Java 来自本地数据存储的Android解析查询太慢

在我的主要活动中，我用字符串数组填充recyclerview；但是，我从我的解析数据库中获取这些字符串

我现在知道，当您查询信息时，该方法是异步的，这意味着它在后台运行，等待从数据库接收响应，同时代码继续运行。我遇到了这样一个问题：用字符串填充数组花费的时间太长，并且recycerview已经被填充（因为数组还没有被填充，所以使用空值）

因此，我决定使用parse在本地保存数据，并使用数据库备份信息。我的问题仍然是，这太慢了，无法为recyclerview填充我的适配器。我甚至确保它没有查询数据库，并将我的数据和互联网连接转到我正在测试的手机上。这是同一个故事

是否有人知道一种优化的方法来检索数据，以便它足够快地填充recyclerview，因为现在获取字符串需要整整3秒钟。我不想暂停我的程序3秒钟，只是为了等待解析完成它的工作

下面是我如何保存数据的

// get current user
ParseObject studentClasses = new ParseObject("StudentClasses");

// register their periods into database
studentClasses.put("student_id", ParseUser.getCurrentUser());
studentClasses.put("first_period", ClassSelected_Period[PERIOD1]);
studentClasses.put("second_period", ClassSelected_Period[PERIOD2]);
studentClasses.put("third_period", ClassSelected_Period[PERIOD3]);
studentClasses.put("fourth_period", ClassSelected_Period[PERIOD4]);
studentClasses.put("fifth_period", ClassSelected_Period[PERIOD5]);
studentClasses.put("sixth_period", ClassSelected_Period[PERIOD6]);
studentClasses.put("seventh_period", ClassSelected_Period[PERIOD7]);

// save the information locally and in database
studentClasses.pinInBackground();

// navigate user home
navigateToHome();

下面是我如何检索主要活动中的数据

// query database for user's classes
ParseQuery<ParseObject> query = ParseQuery.getQuery("StudentClasses");
query.fromLocalDatastore().whereEqualTo("student_id", ParseUser.getCurrentUser());

// find it, first looking at local data store then going to database
query.getFirstInBackground(new GetCallback<ParseObject>()
{
    @Override
    public void done (ParseObject parseObject, ParseException e)
    {
        if (e == null)
        {
            // retrieved the object
            userClasses[PERIOD1] = parseObject.getString("first_period");
            userClasses[PERIOD2] = parseObject.getString("second_period");
            userClasses[PERIOD3] = parseObject.getString("third_period");
            userClasses[PERIOD4] = parseObject.getString("fourth_period");
            userClasses[PERIOD5] = parseObject.getString("fifth_period");
            userClasses[PERIOD6] = parseObject.getString("sixth_period");
            userClasses[PERIOD7] = parseObject.getString("seventh_period");

            // DEBUG: shows how long it takes for method to return
            Toast.makeText(getApplicationContext(),"during call = " + userClasses[PERIOD1], Toast.LENGTH_LONG).show();
        }
        else
        {
            // DEBUG: shows if exception happened
            Toast.makeText(getApplicationContext(),"Exception Thrown" ,Toast.LENGTH_SHORT).show();
        }
    }
});

// DEBUG: shows how long it takes for code to reach this point
Toast.makeText(getApplicationContext(),"after call = " + userClasses[PERIOD1], Toast.LENGTH_LONG).show();

    package maxbleggi.afstudentplanner;

import ... 

public class MainActivity extends AppCompatActivity
{
    // "MACROS" for user's class periods
    private final int PERIOD1 = 0;
    private final int PERIOD2 = 1;
    private final int PERIOD3 = 2;
    private final int PERIOD4 = 3;
    private final int PERIOD5 = 4;
    private final int PERIOD6 = 5;
    private final int PERIOD7 = 6;

    // toolbar
    private Toolbar toolbar;

    // navigation drawer
    private DrawerLayout navDrawer;

    // user's data
     public String[] userClasses = new String[10];

    // list to fill Classroom class with
    private List<ClassroomClass> classrooms;

    /*
    * on creation of activity
     */
    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        // initialise and set toolbar as actionbar
        toolbar = (Toolbar) findViewById(R.id.tool_bar);
        setSupportActionBar(toolbar);

        // initialize nav bars
        initNavBars();

        // initialize drawer layout
        NavigationView navView = (NavigationView) findViewById(R.id.navigation_view);

        // initialize nav drawer
        navDrawer = (DrawerLayout) findViewById(R.id.drawer);
        initNavDrawer(navDrawer);

        // initialize layout manager for recycler view
        RecyclerView.LayoutManager mainLayoutManager = new LinearLayoutManager(this);

        // initialize data for all classes before setting adapter
        initClassData();

        // set the adapter for recycler view
        RecyclerView.Adapter mainAdapter = new MainRecyclerAdapter(classrooms);

        // initialize recycler view elements
        RecyclerView mainRecyclerView = (RecyclerView) findViewById(R.id.main_recycler_view);

        // add layout manager to recycler view
        mainRecyclerView.setLayoutManager(mainLayoutManager);

        // add adapter to recycler view
        mainRecyclerView.setAdapter(mainAdapter);
    }

    /*
    * initializes the class data for each class
    */
    public void initClassData()
    {
        // check if a user is not cached
        ParseUser currentUser = ParseUser.getCurrentUser();
        if (currentUser == null)
        {
            // prompt user to Register screen
            // create intent to start activity
            Intent intent = new Intent(MainActivity.this, RegisterActivity.class);
            intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);

            // start new activity
            startActivity(intent);

            // stop current activity
            finish();
        }

        // query database for user's classes
        ParseQuery<ParseObject> query = ParseQuery.getQuery("StudentClasses");
        query.fromLocalDatastore().whereEqualTo("student_id", ParseUser.getCurrentUser());

        // find it, first looking at local data store then going to database
        query.getFirstInBackground(new GetCallback<ParseObject>()
        {
            @Override
            public void done (ParseObject parseObject, ParseException e)
            {
                if (e == null)
                {
                    // retrieved the object
                    userClasses[PERIOD1] = parseObject.getString("first_period");
                    userClasses[PERIOD2] = parseObject.getString("second_period");
                    userClasses[PERIOD3] = parseObject.getString("third_period");
                    userClasses[PERIOD4] = parseObject.getString("fourth_period");
                    userClasses[PERIOD5] = parseObject.getString("fifth_period");
                    userClasses[PERIOD6] = parseObject.getString("sixth_period");
                    userClasses[PERIOD7] = parseObject.getString("seventh_period");

                    // DEBUG: shows how long it takes for method to return
                    Toast.makeText(getApplicationContext(),"during call = " + userClasses[PERIOD1], Toast.LENGTH_LONG).show();
                }
                else
                {
                    // DEBUG: shows if exception happened
                    Toast.makeText(getApplicationContext(),"Exception Thrown" ,Toast.LENGTH_SHORT).show();
                }
            }
        });

        // DEBUG: shows how long it takes for code to reach this point
        Toast.makeText(getApplicationContext(),"after call = " + userClasses[PERIOD1], Toast.LENGTH_LONG).show();

        // fill all fields for class periods
        classrooms = new ArrayList<>();

        // titles of classes to add to list
        String[] classTitles = {"First Period", "Second Period", "Third Period", "Fourth Period",
                "Fifth Period", "Sixth Period", "Seventh Period"};

            // iterate over every period to add it to the list
            for (int i = 0; i <= PERIOD7; i++)
            {
                // if there was a class registered for that period
                if (userClasses[PERIOD3] != null)
                {
                    // add it to the class to be added to recycler view
                    classrooms.add(new ClassroomClass(userClasses[i], classTitles[i], i + 1));
                }
            }

    }

    /*
    * initialize navigation drawer
     */
    public void initNavDrawer(final DrawerLayout navDrawer)
    {
        final NavigationView navView = (NavigationView) findViewById(R.id.navigation_view);

        navView.setNavigationItemSelectedListener(new NavigationView.OnNavigationItemSelectedListener()
        {
            @Override
            public boolean onNavigationItemSelected(MenuItem menuItem)
            {
                menuItem.setChecked(true);
                navDrawer.closeDrawers();
                return true;
            }
        });
    }

