RecyclerView滚动到底部监听

xiaoxiao2021-02-28  12

public class OnRecyclerViewScrollListener extends RecyclerView.OnScrollListener implements OnBottomListener { public enum LAYOUT_MANAGER_TYPE { LINEAR, GRID, STAGGERED_GRID } /** * layoutManager的类型(枚举) */ protected LAYOUT_MANAGER_TYPE layoutManagerType; /** * 最后一个的位置 */ private int[] lastPositions; /** * 最后一个可见的item的位置 */ private int lastVisibleItemPosition; /** * 当前滑动的状态 */ private int currentScrollState = 0; @Override public void onScrolled(RecyclerView recyclerView, int dx, int dy) { super.onScrolled(recyclerView, dx, dy); RecyclerView.LayoutManager layoutManager = recyclerView.getLayoutManager(); if (layoutManagerType == null) { if (layoutManager instanceof LinearLayoutManager) { layoutManagerType = LAYOUT_MANAGER_TYPE.LINEAR; } else if (layoutManager instanceof GridLayoutManager) { layoutManagerType = LAYOUT_MANAGER_TYPE.GRID; } else if (layoutManager instanceof StaggeredGridLayoutManager) { layoutManagerType = LAYOUT_MANAGER_TYPE.STAGGERED_GRID; } else { throw new RuntimeException("Unsupported LayoutManager used. Valid ones are LinearLayoutManager, GridLayoutManager and StaggeredGridLayoutManager"); } } switch (layoutManagerType) { case LINEAR: lastVisibleItemPosition = ((LinearLayoutManager) layoutManager).findLastVisibleItemPosition(); break; case GRID: lastVisibleItemPosition = ((GridLayoutManager) layoutManager).findLastVisibleItemPosition(); break; case STAGGERED_GRID: StaggeredGridLayoutManager staggeredGridLayoutManager = (StaggeredGridLayoutManager) layoutManager; if (lastPositions == null) { lastPositions = new int[staggeredGridLayoutManager.getSpanCount()]; } staggeredGridLayoutManager.findLastVisibleItemPositions(lastPositions); lastVisibleItemPosition = findMax(lastPositions); break; } } @Override public void onScrollStateChanged(RecyclerView recyclerView, int newState) { super.onScrollStateChanged(recyclerView, newState); currentScrollState = newState; RecyclerView.LayoutManager layoutManager = recyclerView.getLayoutManager(); int visibleItemCount = layoutManager.getChildCount(); int totalItemCount = layoutManager.getItemCount(); if ((visibleItemCount > 0 && currentScrollState == RecyclerView.SCROLL_STATE_IDLE && (lastVisibleItemPosition) >= totalItemCount - 1)) { onBottom(); } } @Override public void onBottom() { // Log.d(TAG, "滑动到了底部"); } private int findMax(int[] lastPositions) { int max = lastPositions[0]; for (int value : lastPositions) { if (value > max) { max = value; } } return max; } } public interface OnBottomListener { void onBottom(); }
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