SQLite数据库查询和AsyncTask

嗨Anddroid专家！SQLite数据库查询和AsyncTask

我目前正在编写一个具有SQLite数据库和MPcharts的应用程序。这个想法是我创建了一个包含少量数据库表的SQLite数据库，并将数据从数据库中提取出来并创建MP图表。我在不同的应用程序中使用了类似的方法，它工作正常。在这种情况下，查询稍微复杂一些，应用程序停止，图表上没有数据显示。在网上调查后，我觉得AsyncTask会帮助我解决这个问题。我不知道如何将AsyncTask应用于我的案例。基本上，将Arraylist xDataMonthCategory（）和Arraylist yDataPieChartCategoryMonth（）链接到Piechart，并使用AsyncTask在后台运行SQLite查询。我测试了我的查询，我知道数据在那里。请帮帮我。非常感谢！！！

这里是MP饼图的Java类：

 import android.graphics.Color; 
    import android.os.Bundle; 
    import android.support.design.widget.FloatingActionButton; 
    import android.support.design.widget.Snackbar; 
    import android.support.v7.app.AppCompatActivity; 
    import android.support.v7.widget.Toolbar; 
    import android.view.View; 

    import com.github.mikephil.charting.charts.PieChart; 
    import com.github.mikephil.charting.components.Legend; 
    import com.github.mikephil.charting.data.Entry; 
    import com.github.mikephil.charting.data.PieData; 
    import com.github.mikephil.charting.data.PieDataSet; 
    import com.github.mikephil.charting.formatter.PercentFormatter; 

    import java.util.ArrayList; 

public class MTDPieCharts extends AppCompatActivity { 

@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_mtdpie_charts); 
    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar); 
    setSupportActionBar(toolbar); 

    FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab); 
    fab.setOnClickListener(new View.OnClickListener() { 
     @Override 
     public void onClick(View view) { 
      Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG) 
        .setAction("Action", null).show(); 
     } 
    }); 
    MTDPieChartCategory(); 
    //MTDPieChartItems(); 
} 

//MTD Category PieChart 
public void MTDPieChartCategory() { 

    DataBaseHelper databasehelper = new DataBaseHelper(MTDPieCharts.this); 
    PieChart MTDcategoryChart = new PieChart(this); 
    MTDcategoryChart = (PieChart) findViewById(R.id.MTDPieChartCategory); 
    //get yVals and datasets of MTD Category chart 
    ArrayList<Entry> yValsCategoryAMT = new ArrayList<Entry>(); 
    for(int i = 0; i < databasehelper.yDataPieChartCategoryMonth().size(); i++) 
     yValsCategoryAMT.add(new Entry(databasehelper.yDataPieChartCategoryMonth().get(i), i)); 

    //get xVals of MTD Category chart 
    ArrayList<String> xValsCategory = new ArrayList<String>(); 
    for(int i = 0; i < databasehelper.xDataMonthCategory().size(); i++) 
     xValsCategory.add(databasehelper.xDataMonthCategory().get(i)); 

    PieDataSet MTDCategorySet = new PieDataSet(yValsCategoryAMT, ""); 

    //set yvals attribute 
    MTDCategorySet.setSliceSpace(3); 
    MTDCategorySet.setSelectionShift(5); 

    //add many colors 
    MTDCategorySet.setColors(new int[]{R.color.BlueA100, R.color.Cyan500, R.color.colorAccent, R.color.DeepPurpleA200, R.color.BlueA100, R.color.Teal200, R.color.Pink200, R.color.Pink500, R.color.purple},this); 

    // configue pie chart 
    MTDcategoryChart.setUsePercentValues(true); 
    MTDcategoryChart.setRotationEnabled(true); 
    MTDcategoryChart.setRotationAngle(0); 
    MTDcategoryChart.setDescriptionPosition(350, 550); 
    MTDcategoryChart.setDrawHoleEnabled(true); 
    MTDcategoryChart.setHoleColor(Color.TRANSPARENT); 
    MTDcategoryChart.setHoleRadius(13); 
    MTDcategoryChart.setTransparentCircleRadius(18); 
    MTDcategoryChart.getLegend().setPosition(Legend.LegendPosition.RIGHT_OF_CHART); 
    //MTDcategoryChart.getLegend().setXEntrySpace(3); 
    // MTDcategoryChart.getLegend().setYEntrySpace(3); 
    MTDcategoryChart.getLegend().setTextColor(Color.BLUE); 
    MTDcategoryChart.setDescription("Category"); 
    MTDcategoryChart.setDescriptionTextSize(13); 
    MTDcategoryChart.setDescriptionColor(Color.BLUE); 

