如何修复 java.lang.IllegalStateException

Question

我目前正在进行我的 A Level Computer Science 控制评估，使用 Java 和 XML 在 Android Studio 中制作 Scout Manager 应用程序 - 我以前没有使用过这些。我现在正在开发一个 n 事件创建器。

我正在尝试创建一条记录，该记录将显示为哪个事件选择了哪个传输，但是我遇到了一个问题 - LogCat 给了我以下错误：

04-02 15:25:42.663 18482-18482/com.example.atomi.scoutmanagerprototype E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.atomi.scoutmanagerprototype, PID: 18482
    java.lang.IllegalStateException: Could not execute method for android:onClick
        at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:390)
        at android.view.View.performClick(View.java:4761)
        at android.view.View$PerformClick.run(View.java:19767)
        at android.os.Handler.handleCallback(Handler.java:739)
        at android.os.Handler.dispatchMessage(Handler.java:95)
        at android.os.Looper.loop(Looper.java:135)
        at android.app.ActivityThread.main(ActivityThread.java:5310)
        at java.lang.reflect.Method.invoke(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:372)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:901)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:696)
     Caused by: java.lang.reflect.InvocationTargetException
        at java.lang.reflect.Method.invoke(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:372)
        at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:385)
        at android.view.View.performClick(View.java:4761) 
        at android.view.View$PerformClick.run(View.java:19767) 
        at android.os.Handler.handleCallback(Handler.java:739) 
        at android.os.Handler.dispatchMessage(Handler.java:95) 
        at android.os.Looper.loop(Looper.java:135) 
        at android.app.ActivityThread.main(ActivityThread.java:5310) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at java.lang.reflect.Method.invoke(Method.java:372) 
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:901) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:696) 
     Caused by: java.lang.IllegalStateException: attempt to re-open an already-closed object: SQLiteDatabase: /data/data/com.example.atomi.scoutmanagerprototype/databases/ScoutManager.db
        at android.database.sqlite.SQLiteClosable.acquireReference(SQLiteClosable.java:55)
        at android.database.sqlite.SQLiteDatabase.queryWithFactory(SQLiteDatabase.java:1158)
        at android.database.sqlite.SQLiteDatabase.query(SQLiteDatabase.java:1034)
        at android.database.sqlite.SQLiteDatabase.query(SQLiteDatabase.java:1202)
        at com.example.samogonovsky.scoutmanager.databaseHandler.getRandomTransport(databaseHandler.java:649)
        at com.example.samogonovsky.scoutmanager.frmCreateEvent2.saveAndExit(frmCreateEvent2.java:528)

但是，我没有在这两个地方关闭光标。

这是“databaseHandler”类中的代码：

//Select a random mode of transport
    public Cursor getRandomTransport()
    {
        Cursor cursor=db.query(TABLE_TRANSPORT, null, null, null, null, null, "RANDOM()limit 1");
        if (cursor!=null&&cursor.moveToFirst())
        {
            cursor.moveToFirst();
        }
        else
        {
            cursor=null;
        }
        return cursor;
    }

这是“frmAddEvent2”类中的代码：

double TotalTransportCost;
        if (providingtransport==true)
        {
            int peopletotransport=noOfPeople;
            TotalTransportCost = 0;
            do
            {

                int eventtransportid=createEventTransportId();

                Cursor ModeOfTransport = DatabaseHandler.getRandomTransport();

                if (ModeOfTransport.moveToFirst()) {

                    int transportid=ModeOfTransport.getInt(ModeOfTransport.getColumnIndex(
                            DatabaseHandler.COLUMN_TRID));

                    double PriceForHiring = ModeOfTransport.getDouble(ModeOfTransport.getColumnIndex(
                            DatabaseHandler.COLUMN_HCOST));

                    double PricePerMile = ModeOfTransport.getDouble(ModeOfTransport.getColumnIndex(
                            DatabaseHandler.COLUMN_MCOST));

                    int NoOfSeats = ModeOfTransport.getInt(ModeOfTransport.getColumnIndex(
                            DatabaseHandler.COLUMN_SEATNO));

                    double ModeCost = ((PricePerMile*distancefrombase)+PriceForHiring);

                    eventTransportDetails eventtransport = new eventTransportDetails(eventtransportid,
                            id, transportid);

                    DatabaseHandler.createEventTransport(eventtransport);

                    BigDecimal bigdecimalmodecost=new BigDecimal(ModeCost);
                    BigDecimal bigdecimalpropermodecost=((bigdecimalmodecost.setScale(2,bigdecimalmodecost.ROUND_DOWN)));
                    double propermodecost=bigdecimalpropermodecost.doubleValue();
                    TotalTransportCost = TotalTransportCost + propermodecost;
                    peopletotransport = (peopletotransport-NoOfSeats);
                    ModeOfTransport.close();
                }
                else
                {
                    Toast.makeText(
                            context,
                            "Error - you have not added any lunches, therefore food " +
                                    "cannot be added.",
                            Toast.LENGTH_SHORT
                    ).show();
                    return;
                }
            }
            while (peopletotransport>0);
        }
        else
        {
            TotalTransportCost=0;
        }

我想知道是否有人能指出我正确的方向？

此外，请随时对我的问题提出任何改进建议 - 如上所述，其中很多内容对我来说都是新的，所以我可能遗漏了一些非常重要的材料。

Answer 1

好的，事实证明，我输入了“db.close();”在 databaseHandler 中的一些函数之后——通过删除所有这些函数，我解决了这个问题。如果您认为这个问题最好不要出现在网站上，请告诉我，我会删除它。感谢所有评论的人。