Sqlite不会保存数据添加

Question

我正在做一个应用程序，它需要一个SQLite数据库。我可以添加数据并查看它，但在每次重新启动应用程序时，关闭，重新打开数据会被删除。这是为什么？

DB处理程序：

package com.spxc.wakeuptext.sql; 

import java.util.ArrayList; 
import java.util.List; 

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

public class DatabaseHandler extends SQLiteOpenHelper { 

    // All Static variables 
    // Database Version 
    private static final int DATABASE_VERSION = 1; 

    // Database Name 
    private static final String DATABASE_NAME = "contactsManager"; 

    // Contacts table name 
    public static final String TABLE_CONTACTS = "contacts"; 

    // Contacts Table Columns names 
    private static final String KEY_ID = "id"; 
    private static final String KEY_NAME = "name"; 
    private static final String KEY_PH_NO = "phone_number"; 

    public DatabaseHandler(Context context) { 
     super(context, DATABASE_NAME, null, DATABASE_VERSION); 
    } 

    // Creating Tables 
    @Override 
    public void onCreate(SQLiteDatabase db) { 
     String CREATE_CONTACTS_TABLE = "CREATE TABLE " + TABLE_CONTACTS + "(" 
       + KEY_ID + " INTEGER PRIMARY KEY," + KEY_NAME + " TEXT," 
       + KEY_PH_NO + " TEXT" + ")"; 
     db.execSQL(CREATE_CONTACTS_TABLE); 
    } 

    // Upgrading database 
    @Override 
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { 
     // Drop older table if existed 
     db.execSQL("DROP TABLE IF EXISTS " + TABLE_CONTACTS); 

     // Create tables again 
     onCreate(db); 
    } 

    /** 
    * All CRUD(Create, Read, Update, Delete) Operations 
    */ 

    public // Adding new contact 
    void addContact(WhiteList contact) { 
     SQLiteDatabase db = this.getWritableDatabase(); 

     ContentValues values = new ContentValues(); 
     values.put(KEY_NAME, contact.getName()); // Contact Name 
     values.put(KEY_PH_NO, contact.getPhoneNumber()); // Contact Phone 

     // Inserting Row 
     db.insert(TABLE_CONTACTS, null, values); 
     db.close(); // Closing database connection 
    } 

    // Getting single contact 
    WhiteList getContact(int id) { 
     SQLiteDatabase db = this.getReadableDatabase(); 

     Cursor cursor = db.query(TABLE_CONTACTS, new String[] { KEY_ID, 
       KEY_NAME, KEY_PH_NO }, KEY_ID + "=?", 
       new String[] { String.valueOf(id) }, null, null, null, null); 
     if (cursor != null) 
      cursor.moveToFirst(); 

     WhiteList contact = new WhiteList(Integer.parseInt(cursor.getString(0)), 
       cursor.getString(1), cursor.getString(2)); 
     // return contact 
     return contact; 
    } 

    // Getting All Contacts 
    public List<WhiteList> getAllContacts() { 
     List<WhiteList> contactList = new ArrayList<WhiteList>(); 
     // Select All Query 
     String selectQuery = "SELECT * FROM " + TABLE_CONTACTS; 

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

     // looping through all rows and adding to list 
     if (cursor.moveToFirst()) { 
      do { 
       WhiteList contact = new WhiteList(); 
       contact.setID(Integer.parseInt(cursor.getString(0))); 
       contact.setName(cursor.getString(1)); 
       contact.setPhoneNumber(cursor.getString(2)); 
       // Adding contact to list 
       contactList.add(contact); 
      } while (cursor.moveToNext()); 
     } 

     // return contact list 
     return contactList; 
    } 

    // Updating single contact 
    public int updateContact(WhiteList contact) { 
     SQLiteDatabase db = this.getWritableDatabase(); 

     ContentValues values = new ContentValues(); 
     values.put(KEY_NAME, contact.getName()); 
     values.put(KEY_PH_NO, contact.getPhoneNumber()); 

     // updating row 
     return db.update(TABLE_CONTACTS, values, KEY_ID + " = ?", 
       new String[] { String.valueOf(contact.getID()) }); 
    } 

    // Deleting single contact 
    public void deleteContact(WhiteList contact) { 
     SQLiteDatabase db = this.getWritableDatabase(); 
     db.delete(TABLE_CONTACTS, KEY_ID + " = ?", 
       new String[] { String.valueOf(contact.getID()) }); 
     db.close(); 
    } 


    // Getting contacts Count 
    public int getContactsCount() { 
     String countQuery = "SELECT * FROM " + TABLE_CONTACTS; 
     SQLiteDatabase db = this.getReadableDatabase(); 
     Cursor cursor = db.rawQuery(countQuery, null); 
     cursor.close(); 

     // return count 
     return cursor.getCount(); 
    } 

} 

我有我的活动被添加在启动时1个记录只是有东西在那里。我的活动/片段：

package com.spxc.wakeuptext.frag; 

import java.util.ArrayList; 
import java.util.List; 

import android.app.AlertDialog; 
import android.app.Dialog; 
import android.app.AlertDialog.Builder; 
import android.content.Context; 
import android.content.DialogInterface; 
import android.database.Cursor; 
import android.database.sqlite.SQLiteDatabase; 
import android.database.sqlite.SQLiteException; 
import android.os.Bundle; 
import android.util.Log; 
import android.view.LayoutInflater; 
import android.view.View; 
import android.view.ViewGroup; 
import android.view.inputmethod.InputMethodManager; 
import android.widget.ArrayAdapter; 
import android.widget.EditText; 
import android.widget.LinearLayout; 
import android.widget.TextView; 
import android.widget.Toast; 

import com.actionbarsherlock.app.SherlockListFragment; 
import com.actionbarsherlock.view.Menu; 
import com.actionbarsherlock.view.MenuInflater; 
import com.actionbarsherlock.view.MenuItem; 
import com.spxc.wakeuptext.R; 
import com.spxc.wakeuptext.sql.DatabaseHandler; 
import com.spxc.wakeuptext.sql.WhiteList; 

public class Fragment_2 extends SherlockListFragment{ 

    private ArrayList<String> results = new ArrayList<String>(); 
    private String tableName = DatabaseHandler.TABLE_CONTACTS; 
    private SQLiteDatabase newDB; 
    private static final int ADD = 1; 