    //get category chart data 
    PieData MTDCategoryPieData = new PieData(xValsCategory, MTDCategorySet); 
    MTDCategoryPieData.setValueFormatter(new PercentFormatter()); 
    MTDCategoryPieData.setValueTextSize(11); 
    MTDCategoryPieData.setValueTextColor(Color.BLUE); 
    MTDcategoryChart.setData(MTDCategoryPieData); 


    //refresh data 
    MTDcategoryChart.invalidate(); 

}

数据库辅助类：

import android.content.ContentValues; 
    import android.content.Context; 
    import android.database.Cursor; 
    import android.database.SQLException; 
    import android.database.sqlite.SQLiteDatabase; 
    import android.database.sqlite.SQLiteOpenHelper; 
    import android.util.Log; 

    import java.text.SimpleDateFormat; 
    import java.util.ArrayList; 
    import java.util.Date; 

     //create category table 
public static final String Create_Table_Category="create table if not exists "+ 
     TableData.TableInfo.DataBase_Table_Category+ "(" + 
     TableData.TableInfo.COL_C1_CategoryID+" integer primary key autoincrement,"+ 
     TableData.TableInfo.COL_C2_Description+" text not null);"; 

     //create table spending 
     public static final String Create_Table_Spending="create table if not exists "+ 
     TableData.TableInfo.DataBase_Table_Spending+" ("+TableData.TableInfo.COL_S1_SpendingID+" integer primary key autoincrement,"+ 
     TableData.TableInfo.COL_S2_Spending_DT+" Datetime not null,"+ 
     TableData.TableInfo.COL_S3_ItemID+" integer not null,"+ 
     TableData.TableInfo.COL_S4_AMT+" Float not null," + 
     "FOREIGN key ("+TableData.TableInfo.COL_S3_ItemID+") REFERENCES " +TableData.TableInfo.DataBase_Table_Items+" ("+TableData.TableInfo.COL_I1_ItemID+") ON DELETE CASCADE);"; 

// create table Item 

public static final String Create_Table_Items="Create table if not exists " + 
     TableData.TableInfo.DataBase_Table_Items+" ("+ 
     TableData.TableInfo.COL_I1_ItemID+" integer primary key autoincrement,"+ 
     TableData.TableInfo.COL_I2_Description+" Text not null,"+ 
     TableData.TableInfo.COL_I3_CategoryID+" integer not null,"+ 

     "FOREIGN key ("+TableData.TableInfo.COL_I3_CategoryID+") REFERENCES " +TableData.TableInfo.DataBase_Table_Category+ " ("+TableData.TableInfo.COL_C1_CategoryID+") ON DELETE CASCADE);"; 
    // create table Users 
public static final String Created_Table_Users="create table if not exists "+ 
     TableData.TableInfo.DataBase_Table_Users+ " ("+ TableData.TableInfo.COL_U1_UserID+" integer primary key autoincrement ,"+ 
     TableData.TableInfo.COL_U2_UserName+" text not null ,"+ TableData.TableInfo.COL_U3_Password+" Text not null, "+ 
     TableData.TableInfo.COL_U4_Created_DT+" Datetime not null);"; 

public static final String Drop_table_Category="drop table if exists "+TableData.TableInfo.DataBase_Table_Category; 
public static final String Drop_table_Items="drop table if exists "+TableData.TableInfo.DataBase_Table_Items; 
public static final String Drop_table_Spending="drop table if exists "+TableData.TableInfo.DataBase_Table_Spending; 
public static final String Drop_table_Users="drop table if exists "+ TableData.TableInfo.DataBase_Table_Users; 