    /*
    * initialize navigation bars to allow navigation to nav drawer
    */
    private void initNavBars()
    {
       if (toolbar != null)
       {
            getSupportActionBar().setDisplayHomeAsUpEnabled(true);
            toolbar.setNavigationIcon(R.drawable.ic_menu_white);
            toolbar.setNavigationOnClickListener(new View.OnClickListener()
            {
                @Override
                public void onClick(View v)
                {
                    navDrawer.openDrawer(GravityCompat.START);
                }
            });
       }
    }
}

//查询数据库中的用户类
ParseQuery=ParseQuery.getQuery（“学生类”）；
query.fromLocalDatastore（）.whereEqualTo（“student_id”，ParseUser.getCurrentUser（））；
//找到它，首先查看本地数据存储，然后转到数据库
getFirstInBackground（新的GetCallback（）
{
@凌驾
公共void完成（ParseObject ParseObject，parsee异常）
{
如果（e==null）
{
//检索到该对象
userClasses[PERIOD1]=parseObject.getString（“第一个周期”）；
userClasses[PERIOD2]=parseObject.getString（“第二个周期”）；
userClasses[PERIOD3]=parseObject.getString（“第三个周期”）；
userClasses[PERIOD4]=parseObject.getString（“第四个周期”）；
userClasses[PERIOD5]=parseObject.getString（“第五个周期”）；
userClasses[PERIOD6]=parseObject.getString（“第六个周期”）；
userClasses[PERIOD7]=parseObject.getString（“第七个周期”）；
//调试：显示方法返回所需的时间
Toast.makeText（getApplicationContext（），“在调用过程中=”+userClasses[PERIOD1]，Toast.LENGTH\u LONG.show（）；
}
其他的
{
//调试：显示是否发生异常
Toast.makeText（getApplicationContext（），“抛出异常”，Toast.LENGTH_SHORT.show（）；
}
}
});
//调试：显示代码达到此点所需的时间
Toast.makeText（getApplicationContext（），“after call=“+userClasses[PERIOD1]，Toast.LENGTH_LONG）.show（）；

屏幕一出现，toast“after call=”就会立即显示，并显示“after call=null”

祝酒词“during call=”大约3秒钟后出现，并说“during call=English”（这是它应该说的）

即使它不使用解析来保存它，我也不会介意。我总是可以使用parse来支持它，或者我只是做错了什么，还有更好的方法

如果你有兴趣，这里是我的全部主要活动

// query database for user's classes
ParseQuery<ParseObject> query = ParseQuery.getQuery("StudentClasses");
query.fromLocalDatastore().whereEqualTo("student_id", ParseUser.getCurrentUser());

// find it, first looking at local data store then going to database
query.getFirstInBackground(new GetCallback<ParseObject>()
{
    @Override
    public void done (ParseObject parseObject, ParseException e)
    {
        if (e == null)
        {
            // retrieved the object
            userClasses[PERIOD1] = parseObject.getString("first_period");
            userClasses[PERIOD2] = parseObject.getString("second_period");
            userClasses[PERIOD3] = parseObject.getString("third_period");
            userClasses[PERIOD4] = parseObject.getString("fourth_period");
            userClasses[PERIOD5] = parseObject.getString("fifth_period");
            userClasses[PERIOD6] = parseObject.getString("sixth_period");
            userClasses[PERIOD7] = parseObject.getString("seventh_period");

            // DEBUG: shows how long it takes for method to return
            Toast.makeText(getApplicationContext(),"during call = " + userClasses[PERIOD1], Toast.LENGTH_LONG).show();
        }
        else
        {
            // DEBUG: shows if exception happened
            Toast.makeText(getApplicationContext(),"Exception Thrown" ,Toast.LENGTH_SHORT).show();
        }
    }
});

// DEBUG: shows how long it takes for code to reach this point
Toast.makeText(getApplicationContext(),"after call = " + userClasses[PERIOD1], Toast.LENGTH_LONG).show();

    package maxbleggi.afstudentplanner;

import ... 

public class MainActivity extends AppCompatActivity
{
    // "MACROS" for user's class periods
    private final int PERIOD1 = 0;
    private final int PERIOD2 = 1;
    private final int PERIOD3 = 2;
    private final int PERIOD4 = 3;
    private final int PERIOD5 = 4;
    private final int PERIOD6 = 5;
    private final int PERIOD7 = 6;

    // toolbar
    private Toolbar toolbar;

    // navigation drawer
    private DrawerLayout navDrawer;

    // user's data
     public String[] userClasses = new String[10];

    // list to fill Classroom class with
    private List<ClassroomClass> classrooms;

    /*
    * on creation of activity
     */
    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        // initialise and set toolbar as actionbar
        toolbar = (Toolbar) findViewById(R.id.tool_bar);
        setSupportActionBar(toolbar);

        // initialize nav bars
        initNavBars();

        // initialize drawer layout
        NavigationView navView = (NavigationView) findViewById(R.id.navigation_view);

        // initialize nav drawer
        navDrawer = (DrawerLayout) findViewById(R.id.drawer);
        initNavDrawer(navDrawer);

        // initialize layout manager for recycler view
        RecyclerView.LayoutManager mainLayoutManager = new LinearLayoutManager(this);

        // initialize data for all classes before setting adapter
        initClassData();

        // set the adapter for recycler view
        RecyclerView.Adapter mainAdapter = new MainRecyclerAdapter(classrooms);

        // initialize recycler view elements
        RecyclerView mainRecyclerView = (RecyclerView) findViewById(R.id.main_recycler_view);

        // add layout manager to recycler view
        mainRecyclerView.setLayoutManager(mainLayoutManager);

        // add adapter to recycler view
        mainRecyclerView.setAdapter(mainAdapter);
    }

    /*
    * initializes the class data for each class
    */
    public void initClassData()
    {
        // check if a user is not cached
        ParseUser currentUser = ParseUser.getCurrentUser();
        if (currentUser == null)
        {
            // prompt user to Register screen
            // create intent to start activity
            Intent intent = new Intent(MainActivity.this, RegisterActivity.class);
            intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);

            // start new activity
            startActivity(intent);

            // stop current activity
            finish();
        }

        // query database for user's classes
        ParseQuery<ParseObject> query = ParseQuery.getQuery("StudentClasses");
        query.fromLocalDatastore().whereEqualTo("student_id", ParseUser.getCurrentUser());

        // find it, first looking at local data store then going to database
        query.getFirstInBackground(new GetCallback<ParseObject>()
        {
            @Override
            public void done (ParseObject parseObject, ParseException e)
            {
                if (e == null)
                {
                    // retrieved the object
                    userClasses[PERIOD1] = parseObject.getString("first_period");
                    userClasses[PERIOD2] = parseObject.getString("second_period");
                    userClasses[PERIOD3] = parseObject.getString("third_period");
                    userClasses[PERIOD4] = parseObject.getString("fourth_period");
                    userClasses[PERIOD5] = parseObject.getString("fifth_period");
                    userClasses[PERIOD6] = parseObject.getString("sixth_period");
                    userClasses[PERIOD7] = parseObject.getString("seventh_period");

                    // DEBUG: shows how long it takes for method to return
                    Toast.makeText(getApplicationContext(),"during call = " + userClasses[PERIOD1], Toast.LENGTH_LONG).show();
                }
                else
                {
                    // DEBUG: shows if exception happened
                    Toast.makeText(getApplicationContext(),"Exception Thrown" ,Toast.LENGTH_SHORT).show();
                }
            }
        });

        // DEBUG: shows how long it takes for code to reach this point
        Toast.makeText(getApplicationContext(),"after call = " + userClasses[PERIOD1], Toast.LENGTH_LONG).show();

        // fill all fields for class periods
        classrooms = new ArrayList<>();

