Question

我在数据库文件中遇到上述错误。我是编码的新手。请帮我解决这个问题。我不知道这些类型的问题。请给我建议。

我的数据库代码如下所示：

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;
            }
        }

}

我观察到的logcat痕迹如下所示：

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

请帮帮我。

Answer 1

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

您的光标不包含任何数据

您需要像这样验证Cursor。如果您的光标数大于0，那么只需要从光标中获取数据。

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 2

问题在于您的getUser功能。

也许您的cursor不为空，但它仍然可能为空：

尝试以下方法：

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;

}

希望有所帮助

Answer 3

首先检查是否存在数据

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

然后需要从光标的^th位置读取数据

更改此

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

到

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

错误 - 无法启动活动ComponentInfo：android.database.CursorIndexOutOfBoundsException：请求索引0，大小为0

3 个答案: