1 問題

在RecycleView里面實現指定位置的拖動效果，（這里是實現線性布局的，不是網格布局的）

@Override public boolean onMove(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, RecyclerView.ViewHolder target) { Log.i(TAG, 'onMove viewHolder.getAdapterPosition() is:' + viewHolder.getAdapterPosition()); int itemViewType = viewHolder.getAdapterPosition(); Log.i(TAG, 'onMove---------------------------------itemViewType is:' + itemViewType);// if (itemViewType == 0 || itemViewType == 1 || itemViewType == 16) {// Log.i(TAG, 'onMove---------------------------------itemViewType is:' + itemViewType);// return false;// } int fromPosition = viewHolder.getAdapterPosition();//得到拖動ViewHolder的position int toPosition = target.getAdapterPosition();//得到目標ViewHolder的position Log.i(TAG, 'onMove---------------------------------fromPosition is:' + fromPosition); Log.i(TAG, 'onMove---------------------------------toPosition is:' + toPosition);//這里的position如果不是指定范圍內的話，直接返回false，就拖動不到其它位置了 if (DragUtil.INSTANCE.getProhibitDragIndexs().contains(toPosition)) { return false; } itemTouchAdapter.onMove(fromPosition,toPosition); return true; }

2 關鍵代碼如下

MyItemTouchCallback.java

import android.graphics.Canvas;import android.graphics.Color;import android.graphics.drawable.Drawable;import android.util.Log; import androidx.recyclerview.widget.GridLayoutManager;import androidx.recyclerview.widget.ItemTouchHelper;import androidx.recyclerview.widget.RecyclerView; import com.appsinnova.android.keepdrop.manager.FileScanManager; /** * Created by Administrator on 2016/4/12. */public class MyItemTouchCallback extends ItemTouchHelper.Callback { public static final String TAG = MyItemTouchCallback.class.getSimpleName(); private ItemTouchAdapter itemTouchAdapter; public MyItemTouchCallback(ItemTouchAdapter itemTouchAdapter){ this.itemTouchAdapter = itemTouchAdapter; } @Override public boolean isLongPressDragEnabled() { return false; } @Override public boolean isItemViewSwipeEnabled() { return true; } @Override public int getMovementFlags(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder) { Log.i(TAG, 'getMovementFlags viewHolder.getAdapterPosition() is:' + viewHolder.getAdapterPosition()); int itemViewType = viewHolder.getAdapterPosition(); Log.i(TAG, '---------------------------------itemViewType is:' + itemViewType);// if (itemViewType == 0 || itemViewType == 1 || itemViewType == 16) {// Log.i(TAG, '-getMovementFlags--------------------------------itemViewType is:' + itemViewType);// return makeMovementFlags(0, 0);// } if (recyclerView.getLayoutManager() instanceof GridLayoutManager) { final int dragFlags = ItemTouchHelper.UP | ItemTouchHelper.DOWN | ItemTouchHelper.LEFT | ItemTouchHelper.RIGHT; final int swipeFlags = 0; return makeMovementFlags(dragFlags, swipeFlags); } else { final int dragFlags = ItemTouchHelper.UP | ItemTouchHelper.DOWN; //final int swipeFlags = ItemTouchHelper.START | ItemTouchHelper.END; final int swipeFlags = 0; Log.i(TAG, 'makeMovementFlags start'); return makeMovementFlags(dragFlags, swipeFlags); } } @Override public boolean onMove(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, RecyclerView.ViewHolder target) { Log.i(TAG, 'onMove viewHolder.getAdapterPosition() is:' + viewHolder.getAdapterPosition()); int itemViewType = viewHolder.getAdapterPosition(); Log.i(TAG, 'onMove---------------------------------itemViewType is:' + itemViewType);// if (itemViewType == 0 || itemViewType == 1 || itemViewType == 16) {// Log.i(TAG, 'onMove---------------------------------itemViewType is:' + itemViewType);// return false;// } int fromPosition = viewHolder.getAdapterPosition();//得到拖動ViewHolder的position int toPosition = target.getAdapterPosition();//得到目標ViewHolder的position Log.i(TAG, 'onMove---------------------------------fromPosition is:' + fromPosition); Log.i(TAG, 'onMove---------------------------------toPosition is:' + toPosition);//這里的position如果不是指定范圍內的話，直接返回false，就拖動不到其它位置了 if (DragUtil.INSTANCE.getProhibitDragIndexs().contains(toPosition)) { return false; } itemTouchAdapter.onMove(fromPosition,toPosition); return true; } @Override public void onSwiped(RecyclerView.ViewHolder viewHolder, int direction) { int position = viewHolder.getAdapterPosition(); itemTouchAdapter.onSwiped(position); } @Override public void onChildDraw(Canvas c, RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, float dX, float dY, int actionState, boolean isCurrentlyActive) { if (actionState == ItemTouchHelper.ACTION_STATE_SWIPE) { //滑動時改變Item的透明度 final float alpha = 1 - Math.abs(dX) / (float) viewHolder.itemView.getWidth(); viewHolder.itemView.setAlpha(alpha); viewHolder.itemView.setTranslationX(dX); } else { super.onChildDraw(c, recyclerView, viewHolder, dX, dY, actionState, isCurrentlyActive); } } @Override public void onSelectedChanged(RecyclerView.ViewHolder viewHolder, int actionState) { if (actionState != ItemTouchHelper.ACTION_STATE_IDLE) { if (background == null && bkcolor == -1) {Drawable drawable = viewHolder.itemView.getBackground();if (drawable == null) { bkcolor = 0;} else { background = drawable;} } viewHolder.itemView.setBackgroundColor(Color.LTGRAY); } super.onSelectedChanged(viewHolder, actionState); } @Override public void clearView(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder) { super.clearView(recyclerView, viewHolder); viewHolder.itemView.setAlpha(1.0f); if (background != null) viewHolder.itemView.setBackgroundDrawable(background); if (bkcolor != -1) viewHolder.itemView.setBackgroundColor(bkcolor); //viewHolder.itemView.setBackgroundColor(0); if (onDragListener!=null){ onDragListener.onFinishDrag(); } } private Drawable background = null; private int bkcolor = -1; private OnDragListener onDragListener; public MyItemTouchCallback setOnDragListener(OnDragListener onDragListener) { this.onDragListener = onDragListener; return this; } public interface OnDragListener{ void onFinishDrag(); } public interface ItemTouchAdapter { void onMove(int fromPosition, int toPosition); void onSwiped(int position); }}

OnRecyclerItemClickListener.java

import android.view.GestureDetector;import android.view.MotionEvent;import android.view.View; import androidx.core.view.GestureDetectorCompat;import androidx.recyclerview.widget.RecyclerView; /** * Created by Administrator on 2016/4/14. */public class OnRecyclerItemClickListener implements RecyclerView.OnItemTouchListener { private GestureDetectorCompat mGestureDetector; private RecyclerView recyclerView; public OnRecyclerItemClickListener(RecyclerView recyclerView){ this.recyclerView = recyclerView; mGestureDetector = new GestureDetectorCompat(recyclerView.getContext(),new ItemTouchHelperGestureListener()); } @Override public boolean onInterceptTouchEvent(RecyclerView rv, MotionEvent e) { mGestureDetector.onTouchEvent(e); return false; } @Override public void onTouchEvent(RecyclerView rv, MotionEvent e) { mGestureDetector.onTouchEvent(e); } @Override public void onRequestDisallowInterceptTouchEvent(boolean disallowIntercept) { } private class ItemTouchHelperGestureListener extends GestureDetector.SimpleOnGestureListener { @Override public boolean onSingleTapUp(MotionEvent e) { View child = recyclerView.findChildViewUnder(e.getX(), e.getY()); if (child!=null) {RecyclerView.ViewHolder vh = recyclerView.getChildViewHolder(child);onItemClick(vh); } return true; } @Override public void onLongPress(MotionEvent e) { View child = recyclerView.findChildViewUnder(e.getX(), e.getY()); if (child!=null) {RecyclerView.ViewHolder vh = recyclerView.getChildViewHolder(child);onLongClick(vh); } } } public void onLongClick(RecyclerView.ViewHolder vh){} public void onItemClick(RecyclerView.ViewHolder vh){}}