SQLiteDatabase db; 
// declare variables 
public static final String YearEndPieChartMonth="YearEndPieChartMonth"; 
public static final YearEndPieChartMonthValues= String     "YearEndPieChartMonthValues"; 
public static final String MonthPieChartCategory="MonthPieChartCategory"; 
public static final String MonthPieCHartCategoryValues="MonthPieCHartCategoryValues"; 
public static final String MonthPieChartItems="MonthPieChartItems"; 
public static final String MonthPiechartItemsValues="MonthPiechartItemsValues"; 
public static final String YearEndPieChartCategory="YearEndPieChartCategory"; 
public static final String YearEndCategoryValues="YearEndCategoryValues"; 
public static final String YearEndPieChartItems="YearEndPieChartItems"; 
public static final String YearEndItemsValues="YearEndItemsValues"; 

public DataBaseHelper(Context context) { 
    super(context, TableData.TableInfo.DataBase_Name, null, TableData.TableInfo.DataBase_version); 
} 



@Override 
public void onCreate(SQLiteDatabase db) { 
    //create Category table 
    db.execSQL(Create_Table_Category); 
    Log.d("Database operation:", "Category table created"); 
    //insert data into Category table 
    String sql_category="INSERT INTO " +  TableData.TableInfo.DataBase_Table_Category+" ("+  TableData.TableInfo.COL_C2_Description+") 
    VALUES('Housing'),('Utilities'),('Household'),('Groceries'),('Living'),('Transportation'),('HealthCare'),('Personal'),('EatingOut'),('Entertainments'),('Children'),('DebtPayments'),('Savings')"; 
    db.execSQL(sql_category); 
    Log.d("Category table:","Data inserted"); 

    //create Items table 
    db.execSQL(Create_Table_Items); 
    Log.d("Datbase operation:", "Item table created "); 
    // insert data into Item table 
    String sql_Items="insert into "+ TableData.TableInfo.DataBase_Table_Items+ " ("+ TableData.TableInfo.COL_I2_Description+" ,"+ TableData.TableInfo.COL_I3_CategoryID+") values('Rent',1),('Mortgage',1),('StrataFees',1),('PropertyTaxes',1),('HouseInsurance',1),('Phone',2),('Cell',2),('CableTVInternet',2),('GAS',2),('Hybro',2), ('Security',2),('Electricity',2),('Water',2),('StorageLocker',3),('Decor',3),('Gardening',3),('Garbage',3),('MiscItems',3),('Food',4),('BabyNeeds',4),('Cleaning',4),('Toiletries',4),('Kitchenwares',4),('PersonalCare',5),('BankFees',5), ('DryCleaning',5),('PetCosts',5),('Fuel',6),('AutoInsurance',6),('Transit',6),('Parking',6),('Taxi',6),('MedicalPremiums',7),('LifeInsurance',7),('Medication',7),('EyeCare',7),('Dental',7),('WellnessCosts',7),('Tobacco',8),('Alcohol',8),('BooksCDs',8),('Donations',8),('Subscriptions',8),('Meals',9),('Snacks',9),('TakeOut',9),('CoffeeWater',9),('SportsEquipmentFees',10),('Movies',10),('Hobbies',10),('Gaming',10),('FitnessMemberships',10),('DayCare',11),('LessonsActivities',11),('Allowance',11),('SchoolSuppliesFees',11),('Babysitting',11),('Loans',12),('CreditCards',12),('Leases',12),('SupportPayments',12),('GovernmentDebts',12),('EmergencyFund',13),('RRSP',13),('RESPs',13),('TravelVacations',13),('CarRepairs',13),('CLothing',13), ('Gifts',13),('AssistingFamilyFriends',13)"; 
    db.execSQL(sql_Items); 
    Log.d("Items","Data inserted"); 
    //create spending table 
    db.execSQL(Create_Table_Spending); 
    Log.d("Database operation:", "Spending table created "); 
    db.execSQL(Created_Table_Users); 
} 

@Override 
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { 
    db.execSQL(Drop_table_Category); 
    db.execSQL(Drop_table_Items); 
    db.execSQL(Drop_table_Spending); 
    db.execSQL(Drop_table_Users); 
    onCreate(db); 

} 
public DataBaseHelper open() throws SQLException { 
    db = this.getWritableDatabase(); 
    return this; 
} 

public void close() { 
    db.close(); 
} 

public SQLiteDatabase getDatabaseInstance() { 
    return db; 
} 

public String getTime(){ 
    SimpleDateFormat dateFormat=new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); 
    Date date=new Date(); 

    return dateFormat.format(date); 
} 


//current month pie chart category 
public ArrayList<String> xDataMonthCategory(){ 
    ArrayList<String> xnewDataCategory=new ArrayList<String>(); 
    SQLiteDatabase db=this.getReadableDatabase(); 
    String sql="select distinct c."+ TableData.TableInfo.COL_C2_Description+" as MonthPieChartCategory from " + TableData.TableInfo.DataBase_Table_Spending+" s join "+ TableData.TableInfo.DataBase_Table_Items+" i on i."+ TableData.TableInfo.COL_I1_ItemID+"=s."+ TableData.TableInfo.COL_S3_ItemID+" join "+ TableData.TableInfo.DataBase_Table_Category+" c on c."+ TableData.TableInfo.COL_C1_CategoryID+"=i."+ TableData.TableInfo.COL_I3_CategoryID+" where strftime('%Y',"+ TableData.TableInfo.COL_S2_Spending_DT+")=strftime('%Y',date('now')) and strftime('%m',"+ TableData.TableInfo.COL_S2_Spending_DT+")=strftime('%m',date('now')) group by c."+ TableData.TableInfo.COL_C2_Description+" order by c."+ TableData.TableInfo.COL_C2_Description+" desc"; 
    Cursor cursor=db.rawQuery(sql,null); 
    for(cursor.moveToFirst();!cursor.isAfterLast();cursor.moveToLast()) { 
     xnewDataCategory.add(cursor.getString(cursor.getColumnIndex(MonthPieChartCategory))); 
    } 
    cursor.close(); 
    return xnewDataCategory; 

} 
//current month pie chart category y values 
public ArrayList<Float> yDataPieChartCategoryMonth(){ 
    ArrayList<Float> ynewDataPieCHartCategoryMonth=new ArrayList<Float>(); 
    SQLiteDatabase db=this.getReadableDatabase(); 
    String sql="select sum("+ TableData.TableInfo.COL_S4_AMT+") MonthPieCHartCategoryValues,c."+ TableData.TableInfo.COL_C2_Description+" Category from "+ TableData.TableInfo.DataBase_Table_Spending+" s join "+ TableData.TableInfo.DataBase_Table_Items+" i on i."+ TableData.TableInfo.COL_I1_ItemID+"=s."+ TableData.TableInfo.COL_S3_ItemID+ " join "+ TableData.TableInfo.DataBase_Table_Category+" c on c."+ TableData.TableInfo.COL_C1_CategoryID+"=i."+ TableData.TableInfo.COL_I3_CategoryID + " where strftime('%Y',"+ TableData.TableInfo.COL_S2_Spending_DT+")=strftime('%Y',Date('now')) and strftime('%m',"+ TableData.TableInfo.COL_S2_Spending_DT+")=strftime('%m',date('now')) group by c."+ TableData.TableInfo.COL_C2_Description+" order by Category desc"; 
    Cursor cursor=db.rawQuery(sql,null); 
    for(cursor.moveToFirst();!cursor.isAfterLast();cursor.moveToLast()){ 
     ynewDataPieCHartCategoryMonth.add(cursor.getFloat(cursor.getColumnIndex(MonthPieCHartCategoryValues))); 
    } 
    cursor.close(); 
    return ynewDataPieCHartCategoryMonth; 

}

来源

2016-11-08 J Huang

你必须使用游标装载机&内容提供商。

https://developer.android.com/training/load-data-background/index.html

来源

2016-11-08 20:40:15

嘛，你不*有*使用光标装载机和内容提供商，但是这不是去一个可怕的方式。您*必须在后台线程上执行数据库访问，而不是在UI线程上执行。有很多方法可以做到这一点。 – GreyBeardedGeek

你能给我一个提示吗？我正在努力......但还没有能力。我是新来的。 –

我能够做到这一点，不知道下一步该去哪里。 –

SQLite数据库查询和AsyncTask

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