Question

我正在创建一个使用SQLiteDatabase存储ListView项的应用。但是，在从数据库填充ListView中的数据时，我收到错误，并且应用程序崩溃。

这是我的数据库 -

import java.util.ArrayList;

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;

public class NotesDatabase extends SQLiteOpenHelper {

private static final String NOTE_NAME = "name";
private static final String NOTE_ID = "id";
private static final String NOTE_SUBJECT = "subject";

private static final String DATABASE_NAME = "notesDatabase";
private static final String TABLE_NOTES = "notes";
private static final int DATABASE_VERSION = 1;
private static final String CREATE_NOTES_TABLE = "CREATE TABLE " + TABLE_NOTES + "("
        + NOTE_ID + " INTEGER PRIMARY KEY," + NOTE_NAME + " TEXT,"
        + NOTE_SUBJECT + " TEXT" + ")";
public NotesDatabase(Context context) {
    super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {

    try {
        db.execSQL(CREATE_NOTES_TABLE);
    }
    catch(SQLException e) {
        e.printStackTrace();
    }
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

    db.execSQL("DROP TABLE IF EXSISTS topics");
    onCreate(db);
}
public void addNote(Note note) {
    SQLiteDatabase db = this.getWritableDatabase();

    ContentValues notes = new ContentValues();
    notes.put(NOTE_NAME, note.getNote());
    notes.put(NOTE_SUBJECT, note.getSubject());

    db.insert(TABLE_NOTES, null, notes);
    db.close();
}
public void removeNote(Note note) {

    SQLiteDatabase db = this.getWritableDatabase();

    db.delete(TABLE_NOTES, NOTE_NAME + " = ?", 
            new String[] {note.getNote()});

    db.close();
}
public ArrayList<Note> getNotes(){

    ArrayList<Note> notes = new ArrayList<Note>();

    String selectQuery = "SELECT * FROM " + TABLE_NOTES;

    SQLiteDatabase db = this.getWritableDatabase();
    Cursor cur = db.rawQuery(selectQuery, null);

    if(cur.moveToFirst()) {
        do {
            Note note = new Note();
            note.setId(Integer.parseInt(cur.getString(0)));
            note.setNote(cur.getString(cur.getColumnIndex(NOTE_NAME)));
            note.setSubject(cur.getString(cur.getColumnIndex(NOTE_SUBJECT)));
            notes.add(note);
        } while(cur.moveToNext());
    }
    db.close();
    return notes;
}
public void updateNote(String old_name, String new_name) {
    SQLiteDatabase db = this.getWritableDatabase();

    ContentValues topic = new ContentValues();

    topic.put(NOTE_NAME, new_name);

    db.update(TABLE_NOTES, topic, NOTE_NAME + " = ?", 
            new String[] {old_name});
    db.close();
}
}

Note.java -

public class Note {

String _Note;
int _id;
String subject;

public String getSubject() {
    return subject;
}
public void setSubject(String subject) {
    this.subject = subject;
}
public Note() {

}
public Note(int id, String Note, String Subject) {
    this._id = id;
    this._Note = Note;
    this.subject = Subject;
}
public Note(String Note, String Subject) {
    this._Note = Note;
    this.subject = Subject;
}
public Note(String Note) {
    this._Note = Note;
}
public String getNote() {
    return _Note;
}
public void setNote(String _Note) {
    this._Note = _Note;
}
public int getId() {
    return _id;
}
public void setId(int _id) {
    this._id = _id;
}

}

NotesDatabase.java -

import java.util.ArrayList;

import android.os.Bundle;

import android.app.Activity;

import android.content.Intent;

import android.util.Log;

import android.view.Menu;
import android.view.View;

import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;

public class Notes_page extends Activity {

ArrayList<Note> notes = new ArrayList<Note>();

NotesDatabase ndb = new NotesDatabase(this);
private NoteAdapter adapter;

private ListView notes_list;
private TextView subject_display;

String subject;

int requestCode = 1;

@Override
public void onCreate(Bundle savedInstanceState) {

    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_notes_page);

    notes_list = (ListView) findViewById(R.id.notes);
    ndb.getWritableDatabase();
    notes = ndb.getNotes();
    adapter = new NoteAdapter(this, notes);

    subject = getIntent().getStringExtra("SUBJECT_NAME");

    notes_list.setAdapter(adapter);

    subject_display = (TextView) findViewById(R.id.subject_name);
    subject_display.setText(subject);
}

public void onClickAddNewNote(View v) {
    startActivityForResult(new Intent("com.Swap.Add_New_Note"), requestCode);

}

public void onActivityResult(int request_Code, int result_Code, Intent i) {
    if(request_Code == requestCode) {
        if(result_Code == RESULT_OK) {
            Note mNote = new Note(i.getStringExtra("NOTE"), getIntent().getStringExtra("SUBJECT_NAME"));
            ndb.getWritableDatabase();
            ndb.addNote(mNote);
            Log.d("AddNote", "Note Succesfully Added to Database");
            adapter.add(mNote);
            adapter.notifyDataSetChanged();

            Toast.makeText(getBaseContext(), mNote.getNote(), Toast.LENGTH_SHORT).show();
        }
    }
} 

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    getMenuInflater().inflate(R.menu.activity_notes_page, menu);
    return true;
}
}

这是LogCat错误日志 -

04-13 22:17:10.766: E/linker(25692): load_library(linker.cpp:759): library "libmaliinstr.so" not found
04-13 22:17:14.816: E/CursorWindow(25692): Failed to read row 0, column -1 from a CursorWindow which has 1 rows, 2 columns.
04-13 22:17:14.869: E/AndroidRuntime(25692): FATAL EXCEPTION: main
04-13 22:17:14.869: E/AndroidRuntime(25692): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.Swap.RR/com.Swap.RR.Notes_page}: java.lang.IllegalStateException: Couldn't read row 0, col -1 from CursorWindow.  Make sure the Cursor is initialized correctly before accessing data from it.
04-13 22:17:14.869: E/AndroidRuntime(25692):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2364)
04-13 22:17:14.869: E/AndroidRuntime(25692):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2416)
04-13 22:17:14.869: E/AndroidRuntime(25692):    at android.app.ActivityThread.access$600(ActivityThread.java:174)
04-13 22:17:14.869: E/AndroidRuntime(25692):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1382)
04-13 22:17:14.869: E/AndroidRuntime(25692):    at android.os.Handler.dispatchMessage(Handler.java:107)
04-13 22:17:14.869: E/AndroidRuntime(25692):    at android.os.Looper.loop(Looper.java:194)
04-13 22:17:14.869: E/AndroidRuntime(25692):    at android.app.ActivityThread.main(ActivityThread.java:5409)
04-13 22:17:14.869: E/AndroidRuntime(25692):    at java.lang.reflect.Method.invokeNative(Native Method)
04-13 22:17:14.869: E/AndroidRuntime(25692):    at java.lang.reflect.Method.invoke(Method.java:525)
04-13 22:17:14.869: E/AndroidRuntime(25692):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
04-13 22:17:14.869: E/AndroidRuntime(25692):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:606)
04-13 22:17:14.869: E/AndroidRuntime(25692):    at dalvik.system.NativeStart.main(Native Method)
04-13 22:17:14.869: E/AndroidRuntime(25692): Caused by: java.lang.IllegalStateException: Couldn't read row 0, col -1 from CursorWindow.  Make sure the Cursor is initialized correctly before accessing data from it.
04-13 22:17:14.869: E/AndroidRuntime(25692):    at android.database.CursorWindow.nativeGetString(Native Method)
04-13 22:17:14.869: E/AndroidRuntime(25692):    at android.database.CursorWindow.getString(CursorWindow.java:434)
04-13 22:17:14.869: E/AndroidRuntime(25692):    at android.database.AbstractWindowedCursor.getString(AbstractWindowedCursor.java:51)
04-13 22:17:14.869: E/AndroidRuntime(25692):    at com.Swap.RR.NotesDatabase.getNotes(NotesDatabase.java:78)
04-13 22:17:14.869: E/AndroidRuntime(25692):    at com.Swap.RR.Notes_page.onCreate(Notes_page.java:41)
04-13 22:17:14.869: E/AndroidRuntime(25692):    at android.app.Activity.performCreate(Activity.java:5122)
04-13 22:17:14.869: E/AndroidRuntime(25692):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1146)
04-13 22:17:14.869: E/AndroidRuntime(25692):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2328)
04-13 22:17:14.869: E/AndroidRuntime(25692):    ... 11 more

请帮我弄清楚我的代码有什么问题。在此先感谢!!

Answer 1

您的主题是误导性的。您的stacktrace中的例外是

Couldn't read row 0, col -1 from CursorWindow

这实质上意味着getColumnIndex()找不到Cursor中的指定列，并且-1作为列索引返回。

您的选择SELECT *包含表格中的所有列。

您的CREATE TABLE似乎包含了getColumnIndex()中getNotes()请求索引的所有列。

您可能已经添加了一个列，但测试设备仍然有一个没有该列的数据库文件。只需卸载您的应用程序或清除其数据即可删除旧数据库文件，并使onCreate()在下次运行时重新创建数据库。

Answer 2

表中的列名与您在代码中访问该列时使用的名称之间可能存在差异。所以你应该重新检查这个名字，因为在我的情况下有一个拼写错误：P

java - java.lang.IllegalStateException：无法从CursorWindow读取第0行col -1

2 个答案: