Question

我是Android新手，现在在从SQLite到editText检索数据时遇到问题。当按下该行时，应用程序崩溃了。有谁知道如何解决这一问题？是不是因为cursor未初始化或因为sql问题？希望有人能帮助我找出问题。谢谢。

  c = database.rawQuery("SELECT  i.Name, i.Date, i.Status, i.Weather, w.Subcontractors, w.NumberOfPerson, w.NumberOfHours FROM Information i LEFT JOIN WorkForce w ON w.TInfo_id = i.ID" +
                         " LEFT JOIN WorkDetails wd ON wd.Twf_id = w.ID WHERE i.Name = ? AND i.Date= ? ",

UpdatePage.java

package com.example.project.project;

import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.widget.EditText;
import android.widget.Spinner;
import android.widget.Toast;

import com.example.project.project.API.InfoAPI;
import com.example.project.project.TimeSheet.Details;
import com.example.project.project.TimeSheet.Force;
import com.example.project.project.TimeSheet.Info;
import com.example.project.project.database.MyDatabaseHelper;


public class UpdatePage extends AppCompatActivity {
    InfoAPI sqlcon;
    private SQLiteDatabase database;
    private MyDatabaseHelper dbHelper;
    private Cursor c;


    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        dbHelper = new MyDatabaseHelper(this);
        setContentView(R.layout.updatepage);
        final String name1 = getIntent().getExtras().getString("name");
        final String date = getIntent().getExtras().getString("date");
        RetrievePage(name1, date);
    }


    public void RetrievePage(String name, String date) {
        final String name2 = name;
        final String date2 = date;
        database = dbHelper.getWritableDatabase();
         c = database.rawQuery("SELECT  i.Name, i.Date, i.Status, i.Weather, w.Subcontractors, w.NumberOfPerson, w.NumberOfHours FROM Information i LEFT JOIN WorkForce w ON w.TInfo_id = i.ID LEFT JOIN WorkDetails wd ON wd.Twf_id = w.ID WHERE i.Name = ? AND i.Date= ? ",
                 new String[]{String.valueOf(name2),String.valueOf(date2)}, null);
        final EditText name3 = (EditText) findViewById(R.id.editText9);
        final EditText date3 = (EditText) findViewById(R.id.editText12);
        name3.setText(name2);
        date3.setText(date2);
        final Spinner weather3 = (Spinner) findViewById(R.id.spinner5);
        final Spinner status3 = (Spinner) findViewById(R.id.spinner7);
        final EditText subC3 = (EditText) findViewById(R.id.editText17);
        final EditText noP = (EditText) findViewById(R.id.editText18);
        final EditText noH = (EditText) findViewById(R.id.editText19);
        final Spinner poject3 = (Spinner) findViewById(R.id.spinner8);
        if (c != null) {
            c.moveToFirst();
            while (c.moveToNext()) {
                Info I = new Info();
                Force WF = new Force();
                Details WD = new Details();

                String Weather = c.getString(c.getColumnIndex(MyDatabaseHelper.Weather));
                String Status = c.getString(c.getColumnIndex(MyDatabaseHelper.Status));
                String SubC = c.getString(c.getColumnIndex(MyDatabaseHelper.Subcontractors));
                String NoP = c.getString(c.getColumnIndex(MyDatabaseHelper.NumberOfPerson));
                String NoH = c.getString(c.getColumnIndex(MyDatabaseHelper.NumberOfHours));
                String Project = c.getString(c.getColumnIndex(MyDatabaseHelper.Project));


                //I.setWeather(Weather);
               // I.setStatus(Status);
                WF.setSubcontractors(SubC);
                WF.setNoOfPerson(NoP);
                WF.setNoOfHours(NoH);
                //WD.setProject(Project);


                subC3.setText(SubC);
                noP.setText(NoP);
                noH.setText(NoH);

            }

        }

    }
    }

错误LogCat

 ComponentInfo{com.example.project.project/com.example.project.project.UpdatePage}: java.lang.IllegalStateException: Couldn't read row 1, col -1 from CursorWindow.  Make sure the Cursor is initialized correctly before accessing data from it.
                at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2416)
                at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
                at android.app.ActivityThread.-wrap11(ActivityThread.java)
                at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
                at android.os.Handler.dispatchMessage(Handler.java:102)
                at android.os.Looper.loop(Looper.java:148)
                at android.app.ActivityThread.main(ActivityThread.java:5417)
                at java.lang.reflect.Method.invoke(Native Method)
                at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
                at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
         Caused by: java.lang.IllegalStateException: Couldn't read row 1, col -1 from CursorWindow.  Make sure the Cursor is initialized correctly before accessing data from it.
                at android.database.CursorWindow.nativeGetString(Native Method)
                at android.database.CursorWindow.getString(CursorWindow.java:438)

Answer 1

moveToFirst()移至第一行。 moveToNext()然后移到第二行。

但你的问题是缺少专栏。当您不知道列是否存在时，将使用getColumnIndex()。要获取您认为存在的列的索引，请使用getColumnIndexOrThrow()，以便您在错误消息中立即看到您在查询中忘记了哪一列。

无法从CursorWindow读取第1行col -1。在从中访问数据之前，请确保Cursor已正确初始化

1 个答案: