这是我在Logcat中得到的：

E/ROOM: Invalidation tracker is initialized twice :/.

E/Itemmoved: Counterfrom3

next item:to2

在onCreate中初始化数据库.

db = Room.databaseBuilder(getApplicationContext(),AppDatabase.class,DB_NAME)
                .fallbackToDestructiveMigration()
                .allowMainThreadQueries()
                .build();

RecyclerView适配器代码.

@Override
public boolean onItemMove(int fromPosition,int toPosition) {
    String name = dataSet.get(fromPosition).getName();
    //this will make "Add item" do not move from its first position..
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
        if (!(Objects.equals(name,"Add") || (toPosition == 0 && fromPosition == 1))) {
            Collections.swap(dataSet,fromPosition,toPosition);
            MoveItem(fromPosition,toPosition);
            notifyItemMoved(fromPosition,toPosition);
            return true;
        }
    }
    return false;
}

移动项目时更新数据的代码.

public static void MoveItem(int fromPosition,int toPosition){
        String name = data.get(fromPosition).getName(); //This gets the current item name in the view 
        String nexName = data.get(toPosition).getName(); //This gets the next item name in the view 

        ContentValues fromContentValues = new ContentValues();
        fromContentValues.put("posItem",toPosition); //adding data to ContentValues
        ContentValues toContentValues = new ContentValues();
        toContentValues.put("posItem",fromPosition);
        Log.e("Item moved",name + "from" + fromPosition + "\n" + "next item:" + "to" + toPosition);

        db.beginTransaction();
        try {
        db.getOpenHelper().getWritableDatabase().update(name,fromContentValues,"posItem =" + fromPosition,null);

        db.getOpenHelper().getWritableDatabase().update(nexName,toContentValues,"posItem =" + toPosition,null);
        db.setTransactionSuccessful(); //setting Transaction Successful
        } finally {
            db.endTransaction(); // commit or rollback
            db.close(); //closing database
        }
    }