        // titles of classes to add to list
        String[] classTitles = {"First Period", "Second Period", "Third Period", "Fourth Period",
                "Fifth Period", "Sixth Period", "Seventh Period"};

            // iterate over every period to add it to the list
            for (int i = 0; i <= PERIOD7; i++)
            {
                // if there was a class registered for that period
                if (userClasses[PERIOD3] != null)
                {
                    // add it to the class to be added to recycler view
                    classrooms.add(new ClassroomClass(userClasses[i], classTitles[i], i + 1));
                }
            }

    }

    /*
    * initialize navigation drawer
     */
    public void initNavDrawer(final DrawerLayout navDrawer)
    {
        final NavigationView navView = (NavigationView) findViewById(R.id.navigation_view);

        navView.setNavigationItemSelectedListener(new NavigationView.OnNavigationItemSelectedListener()
        {
            @Override
            public boolean onNavigationItemSelected(MenuItem menuItem)
            {
                menuItem.setChecked(true);
                navDrawer.closeDrawers();
                return true;
            }
        });
    }

    /*
    * initialize navigation bars to allow navigation to nav drawer
    */
    private void initNavBars()
    {
       if (toolbar != null)
       {
            getSupportActionBar().setDisplayHomeAsUpEnabled(true);
            toolbar.setNavigationIcon(R.drawable.ic_menu_white);
            toolbar.setNavigationOnClickListener(new View.OnClickListener()
            {
                @Override
                public void onClick(View v)
                {
                    navDrawer.openDrawer(GravityCompat.START);
                }
            });
       }
    }
}

package maxbleggi.afstudentplanner；
进口
公共类MainActivity扩展了AppCompatActivity
{
//用于用户的类周期的“宏”
私有最终整数周期1=0；
私人最终整数周期2=1；
私人最终整数周期3=2；
私人最终整数周期4=3；
私人最终整数周期5=4；
私人最终整数周期6=5；
私人最终整数周期7=6；
//工具栏
专用工具栏；
//导航抽屉
私人抽屉布局；
//用户数据
公共字符串[]用户类=新字符串[10]；
//课堂上要填写的列表
私人名单教室；
/*
*论活动的创造
*/
@凌驾
创建时受保护的void（Bundle savedInstanceState）
{
super.onCreate（savedInstanceState）；
setContentView（R.layout.activity_main）；
//初始化工具栏并将其设置为actionbar
工具栏=（工具栏）findViewById（R.id.tool\u栏）；
设置支持操作栏（工具栏）；
//初始化导航条
initNavBars（）；
//初始化抽屉布局
NavigationView navView=（NavigationView）findViewById（R.id.navigation\u视图）；
//初始化导航抽屉
navDrawer=（抽屉布局）findViewById（R.id.抽屉）；
初始化navDrawer（navDrawer）；
//初始化回收器视图的布局管理器
RecyclerView.LayoutManager mainLayoutManager=新的LinearLayoutManager（此）；
//在设置适配器之前初始化所有类的数据
initClassData（）；
//为回收器视图设置适配器
RecyclerView.Adapter mainAdapter=新的MainRecyclerAdapter（教室）；
//初始化回收器视图元素
RecyclerView mainRecyclerView=（RecyclerView）findViewById（R.id.main\u recycler\u视图）；
//将布局管理器添加到回收器视图
mainRecyclerView.setLayoutManager（mainLayoutManager）；
//将适配器添加到回收器视图
mainRecyclerView.setAdapter（mainAdapter）；
}
/*
*初始化每个类的类数据
*/
public void initClassData（）
{
//检查是否未缓存用户
ParseUser currentUser=ParseUser.getCurrentUser（）；
if（currentUser==null）
{
//提示用户注册屏幕
//创建启动活动的意图
意向意向=新意向（MainActivity.this、RegisterActivity.class）；
intent.addFlags（intent.FLAG\u ACTIVITY\u CLEAR\u TOP）；
//开始新的活动
星触觉（意向）；
//停止当前活动
完成（）；
}
//查询数据库中的用户类
解析查询=