錯誤 - 無法啓動活動ComponentInfo：android.database.CursorIndexOutOfBoundsException：索引0請求，大小爲0

Question

我在數據庫文件中出現以上錯誤。我是編碼新手。請幫我解決這個問題。我不瞭解這些類型的問題。請給我建議。

我的數據庫代碼如下所示：

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

public class DatabaseHandler extends SQLiteOpenHelper{ 

    // Database Version 
    private static final int DATABASE_VERSION = 1; 
    // Database Name 
    private static final String DATABASE_NAME = "applicationDB"; 
    // Employee table name 
    private static final String TABLE_USERS = "apps"; 

    private static String SlNo = "slno"; 
    private static String NAME = "name"; 
    private static String PHONE = "phone"; 
    private static String EMAIL = "email"; 
    private static String ADDRESS = "address"; 
    private static String COMMENTS = "comments"; 
    public DatabaseHandler(Context context) { 
     super(context, DATABASE_NAME, null, DATABASE_VERSION); 
    } 

    @Override 
    public void onCreate(SQLiteDatabase db) { 
     String CREATE_USER_TABLE = " CREATE TABLE " + TABLE_USERS + "(" 
       + SlNo + " INTEGER PRIMARY KEY, " 
       + NAME + " TEXT, " 
       + PHONE + " TEXT, " 
       + EMAIL + " TEXT, " 
       + ADDRESS + " TEXT, " 
       + COMMENTS + " TEXT " 
       + ")"; 
     db.execSQL(CREATE_USER_TABLE); 
     //db.close(); 

    } 

    @Override 
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { 
     // Drop older table if existed 
     Log.e(NAME, "Error is here"); 
     Log.e(PHONE, "Error is here"); 
     Log.e(EMAIL, "Error is here"); 
     Log.e(ADDRESS, "Error is here"); 
     Log.e(COMMENTS, "Error is here"); 
     db.execSQL(" DROP TABLE IF EXISTS " + TABLE_USERS); 
     // Create tables again 
     onCreate(db); 

    } 

    // Adding new user 
    public int addUser(User user) 
    { 
     SQLiteDatabase db = this.getWritableDatabase(); 
     ContentValues values = new ContentValues(); 
     values.put(NAME, user.getName()); 
     values.put(ADDRESS, user.getAddress()); 
     values.put(PHONE, user.getPhone()); 
     values.put(EMAIL, user.getEmail()); 
     values.put(COMMENTS, user.getComments()); 
     // Inserting Row 
     int id = (int) db.insert(TABLE_USERS, null, values); 
     db.close(); // Closing database connection 
     return id; 
    } 

    //updating a existing user 
    public int editUser(User user, String position) { 
      SQLiteDatabase db = this.getWritableDatabase(); 
      ContentValues values = new ContentValues(); 
      values.put(NAME, user.getName()); 
      values.put(ADDRESS, user.getAddress()); 
      values.put(PHONE, user.getPhone()); 
      values.put(EMAIL, user.getEmail()); 
      values.put(COMMENTS, user.getComments()); 
      // updating row 
      return db.update(TABLE_USERS, values, SlNo + " = ?", 
        new String[] { String.valueOf(position) }); 
    } 

    public User getUser(String id) { 
     SQLiteDatabase db = this.getReadableDatabase(); 
     Cursor cursor = db.query(TABLE_USERS, new String[] { 
       SlNo, NAME, ADDRESS, PHONE, EMAIL, COMMENTS }, SlNo + "=?", 
       new String[] {String.valueOf(id)}, null, null, null, null); 
     if (cursor != null) 
      cursor.moveToFirst(); 

     User user = new User(cursor.getString(1), 
       cursor.getString(2), cursor.getString(3), cursor.getString(4), cursor.getString(5)); 
     db.close(); 
     // return user 
     return user; 

    } 

     // LIst all users 
     public String[] getAllUsers() { 
      ArrayList<String> usersList = new ArrayList<String>(); 
      Log.e(NAME, "Error is here"); 
      Log.e(PHONE, "Error is here"); 
      Log.e(EMAIL, "Error is here"); 
      Log.e(ADDRESS, "Error is here"); 
      Log.e(COMMENTS, "Error is here"); 
      String selectQuery = " SELECT * FROM " + TABLE_USERS; 
      try { 
       SQLiteDatabase db = this.getReadableDatabase(); 
       Cursor cursor = db.rawQuery(selectQuery, null); 
       // looping through all rows and adding to list 
       if (cursor.moveToFirst()) { 
        do { 
         String user = cursor.getString(1) + ", " + cursor.getString(2) + ", " + cursor.getString(3) + ", " + cursor.getString(4) + ", " + cursor.getString(5); 
         usersList.add(user); 
        } while (cursor.moveToNext()); 
       } 

       String[] users = new String[usersList.size()]; 
       db.close(); 
       return (usersList.toArray(users)); 
      } 
      catch(Exception e) { 
       Log.d("Error in getting users from DB", e.getMessage()); 
       return null; 
      } 
     } 

