Question

我有一个RecycleView。我拿一个ArrayList来获取我在mySqliteDatabase中插入的所有类别。最后我使用它的适配器将这个ArrayList设置为RecycleView。

问题：

（1）首次打开CategoryActivity。（没有类别）（2）添加第一类，第二类，第三类没有人刷新。（3）但是如果我回去，在添加第一之后。并再次参加那项活动。如果现在我插入第二个类别，那么所有 [下一个项目] 正在刷新。

我的问题是每当我插入第一类别。它成功插入但它没有显示在我的RecycleView或ArrayList [表示Recycleview not refresh]中。

但是我的主要问题是我的RecycleView不仅仅刷新My ArrayList上的 FirstCategory ..添加第一项后我的下一个所有Arraylist项目正在刷新。

以下是我的所有代码。

CategoryAdapter

public class CategoryAdapter extends RecyclerView.Adapter<CategoryAdapter.MyViewHolder> implements Filterable {

        private ArrayList<CategoryModel> dataList;

        class MyViewHolder extends RecyclerView.ViewHolder {
            TextView tvCategoryItem;

            MyViewHolder(View view) {
                super(view);
                tvCategoryItem = (TextView) view.findViewById(R.id.tvCategoryName);
            }
        }

        CategoryAdapter(ArrayList<CategoryModel> dataSet) {
            this.dataList = dataSet;
            this.filterList = dataSet;
        }

        // I used this method too. but same problem.
        void refreshAdapter(ArrayList<CategoryModel> dataSet) {
            dataList.clear();
            dataList.addAll(dataSet);
            notifyDataSetChanged();
        }

        @Override
        public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
            View itemView = LayoutInflater.from(parent.getContext())
                    .inflate(R.layout.rv_row_category_list, parent, false);

            return new MyViewHolder(itemView);
        }

        @Override
        public void onBindViewHolder(MyViewHolder holder, int position) {
            CategoryModel categoryModel = dataList.get(position);
            holder.tvCategoryItem.setText(categoryModel.getCategoryName());
        }

        @Override
        public int getItemCount() {
            return dataList.size();
        }
    }

CategoryListActivity

MyDatabase myDb;
            CategoryModel categoryModel;
            RecyclerView recyclerCategory;
            RecyclerView.LayoutManager layoutManager;
            CategoryAdapter adapter;
            ArrayList<CategoryModel> allCategory;
            int CategoryType;

            @Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_list_category);

    myDb = new MyDatabase(this);
    recyclerCategory = (RecyclerView) findViewById(R.id.recyclerCategory);

    CategoryType = CaseActivity.CategoryType;
    Log.d(GlobalConstant.KEY_CATEGORY_TYPE, "" + CategoryType);

    allCategory = myDb.getCategoryByType(CategoryType);

    if (allCategory.size() == 0) {
        Toast.makeText(this, "No Category", Toast.LENGTH_SHORT).show();
    }

    adapter = new CategoryAdapter(allCategory);
    recyclerCategory.setAdapter(adapter);
    layoutManager = new LinearLayoutManager(this);
    recyclerCategory.setLayoutManager(layoutManager);
    recyclerCategory.setItemAnimator(new DefaultItemAnimator());
    recyclerCategory.setHasFixedSize(true);

    recyclerCategory.addOnItemTouchListener(new RecyclerItemClickListener(this, recyclerCategory,
            new RecyclerItemClickListener.OnItemTouchListener() {
                @Override
                public void onItemClick(View view, int position) {
                    TextView tvCategoryItem = (TextView) view.findViewById(R.id.tvCategoryName);
                    String CategoryName = tvCategoryItem.getText().toString();

                    Intent intent = new Intent();
                    CategoryId = allCategory.get(+position).getCategoryId();
                    intent.putExtra("CategoryId", String.valueOf(CategoryId));

                    Log.e("Clicked Cat Id is ", "" + CategoryId);
                    intent.putExtra("CategoryName", CategoryName);
                    setResult(Activity.RESULT_OK, intent);
                    finish();
                }

                @Override
                public void onLongItemClick(View view, int position) {

                }
            }
    ));
}

private void openAlert() {
    final EditText etCategoryName = new EditText(this);

    CustomAlertDialog dialog1 = new CustomAlertDialog(this);
    dialog1.setTitle("Add Category");
    dialog1.setView(etCategoryName);
    dialog1.setCancelable(true);

    dialog1.setPositiveButton("Add", new DialogInterface.OnClickListener() {
        @Override
        public void onClick(DialogInterface dialogInterface, int i) {
            final String CategoryName = etCategoryName.getText().toString().trim();
            final String storedCategoryName = myDb.ExistCategory(CategoryName);

            if (CategoryName.equals("") && CategoryName.length() == 0) {
                Builder builder1 = GlobalConstant.createAlert(CategoryListActivity.this, "Warning", "Enter Category Name");
                builder1.setPositiveButton("Back", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialogInterface, int i) {
                        dialogInterface.dismiss();
                    }
                });
            } else {
                if (CategoryName.equals(storedCategoryName)) {
                    Builder builder1 = GlobalConstant.createAlert(CategoryListActivity.this, "Warning", "Category Already Exists");
                    builder1.setPositiveButton("Back", new DialogInterface.OnClickListener() {
                        @Override
                        public void onClick(DialogInterface dialogInterface, int i) {
                            dialogInterface.dismiss();
                        }
                    });
                } else {
                    dialogInterface.dismiss();

                    categoryModel = new CategoryModel(CategoryName, String.valueOf(CategoryType));

                    myDb.createCategory(categoryModel);

                    Toast.makeText(CategoryListActivity.this, "CategoryName " + CategoryName
                            + "\nCategoryType " + CategoryType, Toast.LENGTH_SHORT).show();


                    allCategory.clear();

                    allCategory = myDb.getCategoryByType(CategoryType);

                    adapter.notifyDataSetChanged();

                }
            }
        }
    });
    dialog1.show();
}

        @Override
        public boolean onOptionsItemSelected(MenuItem item) {
            switch (item.getItemId()) {
                case R.id.action_add:
                    openAlert();
                default:
                    return super.onOptionsItemSelected(item);
            }
        }
    }

我的 createCategory（）方法。

public long createCategory(CategoryModel categoryModel) {
        SQLiteDatabase db = this.getWritableDatabase();
        ContentValues values = new ContentValues();

        values.put(CATEGORY_NAME, categoryModel.getCategoryName());
        values.put(CATEGORY_TYPE, categoryModel.getCategoryType());

        long CategoryId = db.insert(TABLE_CATEGORY, null, values);
        db.close();
        return CategoryId;
    }

以及我的数据库上的 getCategoryByType（）方法。

public ArrayList<CategoryModel> getCategoryByType(int CategoryType) {
        ArrayList<CategoryModel> Categories = new ArrayList<>();
        // String selectQuery = "SELECT " + CATEGORY_NAME + " FROM " + TABLE_CATEGORY + " WHERE " + CATEGORY_TYPE + " = " + CategoryType;
        String selectQuery = "SELECT * FROM " + TABLE_CATEGORY + " WHERE " + CATEGORY_TYPE + " = " + CategoryType + " ORDER BY CategoryId DESC";
        Log.e(DB_LOG, selectQuery);
        SQLiteDatabase db = this.getReadableDatabase();

        Cursor cursor = db.rawQuery(selectQuery, null);
        if (cursor != null && cursor.getCount() > 0) {
            if (cursor.moveToFirst()) {
                do {
                    CategoryModel categoryModel = new CategoryModel();

                    categoryModel.setCategoryId(cursor.getInt(cursor.getColumnIndex(CATEGORY_ID)));
                    categoryModel.setCategoryName(cursor.getString(cursor.getColumnIndex(CATEGORY_NAME)));
                    categoryModel.setCategoryType(cursor.getString(cursor.getColumnIndex(CATEGORY_TYPE)));

                    Categories.add(categoryModel);
                } while (cursor.moveToNext());
            }
            cursor.close();
        }
        return Categories;
    }

任何类型的帮助，建议都得到很多赞赏.....提前致谢

下面是添加First Item后的屏幕截图。

First Item Inserted but not shown in RecycleView

我的LogCat截图如下。

Logcat Screenshot

Answer 1

更改您的活动onCreate：

@Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_list_category);

        myDb = new MyDatabase(this);
        recyclerCategory = (RecyclerView) findViewById(R.id.recyclerCategory);

        CategoryType = CaseActivity.CategoryType;
        Log.d(GlobalConstant.KEY_CATEGORY_TYPE, "" + CategoryType);
        allCategory = new ArrayList<>();
        adapter = new CategoryAdapter(allCategory);
        layoutManager = new LinearLayoutManager(this);
        recyclerCategory.setLayoutManager(layoutManager);
        recyclerCategory.setItemAnimator(new DefaultItemAnimator());
        recyclerCategory.setHasFixedSize(true);
        recyclerCategory.setAdapter(adapter);

        allCategory = myDb.getCategoryByType(CategoryType);
        adapter.notifyDataSetChange();

        if (allCategory.size() == 0) {

            Toast.makeText(this, "No Category", Toast.LENGTH_SHORT).show();
        }    
    }

并在 setPositiveButton 内，替换

adapter = new CategoryAdapter(allCategory);
recyclerCategory.setAdapter(adapter);

adapter.notifyDataSetChanged();

带

adapter.notifyDataSetChanged();

同时替换

allCategory = myDb.getCategoryByType(CategoryType);

与

allCategory.addAll(myDb.getCategoryByType(CategoryType));

尝试再次运行程序。

Answer 2

以这种方式更改onCreate

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_list_category);

    myDb = new MyDatabase(this);
    recyclerCategory = (RecyclerView) findViewById(R.id.recyclerCategory);

     CategoryType = CaseActivity.CategoryType;
     Log.d(GlobalConstant.KEY_CATEGORY_TYPE, "" + CategoryType);

     allCategory = myDb.getCategoryByType(CategoryType);

     if (allCategory.size() == 0) {
         Toast.makeText(this, "No Category", Toast.LENGTH_SHORT).show();
    }    

    adapter = new CategoryAdapter(allCategory);
    recyclerCategory.setAdapter(adapter);
    layoutManager = new LinearLayoutManager(this);
    recyclerCategory.setLayoutManager(layoutManager);
    recyclerCategory.setItemAnimator(new DefaultItemAnimator());
    recyclerCategory.setHasFixedSize(true);
}

现在您可以使用adapter.notifyDataSetChanged();而不重新设置adapter并将其设置为RecyclerView

如果您进入setPositiveButton allCategory = myDb.getCategoryByType(CategoryType);，那么您对allCategory的引用就会丢失。

你需要

allCategory.clear();
allCategory.addAll(myDb.getCategoryByType(CategoryType));

使用Alertdialog插入项目后，RecyclerView不会刷新

2 个答案: