如何将TabLayout与Recyclerview同步? [英] How to sync TabLayout with Recyclerview?

问题描述

我有一个TabLayout和Recyclerview，因此当单击选项卡时，Recyclerview会滚动到特定位置. 我也希望执行相反的过程，以便当Recyclerview滚动到特定位置时，该特定选项卡会突出显示.

I have a TabLayout with Recyclerview so that when tabs are clicked then the Recyclerview is scrolled to a particular position. I want the reverse procedure as well such that when the Recyclerview is scrolled to a particular position then the particular tab is highlighted.

例如:如果TabLayout中有4个选项卡，并且当Recyclerview滚动到第5个位置(项目可见且在TabLayout以下)时，则应突出显示第3个选项卡./i.stack.imgur.com/TYH89.png"rel =" noreferrer>

For example: If there are 4 tabs in the TabLayout and when Recyclerview is scrolled to 5th position(Item visible and below TabLayout) then 3rd tab should be highlighted.

此处，当TabLayout下面显示工作原理"时，应突出显示工作原理"标签.

Here when 'How it works' appears below TabLayout then tabs 'How it works' should be highlighted.

推荐答案

尝试一下

按照此步骤

1. 在您的RecyclerView
中添加ScrollListener
2. 比找不到您的RecyclerView
的第一个可见物品
3. 根据RecyclerView的位置设置TabLayout中的选择标签

1. Add a ScrollListener to your RecyclerView
2. than find first visible item of your RecyclerView
3. set the select the tab in TabLayout as per position of your RecyclerView

示例代码

    myRecyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
        @Override
        public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
            super.onScrolled(recyclerView, dx, dy);

            int itemPosition=linearLayoutManager.findFirstCompletelyVisibleItemPosition();

            if(itemPosition==0){ //  item position of uses
                TabLayout.Tab tab = myTabLayout.getTabAt(Index);
                tab.select();
            }else if(itemPosition==1){//  item position of side effects 
                TabLayout.Tab tab = myTabLayout.getTabAt(Index);
                tab.select();
            }else if(itemPosition==2){//  item position of how it works
                TabLayout.Tab tab = myTabLayout.getTabAt(Index);
                tab.select();
            }else if(itemPosition==3){//  item position of precaution 
                TabLayout.Tab tab = myTabLayout.getTabAt(Index);
                tab.select();
            }
        }
    });

编辑

public class MyActivity extends AppCompatActivity {


    RecyclerView myRecyclerView;
    TabLayout myTabLayout;
    LinearLayoutManager linearLayoutManager;
    ArrayList<String> arrayList = new ArrayList<>();
    DataAdapter adapter;
    private boolean isUserScrolling = false;
    private boolean isListGoingUp = true;




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

        myTabLayout = findViewById(R.id.myTabLayout);



        myRecyclerView = findViewById(R.id.myRecyclerView);
        linearLayoutManager = new LinearLayoutManager(this);
        myRecyclerView.setLayoutManager(linearLayoutManager);
        myRecyclerView.setHasFixedSize(true);

        for (int i = 0; i < 120; i++) {
            arrayList.add("Item " + i);
        }

        adapter= new DataAdapter(this,arrayList);
        myRecyclerView.setAdapter(adapter);

        myTabLayout.addOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
            @Override
            public void onTabSelected(TabLayout.Tab tab) {
                isUserScrolling = false ;
                int position = tab.getPosition();
                if(position==0){
                    myRecyclerView.smoothScrollToPosition(0);
                }else if(position==1){
                    myRecyclerView.smoothScrollToPosition(30);
                }else if(position==2){
                    myRecyclerView.smoothScrollToPosition(60);
                }else if(position==3){
                    myRecyclerView.smoothScrollToPosition(90);
                }
            }

            @Override
            public void onTabUnselected(TabLayout.Tab tab) {

            }

            @Override
            public void onTabReselected(TabLayout.Tab tab) {

            }
        });
        myRecyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {

            @Override
            public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
                if (newState == RecyclerView.SCROLL_STATE_DRAGGING) {
                    isUserScrolling = true;
                    if (isListGoingUp) {
                        //my recycler view is actually inverted so I have to write this condition instead
                        if (linearLayoutManager.findLastCompletelyVisibleItemPosition() + 1 == arrayList.size()) {
                            Handler handler = new Handler();
                            handler.postDelayed(new Runnable() {
                                @Override
                                public void run() {
                                    if (isListGoingUp) {
                                        if (linearLayoutManager.findLastCompletelyVisibleItemPosition() + 1 == arrayList.size()) {
                                            Toast.makeText(MyActivity.this, "exeute something", Toast.LENGTH_SHORT).show();
                                        }
                                    }
                                }
                            }, 50);
                            //waiting for 50ms because when scrolling down from top, the variable isListGoingUp is still true until the onScrolled method is executed
                        }
                    }
                }

            }
            @Override
            public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
                super.onScrolled(recyclerView, dx, dy);

                int itemPosition = linearLayoutManager.findFirstVisibleItemPosition();


                if(isUserScrolling){
                    if (itemPosition == 0) { //  item position of uses
                        TabLayout.Tab tab = myTabLayout.getTabAt(0);
                        tab.select();
                    } else if (itemPosition == 30) {//  item position of side effects
                        TabLayout.Tab tab = myTabLayout.getTabAt(1);
                        tab.select();
                    } else if (itemPosition == 60) {//  item position of how it works
                        TabLayout.Tab tab = myTabLayout.getTabAt(2);
                        tab.select();
                    } else if (itemPosition == 90) {//  item position of precaution
                        TabLayout.Tab tab = myTabLayout.getTabAt(3);
                        tab.select();
                    }
                }



            }
        });


    }


}

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