} 

由我所觀察到的logcat的痕跡，如下圖所示：

12-23 04:12:29.037: D/value of position from intent(3072): null 
12-23 04:12:29.407: D/AndroidRuntime(3072): Shutting down VM 
12-23 04:12:29.427: W/dalvikvm(3072): threadid=1: thread exiting with uncaught exception (group=0xb0f5e648) 
12-23 04:12:29.487: E/AndroidRuntime(3072): FATAL EXCEPTION: main 
12-23 04:12:29.487: E/AndroidRuntime(3072): java.lang.RuntimeException: Unable to start activity ComponentInfo{form.app.applicationform1/form.app.applicationform1.DetailsUsers}: android.database.CursorIndexOutOfBoundsException: Index 0 requested, with a size of 0 
12-23 04:12:29.487: E/AndroidRuntime(3072):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2211) 
12-23 04:12:29.487: E/AndroidRuntime(3072):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2261) 
12-23 04:12:29.487: E/AndroidRuntime(3072):  at android.app.ActivityThread.access$600(ActivityThread.java:141) 
12-23 04:12:29.487: E/AndroidRuntime(3072):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1256) 
12-23 04:12:29.487: E/AndroidRuntime(3072):  at android.os.Handler.dispatchMessage(Handler.java:99) 
12-23 04:12:29.487: E/AndroidRuntime(3072):  at android.os.Looper.loop(Looper.java:137) 
12-23 04:12:29.487: E/AndroidRuntime(3072):  at android.app.ActivityThread.main(ActivityThread.java:5103) 
12-23 04:12:29.487: E/AndroidRuntime(3072):  at java.lang.reflect.Method.invokeNative(Native Method) 
12-23 04:12:29.487: E/AndroidRuntime(3072):  at java.lang.reflect.Method.invoke(Method.java:525) 
12-23 04:12:29.487: E/AndroidRuntime(3072):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737) 
12-23 04:12:29.487: E/AndroidRuntime(3072):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553) 
12-23 04:12:29.487: E/AndroidRuntime(3072):  at dalvik.system.NativeStart.main(Native Method) 
12-23 04:12:29.487: E/AndroidRuntime(3072): Caused by: android.database.CursorIndexOutOfBoundsException: Index 0 requested, with a size of 0 
12-23 04:12:29.487: E/AndroidRuntime(3072):  at android.database.AbstractCursor.checkPosition(AbstractCursor.java:424) 
12-23 04:12:29.487: E/AndroidRuntime(3072):  at android.database.AbstractWindowedCursor.checkPosition(AbstractWindowedCursor.java:136) 
12-23 04:12:29.487: E/AndroidRuntime(3072):  at android.database.AbstractWindowedCursor.getString(AbstractWindowedCursor.java:50) 
12-23 04:12:29.487: E/AndroidRuntime(3072):  at form.app.applicationform1.DatabaseHandler.getUser(DatabaseHandler.java:97) 
12-23 04:12:29.487: E/AndroidRuntime(3072):  at form.app.applicationform1.DetailsUsers.onCreate(DetailsUsers.java:42) 
12-23 04:12:29.487: E/AndroidRuntime(3072):  at android.app.Activity.performCreate(Activity.java:5133) 
12-23 04:12:29.487: E/AndroidRuntime(3072):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087) 
12-23 04:12:29.487: E/AndroidRuntime(3072):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2175) 
12-23 04:12:29.487: E/AndroidRuntime(3072):  ... 11 more 
12-23 04:14:59.689: I/Process(3072): Sending signal. PID: 3072 SIG: 9 

請幫助我。

Answer 1

問題是您的getUser函數。

也許你cursor不爲空，但它仍然可能是空的：

嘗試以下操作：

public User getUser(String id) { 
    User user = null; 
    SQLiteDatabase db = this.getReadableDatabase(); 
    Cursor cursor = db.query(TABLE_USERS, new String[] { 
      SlNo, NAME, ADDRESS, PHONE, EMAIL, COMMENTS }, SlNo + "=?", 
      new String[] {String.valueOf(id)}, null, null, null, null); 
    if (cursor != null) 
    { 
     if(cursor.moveToFirst()) 
     { 
      user = new User(cursor.getString(1), 
      cursor.getString(2), cursor.getString(3), cursor.getString(4), cursor.getString(5)); 
     } 
    } 
    db.close(); 
    // return user 
    return user; 

} 

希望它可以幫助

Answer 2

Caused by: android.database.CursorIndexOutOfBoundsException: Index 0 requested, with a size of 0 

你的光標不包含任何數據

您需要像這樣驗證Cursor。如果您的光標數量超過0，那麼只有您需要從光標獲取數據。

public User getUser(String id) { 

    User mUser = null; 
    SQLiteDatabase db = this.getReadableDatabase(); 
    Cursor cursor = db.query(TABLE_USERS, new String[] { SlNo, NAME, ADDRESS, PHONE, EMAIL, COMMENTS }, SlNo + "=?", 
      new String[] { String.valueOf(id) }, null, null, null, null); 
    if (cursor != null && cursor.getCount > 0) { 
     cursor.moveToFirst(); 
     mUser = new User(cursor.getString(cursor.getColumnIndex("NAME")), 
        cursor.getString(cursor.getColumnIndex("ADDRESS")), 
        cursor.getString(cursor.getColumnIndex("PHONE")), 
        cursor.getString(cursor.getColumnIndex("EMAIL")), 
        cursor.getString(cursor.getColumnIndex("COMMENTS"))); 
     cursor.close(); 
    } 
    d.close(); 
    retunr mUser;   
} 

Answer 3

首先檢查與數據是否存在或不喜歡

if (cursor != null && cursor.getCount > 0) { 
} 

然後需要從光標的零^第位置讀取數據

變化這

User user = new User(cursor.getString(1), 
      cursor.getString(2), cursor.getString(3), cursor.getString(4), cursor.getString(5)); 

納入

User user = new User(cursor.getString(0),cursor.getString(1), 
      cursor.getString(2), cursor.getString(3), cursor.getString(4));