    @Override 
    public View onCreateView(LayoutInflater inflater, ViewGroup container, 
      Bundle savedInstanceState) { 
     setHasOptionsMenu(true); 
     View v = inflater.inflate(R.layout.fragment_2, null);  
     return v;  
    } 

    public void onActivityCreated(Bundle savedInstanceState) { 
     super.onActivityCreated(savedInstanceState); 

     DatabaseHandler db = new DatabaseHandler(getActivity()); 
     db.addContact(new WhiteList("Ravi", "9100000000")); 

     openAndQueryDatabase(); 
     displayResultList(); 
    } 

    private void openAndQueryDatabase() { 
     try { 
      DatabaseHandler dbHelper = new DatabaseHandler(getActivity().getApplicationContext()); 
      newDB = dbHelper.getWritableDatabase(); 
      Cursor c = newDB.rawQuery("SELECT name, phone_number FROM " + 
        tableName, null); 

      if (c != null) { 
       if (c.moveToFirst()) { 
        do { 
         String firstName = c.getString(c.getColumnIndex("name")); 
         int age = c.getInt(c.getColumnIndex("phone_number")); 
         results.add("Name: " + firstName + ",Pne: " + age); 
        }while (c.moveToNext()); 
       } 
      }   
     } catch (SQLiteException se) { 
      Log.e(getClass().getSimpleName(), "Could not create or Open the database"); 
     } finally { 
      if (newDB != null) 
       newDB.execSQL("DELETE FROM " + tableName); 
       newDB.close(); 
     } 

    } 

    private void displayResultList() { 
     TextView tView = new TextView(getActivity()); 
     tView.setText("This data is retrieved from the database and only 4 " + 
       "of the results are displayed"); 
     getListView().addHeaderView(tView); 

     setListAdapter(new ArrayAdapter<String>(getActivity(), 
       android.R.layout.simple_list_item_1, results)); 

     getListView().setTextFilterEnabled(true); 

    } 

    @Override 
    public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) { 
     super.onCreateOptionsMenu(menu, inflater); 
     MenuItem search = menu.add(0, ADD, 0, "Refresh"); 
     search.setIcon(android.R.drawable.ic_menu_add); 
     search.setShowAsAction(MenuItem.SHOW_AS_ACTION_IF_ROOM); 
    } 

    @Override 
    public boolean onOptionsItemSelected(MenuItem item) { 
     switch (item.getItemId()) { 
      case ADD: 
       addNumber(); 
       return true; 
      default: 
       return super.onOptionsItemSelected(item); 
     } 
    } 

    public void addNumber(){ 
     LayoutInflater factory = LayoutInflater.from(getActivity()); 

     final View textEntryView = factory.inflate(R.layout.text_entry, null); 

     final EditText name = (EditText) textEntryView.findViewById(R.id.editText1); 
     final EditText phone = (EditText) textEntryView.findViewById(R.id.editText2); 

     name.setHint("Name"); 
     phone.setHint("Phone Number"); 

     final AlertDialog.Builder alert = new AlertDialog.Builder(getActivity()); 
     alert.setTitle(
      "Contact information").setView(
      textEntryView).setPositiveButton("Save", 
      new DialogInterface.OnClickListener() { 
      public void onClick(DialogInterface dialog, 
      int whichButton) { 
       DatabaseHandler db = new DatabaseHandler(getActivity()); 
       db.addContact(new WhiteList(name.getText().toString(), phone.getText().toString())); 
       openAndQueryDatabase(); 
       displayResultList(); 
      } 
      }).setNegativeButton("Cancel", 
      new DialogInterface.OnClickListener() { 
      public void onClick(DialogInterface dialog, 
      int whichButton) { 
      /* 
      * User clicked cancel so do some stuff 
      */ 
      } 
      }); 
     alert.show(); 
    } 
} 

为什么我的数据库数据没有保存？我正在真实设备上运行应用程序。所有数据在重新打开应用程序时被删除。任何帮助深表感谢！

Answer 1

这是因为您要删除表中的所有记录在每一个openAndQueryDatabase（）

finally { 
     if (newDB != null) 
      newDB.execSQL("DELETE FROM " + tableName); 
      newDB.close(); 
    } 

Answer 2

我猜你的再次再次重新创建数据库..every时间申请 开始

Answer 3

是的，因为在创建数据库的代码是在onCreate方法。

public void onCreate(SQLiteDatabase db) { 
    String CREATE_CONTACTS_TABLE = "CREATE TABLE " + TABLE_CONTACTS + "(" 
      + KEY_ID + " INTEGER PRIMARY KEY," + KEY_NAME + " TEXT," 
      + KEY_PH_NO + " TEXT" + ")"; 
    db.execSQL(CREATE_CONTACTS_TABLE); 
}