適配器里面實現接口

MyItemTouchCallback.ItemTouchAdapter

import android.text.TextUtils;import android.util.Log;import android.view.View;import android.widget.ImageView; import org.greenrobot.eventbus.EventBus; import java.util.ArrayList;import java.util.Collections;import java.util.List; import static com.appsinnova.android.keepdrop.recommend.entity.ChannelHead.channelType; public class ChannelManagerAdapter extends BaseMultiItemQuickAdapter<MultiItemEntity, BaseViewHolder> implements MyItemTouchCallback.ItemTouchAdapter { public static final String TAG = ChannelManagerAdapter.class.getSimpleName(); public static final int MY_VEDIO_TYPE = 0; public static final int MORE_VEDIO_TYPE = 1; public static final int CAN_EDITABLE = 1; public static final int CAN_NOT_EDITABLE = 0; public List<MultiItemEntity> results = null; public ChannelManagerAdapter(List<MultiItemEntity> data) { super(data); addItemType(ChannelHead.channelHeadType, R.layout.item_channel_head); addItemType(channelType, R.layout.item_channel); this.results = data; } @Override protected void convert(BaseViewHolder helper, MultiItemEntity item) { switch (helper.getItemViewType()) { } } @Override public void onMove(int fromPosition, int toPosition) { if (fromPosition==results.size()-1 || toPosition==results.size()-1){ return; } if (fromPosition < toPosition) { for (int i = fromPosition; i < toPosition; i++) {Collections.swap(results, i, i + 1); } } else { for (int i = fromPosition; i > toPosition; i--) {Collections.swap(results, i, i - 1); } }//這個數據是移動后的數據，會更新原始數據 int size = results.size(); List<RecommendVedioModel.RecommendVedioItem> items = new ArrayList<RecommendVedioModel.RecommendVedioItem>(); RecommendVedioModel recommendVedioModel = SPHelper.getInstance().getObject(SpConstants.RECOMMEND_VEDIO_CATETGORY, RecommendVedioModel.class); for (int i = 0; i < size; ++i) { if (results.get(i).getItemType() == channelType) {RecommendVedioModel.RecommendVedioItem item = (RecommendVedioModel.RecommendVedioItem)results.get(i);items.add(item); } } if (recommendVedioModel != null) { recommendVedioModel.items = items; } else { Log.i(TAG, 'recommendVedioModel is null'); } SPHelper.getInstance().putObject(SpConstants.RECOMMEND_VEDIO_CATETGORY, recommendVedioModel); notifyItemMoved(fromPosition, toPosition); } @Override public void onSwiped(int position) { }}

然后在頁面顯示的地方

channelManagerAdapter = ChannelManagerAdapter(allDatas) val layoutManager = LinearLayoutManager(this) layoutManager.orientation = LinearLayoutManager.VERTICAL channelRecycleview.setLayoutManager(layoutManager) channelRecycleview.setAdapter(channelManagerAdapter) val itemTouchHelper = ItemTouchHelper(MyItemTouchCallback(channelManagerAdapter)) itemTouchHelper.attachToRecyclerView(channelRecycleview) channelRecycleview.addOnItemTouchListener(object : OnRecyclerItemClickListener(channelRecycleview) { override fun onLongClick(vh: RecyclerView.ViewHolder) {LogUtil.i(TAG, 'onLongClick vh.layoutPosition is：' + vh.layoutPosition)var index = vh.layoutPositionif (!prohibitDragIndexs.contains(index)) { itemTouchHelper.startDrag(vh)} } })

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