我如何解析我试图传递给我试图从 sqlite 游标中提取的 cardviewadapter 的变量

Question

ide 告诉我它无法解析我放入 ProjectsCardAdapter 参数中的符号。符号是变量 inside 一个 try 块，其中包含来自 cursor

的字符串类型

我试图在 try 块之外初始化字符串数组变量ide，但意识到我需要获取游标将有多少行来初始化字符串数组。

public class ProjectsFragment extends Fragment {

    public ProjectsFragment() {
        // Required empty public constructor
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        RecyclerView projectsRecycler = (RecyclerView) inflater.inflate(
                R.layout.fragment_projects, container, false);

        try {
            SQLiteOpenHelper projectsDBhelper = new ProjectsDBhelper(inflater.getContext());
            SQLiteDatabase db = projectsDBhelper.getReadableDatabase();
            Cursor cursor = db.query("PROJECTS",
                    new String[]{"PROJ_STAGE", "PROJ_BUDGET", "PROJ_LOC", "CLIENT_NAME"}
                    , null
                    , null, null, null, null);

            int rowCount = cursor.getCount();
            String[] projStage = new String[rowCount];
            String[] projBudget = new String[rowCount];
            String[] projLoc = new String[rowCount];
            String[] clientName = new String[rowCount];
            int i = 0;
            Float floatBudget;

            if (cursor.moveToFirst()) {

                projStage[i] = cursor.getString(0);
                floatBudget = cursor.getFloat(1);
                projLoc[i] = cursor.getString(2);
                clientName[i] = cursor.getString(3);

                projBudget[i] = String.format("%,.2f", floatBudget.toString());

            cursor.close();
            db.close();

        } catch (SQLiteException e) {

            Toast exceptionToast = Toast.makeText(inflater.getContext(), "Database unavailable", Toast.LENGTH_SHORT);
            exceptionToast.show();

        }
        //This is the ProjectsCardAdapter that couldnt resolve the symbol
        ProjectsCardAdapter projectsCardAdapter = new ProjectsCardAdapter(projStage, projBudget, projLoc, clientName);
        projectsRecycler.setAdapter(projectsCardAdapter);
        LinearLayoutManager layoutManager = new LinearLayoutManager(getActivity());
        projectsRecycler.setLayoutManager(layoutManager);
        return projectsRecycler;
    }
}

我想使用来自 SQLite 的数据测试显示一组文本的卡片视图，但适配器无法从游标中获取变量

Answer 1

您的问题是 projStage、projBudget、projLoc 和 clientName 在 try 块中声明，因此仅在 try 块中具有范围。

以下内容会将范围扩大到 onCreateView 方法内：-

public class ProjectsFragment extends Fragment {

    public ProjectsFragment() {
        // Required empty public constructor
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        RecyclerView projectsRecycler = (RecyclerView) inflater.inflate(
                R.layout.fragment_projects, container, false);
        String[] projStage;
        String[] projBudget;
        String[] projLoc;
        String[] clientName;

        try {
            SQLiteOpenHelper projectsDBhelper = new ProjectsDBhelper(inflater.getContext());
            SQLiteDatabase db = projectsDBhelper.getReadableDatabase();
            Cursor cursor = db.query("PROJECTS",
                    new String[]{"PROJ_STAGE", "PROJ_BUDGET", "PROJ_LOC", "CLIENT_NAME"}
                    , null
                    , null, null, null, null);

            int rowCount = cursor.getCount();
            projStage = new String[rowCount];
            projBudget = new String[rowCount];
            projLoc = new String[rowCount];
            clientName = new String[rowCount];
            int i = 0;
            Float floatBudget;

            if (cursor.moveToFirst()) {
                projStage[i] = cursor.getString(0);
                floatBudget = cursor.getFloat(1);
                projLoc[i] = cursor.getString(2);
                clientName[i] = cursor.getString(3);
                projBudget[i] = String.format("%,.2f", floatBudget.toString());

            cursor.close();
            db.close();

        } catch (SQLiteException e) {

            Toast exceptionToast = Toast.makeText(inflater.getContext(), "Database unavailable", Toast.LENGTH_SHORT);
            exceptionToast.show();

        }
        //This is the ProjectsCardAdapter that couldnt resolve the symbol
        ProjectsCardAdapter projectsCardAdapter = new ProjectsCardAdapter(projStage, projBudget, projLoc, clientName);
        projectsRecycler.setAdapter(projectsCardAdapter);
        LinearLayoutManager layoutManager = new LinearLayoutManager(getActivity());
        projectsRecycler.setLayoutManager(layoutManager);
        return projectsRecycler;
    }
}

注意，这是原理代码。该代码尚未经过测试或运行，因此可能包含错误。

我如何解析我试图传递给我试图从 sqlite 游标中提取的 cardviewadapter 的变量

How can i resolve the variable i was trying to pass to a cardviewadapter that i tried to extract from sqlite cursor

android-fragments

android-sqlite

android-cardview

sqliteopenhelper