问题
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.
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.
Here when 'How it works' appears below TabLayout then tabs 'How it works' should be highlighted.
回答1:
Try this
follow this steps
- Add a
ScrollListenerto yourRecyclerView - than find first visible item of your
RecyclerView - set the select the tab in
TabLayoutas per position of yourRecyclerView
SAMPLE CODE
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();
}
}
});
EDIT
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();
}
}
}
});
}
}
回答2:
private fun syncTabWithRecyclerView() {
// Move recylerview to the position selected by user
menutablayout.addOnTabSelectedListener(object : TabLayout.OnTabSelectedListener {
override fun onTabSelected(tab: TabLayout.Tab) {
if (!isUserScrolling) {
val position = tab.position
linearLayoutManager.scrollToPositionWithOffset(position, 0)
}
}
override fun onTabUnselected(tab: TabLayout.Tab) {
}
override fun onTabReselected(tab: TabLayout.Tab) {
}
})
// Detect recyclerview position and select tab respectively.
menuRecyclerView.addOnScrollListener(object : RecyclerView.OnScrollListener() {
override fun onScrollStateChanged(recyclerView: RecyclerView, newState: Int) {
if (newState == RecyclerView.SCROLL_STATE_DRAGGING) {
isUserScrolling = true
} else if (newState == RecyclerView.SCROLL_STATE_IDLE)
isUserScrolling = false
}
}
override fun onScrolled(recyclerView: RecyclerView, dx: Int, dy: Int) {
super.onScrolled(recyclerView, dx, dy)
if (isUserScrolling) {
val itemPosition = linearLayoutManager.findLastVisibleItemPosition()
val tab = menutablayout.getTabAt(itemPosition)
tab?.select()
}
}
})
}
来源：https://stackoverflow.com/questions/51701488/how-to-sync-tablayout-with-recyclerview