实现fab随RecyclerView滑动隐藏显示，增加添加联系人页面，实现联系人拖动

app/src/main/java/com/ttstd/dialer/view/ItemTouchHelperCallback.java

@@ -0,0 +1,54 @@
+package com.ttstd.dialer.view;
+
+import androidx.recyclerview.widget.ItemTouchHelper;
+import androidx.recyclerview.widget.RecyclerView;
+
+import com.ttstd.dialer.adapter.ContactInfoAdapter;
+
+
+// 处理拖动和滑动事件
+public class ItemTouchHelperCallback extends ItemTouchHelper.Callback {
+    private final ContactInfoAdapter mAdapter;
+
+    public ItemTouchHelperCallback(ContactInfoAdapter adapter) {
+        mAdapter = adapter;
+    }
+
+    // 定义支持的拖动方向
+    @Override
+    public int getMovementFlags(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder) {
+        // 允许上下拖动
+        int dragFlags = ItemTouchHelper.UP | ItemTouchHelper.DOWN ;
+        // 允许左右滑动删除
+        int swipeFlags = ItemTouchHelper.START;
+        return makeMovementFlags(dragFlags, swipeFlags);
+    }
+
+    // 处理拖动交换位置
+    @Override
+    public boolean onMove(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder,
+                          RecyclerView.ViewHolder target) {
+        // 通知适配器项已移动
+        mAdapter.onItemMove(viewHolder.getAdapterPosition(), target.getAdapterPosition());
+        return true;
+    }
+
+    // 处理滑动删除
+    @Override
+    public void onSwiped(RecyclerView.ViewHolder viewHolder, int direction) {
+        // 通知适配器项已删除
+        mAdapter.onItemDismiss(viewHolder.getAdapterPosition());
+    }
+
+    // 当长按item时启用拖动
+    @Override
+    public boolean isLongPressDragEnabled() {
+        return true;
+    }
+
+    // 启用滑动删除
+    @Override
+    public boolean isItemViewSwipeEnabled() {
+        return true;
+    }
+}