Android SQLite Column Sum

Question

我无法获取SQLite列的总和。该应用程序不断崩溃。任何帮助将不胜感激，谢谢=)。这是我在数据库助手和主要活动中的代码：

public class DatabaseOperator {
private DataManager dataManager;
...
public int getTotalExpenses()
{
SQLiteDatabase database = dataManager.getReadableDatabase();
Cursor cursor = database.rawQuery("SELECT SUM(" + Integer.valueOf(Expenses.C_TOTAL_PRICE) + ") FROM " + Expenses.TABLE, null);
cursor.moveToFirst();
int i = cursor.getInt(0);
cursor.close();
return i;
}
//MainActivity.class
TextView textTotalExpenses;
int totalExpenses;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
DatabaseOperator databaseOperator = new DatabaseOperator(this);
textTotalExpenses = (TextView) findViewById(R.id.textTotalExpenses);
totalExpenses = databaseOperator.getTotalExpenses();
textTotalExpenses.setText(totalExpenses);

03-26 09：31：23.483 5818-5818/com.example.everydaybudgeting20 E/Android运行时：致命 异常：主要 流程： com.example.everydaybudgeting20， PID： 5818 java.lang.RuntimeException： 无法启动活动 ComponentInfo{com.example.everydaybudgeting20/com.example.everydaybudgeting20.MainActivity}： java.lang.NumberFormatException： 对于输入字符串："totalPrice" at android.app.ActivityThread.performLaunchActivity(ActivityThread.java：2665) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java：2726) at android.app.ActivityThread.-wrap12(ActivityThread.java) at android.app.ActivityThread$H.handleMessage(ActivityThread.java：1477) at android.os.Handler.dispatchMessage(Handler.java：102) at android.os.Looper.loop(Looper.java：154) at android.app.ActivityThread.main(ActivityThread.java：6119) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java：886) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java：776) 由以下原因引起：java.lang.NumberFormatException：对于输入字符串："totalPrice" at java.lang.Integer.parseInt(Integer.java：521) at java.lang.Integer.valueOf(Integer.java：611) at com.example.everydaybudgeting20.DatabaseOperator.getTotalExpenses(DatabaseOperator.java：229) at com.example.everydaybudgeting20.MainActivity.onCreate(MainActivity.java：76) at android.app.Activity.performCreate(Activity.java：6679) at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java：1118) at android.app.ActivityThread.performLaunchActivity(ActivityThread.java：2618) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java：2726) at android.app.ActivityThread.-wrap12(ActivityThread.java) at android.app.ActivityThread$H.handleMessage(ActivityThread.java：1477) at android.os.Handler.dispatchMessage(Handler.java：102) at android.os.Looper.loop(Looper.java：154) at android.app.ActivityThread.main(ActivityThread.java：6119) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java：886) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java：776)

Answer 1

只是自己修复了它。感谢您的帮助！

public int getTotalExpenses()
{
int total = 0;
SQLiteDatabase database = dataManager.getReadableDatabase();
Cursor cursor = database.rawQuery("SELECT SUM("+ Expenses.C_TOTAL_PRICE + ") FROM " + Expenses.TABLE, null);
if (cursor.moveToFirst())
{
total = cursor.getInt(0);
}
while (cursor.moveToNext());
return total;
}