler view.

The below code is for right and left clicks

leftArrow = findViewById(R.id.leftArrow);
    leftArrow.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            if(myAdapter.currentPosition - 1 >= 0) {
                int firstVis = MainActivity.linearLayoutManager.findFirstVisibleItemPosition();
                MainActivity.linearLayoutManager.scrollToPosition(firstVis - 1);
                rightOrLeftClicks(myAdapter.currentPosition - 1);
            }
        }
    });

    rightArrow = findViewById(R.id.rightArrow);
    rightArrow.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            if(myAdapter.currentPosition + 1 < myAdapter.localDataSet.length) {
                int lastVis = MainActivity.linearLayoutManager.findLastVisibleItemPosition();
                MainActivity.linearLayoutManager.scrollToPosition(lastVis + 1);
                rightOrLeftClicks(myAdapter.currentPosition + 1);
            }
        }
    });
}

Below code is of the function rightOrLeftClicks

public void rightOrLeftClicks(int position) {
    finish();
    Log.d("rl", "working");
    nextView = MainActivity.linearLayoutManager.getChildAt(position);
    Log.d("ll", "The last element is " + MainActivity.linearLayoutManager.findLastVisibleItemPosition());
    if(nextView != null)myAdapter.onClickView(position, myAdapter.localDataSet[position].symptom, nextView);
}

Below code is for onClickView , It is same code for clicking any view (Story) or clicking the right or left buttons. Basically I just opened the another activity by passing an intent with the next or previous view I obtained when clicked on right or left respectively.

public static void onClickView(int position, String element, View v) {
    Intent intent = new Intent(v.getContext(), MainActivity2.class);
    idPosition = "";
    idPosition = element;
    ArrayList<String> passingContent = new ArrayList<>();
    currentPosition = position;
    passingContent.add(localDataSet[position].description);
    passingContent.add(localDataSet[position].imageUrl);
    intent.putExtra(element + "", passingContent);
    v.getContext().startActivity(intent);
}

The problem is it only gives the visible views to me. Not the rest of the views. I tried auto scrolling so that the next or the previous view become visible but it doesn't seems to work. The last visible position of the child remains the same and it return a null view to me when I try to open the view just after the last visible view.

Assume there are 5 stories. Then I will see only 3 stories in the screen the rest can be seen by scrolling. When I click any of the stories. I can only navigate between 1,2 and 3. When I try to click right from story 3 to see the story 4. The current story is killed by finish() function and null is returned in the nextView variable because of which the story 4 is not loaded and I am returned to the MainActivity.

I have to navigate to all stories present in my recycler view.

Answer 1

Do these changes may help:

1/ I think you should use ViewPager . It automatically snaps to the item without scrollTo to index. Or keep using RecyclerView with the help of SnapHelper

2/ Modify onClickView method not to be static, and don't need View v to work. I see you just need View v just for the context. Why not just pass the context to that method. It's not proper to use a parameter like that, and that approach traps you into 3/ problem.

3/

nextView = MainActivity.linearLayoutManager.getChildAt(position);

You already know how RecyclerView works, just avoid using getChildAt because in some cases, the child you want hasn't been created yet. Base on your code, I think you don't even need to get the nextView

Answer 2

As told by Tam Huynh. The 1st point helped me in getting the new views in the linear layout. The views were working the fine.

There was a problem in the parameter of the function getChildAt . I have to pass the same position I was in previously. Because relatively the position(index) will not change for the child views.

index 0 -> story number 1

index 1 -> story number 2

index 2 -> story number 3

Like if there were story number 1,2 and 3 visible, the index 0 will contain 1st story, index 1 will contain 2nd and index 2 will contain 3rd story. when user clicked the right button on the 3rd story. The 4th story is first visible and now the screen have 2,3 and 4 visible. but the index of the 4th story will remain 3rd only. As now indexing will be like

index 0 -> story number 2

index 1 -> story number 3

index 2 -> story number 4

So, instead of passing position as parameter, currentPosition should be passed in getChildAt