關閉仿真器後數據庫丟失數據

我的程序包含一個數據庫類。我從數據庫檢索數據到列表視圖和代碼works.But當我關閉模擬器並重新打開它所有的數據都丟失。給出數據庫類。請幫助我對數據持久性的代碼進行必要的更改。關閉仿真器後數據庫丟失數據

classdbOpenHelper.java

package example.events1; 

import android.content.Context; 
import android.database.Cursor; 
import android.database.SQLException; 
import android.database.sqlite.SQLiteDatabase; 
import android.database.sqlite.SQLiteOpenHelper; 


public class classdbOpenHelper extends SQLiteOpenHelper { 

    public static final String KEY_ROWID = "_id"; 
    public static final String KEY_DESC = "countdesc"; 
    public static final String KEY_DATE = "countdate"; 
    public static final String KEY_EVENT = "countevent"; 
    public static final String DATABASE_NAME= "countdb"; 
    public static final String DATABASE_TABLE = "countable"; 
    public static final int DATABASE_VERSION = 1; 


    public classdbOpenHelper(Context context) { 
     super(context, DATABASE_NAME, null, DATABASE_VERSION); 
     // TODO Auto-generated constructor stub 
    } 

    @Override 
    public void onCreate(SQLiteDatabase db) { 

     String CREATE_CONTACTS_TABLE = "CREATE TABLE " + DATABASE_TABLE + "(" 
       + KEY_ROWID + " INTEGER PRIMARY KEY AUTOINCREMENT, " + KEY_DESC + " TEXT, " + KEY_DATE + " TEXT, " + KEY_EVENT + " TEXT )"; 
     db.execSQL(CREATE_CONTACTS_TABLE); 
    } 


    @Override 
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { 
     // TODO Auto-generated method stub 
     db.execSQL("DROP TABLE IF EXITS " + DATABASE_TABLE); 
     onCreate(db); 

    } 


    public Cursor fetchAllEvents() { 
     SQLiteDatabase db = this.getReadableDatabase(); 

     Cursor mCursor = db.query(DATABASE_TABLE, new String[] {KEY_ROWID, 
       KEY_DESC, KEY_DATE, KEY_EVENT }, 
     null, null, null, null, null); 
     if (mCursor != null) { 
     mCursor.moveToFirst(); 
     } 
     return mCursor; 
    } 

    public Cursor fetchEventByName(String inputText,String datevalue) throws SQLException { 
     SQLiteDatabase db = this.getReadableDatabase(); 

     Cursor mCursor = null; 
     if (inputText == null || inputText.length() == 0) { 
     mCursor = db.query(DATABASE_TABLE, new String[] {KEY_ROWID, 
       KEY_DESC, KEY_DATE, KEY_EVENT }, 
     null, null, null, null, null); 
     } 
     else { 
      mCursor = db.rawQuery("SELECT * FROM countable WHERE countdesc = ? AND countdate = ?", new String[] {inputText,datevalue});   
     } 

     if (mCursor != null) { 
     mCursor.moveToFirst(); 
     } 
     return mCursor; 
    } 

    public void delete(long id) { 
     SQLiteDatabase db = this.getReadableDatabase(); 

     db.delete(DATABASE_TABLE, KEY_ROWID + " = ?", 
       new String[] { String.valueOf(id)}); 
     db.close(); 
    } 
}

來源

2013-08-17 user2681154

當您重新打開模擬器時，取消選中「擦除用戶數據」選項（如果選中）。 – TheFlash

@Indiandroid在這個選項在月食 – user2681154

檢查奧馬爾的答案你必須改變你的代碼..它在工具欄（安卓設備管理器） – TheFlash

變化

String CREATE_CONTACTS_TABLE = "CREATE TABLE " + DATABASE_TABLE + "(" + KEY_ROWID + " INTEGER PRIMARY KEY AUTOINCREMENT, " + KEY_DESC + " TEXT, " + KEY_DATE + " TEXT, " + KEY_EVENT + " TEXT )";

要

String CREATE_CONTACTS_TABLE = "CREATE TABLE IF NOT EXISTS" + DATABASE_TABLE + "(" + KEY_ROWID + " INTEGER PRIMARY KEY AUTOINCREMENT, " + KEY_DESC + " TEXT, " + KEY_DATE + " TEXT, " + KEY_EVENT + " TEXT )";

的原因，你的數據庫是空的，只要你app/activity被完全破壞（即，當手機/仿真器重新啓動），是因爲you haven't specified the conditions用於何時創建數據庫和何時不是。通過進行上述更改，您的問題應該早已消失

來源

2013-08-17 12:59:33

如果你的問題得到解決。請接受答案。 –

無法正常工作......... – user2681154

@UmerFarooq錯誤的答案，如果你需要做「CREATE TABLE IF NOT EXISTS」這意味着你的編程（代碼結構）是不好的......實際上，如果你正確地設計你的數據庫代碼，您不需要考慮表格是否存在 –

關閉仿真器後數據庫丟失數據

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