如何平滑地自动滚动RecyclerView，以便用户可以看到 RecyclerView 的所有元素并从头开始再次滚动 - 就像在新闻提要等中一样。
我知道smoothScrollToPosition() 和scrollToPosition()，但它们最终会滚动到最后一个元素的速度过快。
我希望 RecyclerView 具有动画效果并缓慢移动。
【问题讨论】：
标签： android scroll android-recyclerview
只是为了稍微改进一下答案，它是自动无限滚动，动画流畅。
final int speedScroll = 1200;
final Handler handler = new Handler();
final Runnable runnable = new Runnable() {
int count = 0;
boolean flag = true;
@Override
public void run() {
if(count < adapter.getItemCount()){
if(count==adapter.getItemCount()-1){
flag = false;
}else if(count == 0){
flag = true;
}
if(flag) count++;
else count--;
recyclerView.smoothScrollToPosition(count);
handler.postDelayed(this,speedScroll);
}
}
};
handler.postDelayed(runnable,speedScroll);
这正是您的答案，但如果您链接到更流畅的动画，请使用 LayoutManager
recyclerView.setLayoutManager(new CustomLinearLayoutManager(mContext, LinearLayoutManager.HORIZONTAL, false));
控制你的动画改变 MILLISECONDS_PER_INCH 值。
public class CustomLinearLayoutManager extends LinearLayoutManager {
public CustomLinearLayoutManager(Context context) {
super(context);
}
public CustomLinearLayoutManager(Context context, int orientation, boolean reverseLayout) {
super(context, orientation, reverseLayout);
}
public CustomLinearLayoutManager(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
super(context, attrs, defStyleAttr, defStyleRes);
}
@Override
public void smoothScrollToPosition(RecyclerView recyclerView, RecyclerView.State state, int position) {
final LinearSmoothScroller linearSmoothScroller =
new LinearSmoothScroller(recyclerView.getContext()) {
private static final float MILLISECONDS_PER_INCH = 200f;
@Override
public PointF computeScrollVectorForPosition(int targetPosition) {
return CustomLinearLayoutManager.this
.computeScrollVectorForPosition(targetPosition);
}
@Override
protected float calculateSpeedPerPixel
(DisplayMetrics displayMetrics) {
return MILLISECONDS_PER_INCH / displayMetrics.densityDpi;
}
};
linearSmoothScroller.setTargetPosition(position);
startSmoothScroll(linearSmoothScroller);
}
}
【讨论】：
我认为这是最好的解决方案。
final int speedScroll = 150;
final Handler handler = new Handler();
final Runnable runnable = new Runnable() {
int count = 0;
@Override
public void run() {
if(count < list.size()){
recyclerView.scrollToPosition(count++);
handler.postDelayed(this,speedScroll);
}
}
};
handler.postDelayed(runnable,speedScroll);
【讨论】：
这是Auto Scroll RecyclerView及其100%工作的最佳方式：
RecyclerView recyclerView = findViewById(R.id.rv_id);
final int time = 4000; // it's the delay time for sliding between items in recyclerview
final Adapter adapter = new Adapter(dataItems);
recyclerView.setAdapter(adapter);
final LinearLayoutManager linearLayoutManager = new LinearLayoutManager(rootView.getContext(), LinearLayoutManager.HORIZONTAL, false);
recyclerView.setLayoutManager(linearLayoutManager);
//The LinearSnapHelper will snap the center of the target child view to the center of the attached RecyclerView , it's optional if you want , you can use it
final LinearSnapHelper linearSnapHelper = new LinearSnapHelper();
linearSnapHelper.attachToRecyclerView(recyclerView);
final Timer timer = new Timer();
timer.schedule(new TimerTask() {
@Override
public void run() {
if (linearLayoutManager.findLastCompletelyVisibleItemPosition() < (adapter.getItemCount() - 1)) {
linearLayoutManager.smoothScrollToPosition(recyclerView, new RecyclerView.State(), linearLayoutManager.findLastCompletelyVisibleItemPosition() + 1);
}
else if (linearLayoutManager.findLastCompletelyVisibleItemPosition() == (adapter.getItemCount() - 1)) {
linearLayoutManager.smoothScrollToPosition(recyclerView, new RecyclerView.State(), 0);
}
}
}, 0, time);
【讨论】：
经过反复试验，这对我来说是完美的
final RecyclerView mRecyclerViewr;
final ArrayList<String> stringArrayData = new ArrayList<String>
final LinearLayoutManager linearLayoutManager = new LinearLayoutManager(getApplicationContext(), LinearLayoutManager.HORIZONTAL, false);
mRecyclerViewr.setLayoutManager(linearLayoutManager);
CustomAdapter customAdapter = new CustomAdapter(getApplicationContext(), topPriceBarList);
mRecyclerViewr.setAdapter(customAdapter);
// Auto Scroll Left To Right
final int scrollSpeed = 100; // Scroll Speed in Milliseconds
final Handler handler = new Handler();
final Runnable runnable = new Runnable() {
int x = 15; // Pixels To Move/Scroll
boolean flag = true;
// Find Scroll Position By Accessing RecyclerView's LinearLayout's Visible Item Position
int scrollPosition = linearLayoutManager.findLastCompletelyVisibleItemPosition();
int arraySize = stringArrayData.size(); // Gets RecyclerView's Adapter's Array Size
@Override
public void run() {
if (scrollPosition < arraySize) {
if (scrollPosition == arraySize - 1) {
flag = false;
} else if (scrollPosition <= 1) {
flag = true;
}
if (!flag) {
try {
// Delay in Seconds So User Can Completely Read Till Last String
TimeUnit.SECONDS.sleep(1);
mRecyclerViewr.scrollToPosition(0); // Jumps Back Scroll To Start Point
} catch (InterruptedException e) {
e.printStackTrace();
}
}
// Know The Last Visible Item
scrollPosition = linearLayoutManager.findLastCompletelyVisibleItemPosition();
mRecyclerViewr.smoothScrollBy(x, 0);
handler.postDelayed(this, scrollSpeed);
}
}
};
handler.postDelayed(runnable, scrollSpeed);
这将自动将您的 RecyclerView 滚动到最后，等待一秒钟 (So User Can Read Till End) 并在 RecyclerView 的数组列表中跳转/滚动回第一个字符串。
如果你想在正负方向自动滚动You Just Need To Change The Condition Instead Of Using if(!flag) You Need To Set Value Of x in it
if (flag) x = 15;
else x= -15; // For Auto Scroll To Negative i.e Left Direction
【讨论】：
private void hanldeAutoScroll() {
int position=0;
final int duration = 2000;
//final int pixelsToMove = 90;
final Handler mHandler = new Handler(Looper.getMainLooper());
final Runnable SCROLLING_RUNNABLE = new Runnable() {
@Override
public void run() {
position++;
if (position<urls.size())
{
recyclerView.scrollToPosition(position);
}else if (position==urls.size())
{
position=-1;
}
// recyclerView.smoothScrollBy(pixelsToMove, 0);
mHandler.postDelayed(this, duration);
}
};
mHandler.postDelayed(SCROLLING_RUNNABLE, 2000);
}
【讨论】：
在 Kotlin 中简化：
lifecycleScope.launch(Dispatchers.Main, start = CoroutineStart.DEFAULT) {
var position = MINIMUM_POSITION
repeat(AUTO_SCROLL_REPEATING_TIMES) {
delay(SCROLL_DELAY)
rvBanners.smoothScrollToPosition(position)
when {
position+1 == listSize -> position = 0
position == 0 -> position = MINIMUM_POSITION
else -> position++
}
}
}
如果你想在特定时间开始自动滚动：
val job = lifecycleScope.launch(Dispatchers.Main, start = CoroutineStart.LAZY) {
var position = MINIMUM_POSITION
repeat(AUTO_SCROLL_REPEATING_TIMES) {
delay(SCROLL_DELAY)
rvBanners.smoothScrollToPosition(position)
when {
position+1 == listSize -> position = 0
position == 0 -> position = MINIMUM_POSITION
else -> position++
}
}
}
...
job.start()
【讨论】：
你也可以这样实现，设置recyclerview为adapter后
final int duration = 10;
final int pixelsToMove = 263;
final Handler mHandler = new Handler(Looper.getMainLooper());
final Runnable SCROLLING_RUNNABLE = new Runnable() {
@Override
public void run() {
recyclerView.smoothScrollBy(pixelsToMove, 0);
mHandler.postDelayed(this, duration);
}
};
recyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
@Override
public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
super.onScrolled(recyclerView, dx, dy);
int lastItem = horizontalLayoutManager.findLastCompletelyVisibleItemPosition();
if (lastItem == horizontalLayoutManager.getItemCount() - 1) {
mHandler.removeCallbacks(SCROLLING_RUNNABLE);
Handler postHandler = new Handler();
postHandler.postDelayed(new Runnable() {
@Override
public void run() {
quickTips.setAdapter(null);
quickTips.setAdapter(adapter);
mHandler.postDelayed(SCROLLING_RUNNABLE, 2000);
}
}, 2000);
}
}
});
mHandler.postDelayed(SCROLLING_RUNNABLE, 2000);
【讨论】：
对于平滑自动滚动，您可以使用此自定义 RecyclerView 类，您还可以在其中设置滚动时间。
public class AutoScrollRecyclerView extends RecyclerView {
private static long delayTime = 45;// How long after the interval to perform scrolling
AutoPollTask autoPollTask;// Scroll thread
private boolean running; // Is it rolling?
private boolean canRun;// Can it be automatically scrolled, depending on whether the data exceeds the screen
public AutoScrollRecyclerView(Context context) {
super(context);
}
public AutoScrollRecyclerView(Context context, @Nullable AttributeSet attrs) {
super(context, attrs);
autoPollTask = new AutoPollTask(this);// Instantiate the scroll refresh thread
}
static class AutoPollTask implements Runnable {
private final WeakReference<AutoScrollRecyclerView> mReference;
// Use weak references to hold external class references to prevent memory leaks
public AutoPollTask(AutoScrollRecyclerView reference) {
this.mReference = new WeakReference<>(reference);
}
@Override
public void run() {
AutoScrollRecyclerView recyclerView = mReference.get();// Get the recyclerview object
if (recyclerView != null && recyclerView.running && recyclerView.canRun) {
recyclerView.scrollBy(2, 2);// Note the difference between scrollBy and scrollTo
//delayed to send
recyclerView.postDelayed(recyclerView.autoPollTask, delayTime);
}
}
}
@Override
public boolean onTouchEvent(MotionEvent e) {
switch (e.getAction()) {
case MotionEvent.ACTION_DOWN:
/*if (running)
stop();*/
break;
case MotionEvent.ACTION_UP:
case MotionEvent.ACTION_CANCEL:
case MotionEvent.ACTION_OUTSIDE:
/*if (canRun)
start();*/
break;
}
return super.onTouchEvent(e);
}
//Open: If it is running, stop first -> then open
public void start() {
if (running)
stop();
canRun = true;
running = true;
postDelayed(autoPollTask, delayTime);
}
public void stop() {
running = false;
removeCallbacks(autoPollTask);
}
}
【讨论】：