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[英]In Android how to fetch the contacts and save to database implements?
[英]How to save database in Android?
我是android開發的新手,我正在嘗試制作一個簡單的應用程序,可以在其中添加和查看記錄。 我可以成功添加數據並在表中查看它們,每次運行程序時它都可以工作。 (我正在學習本教程 )但是每次我關閉Eclipse並嘗試添加新數據並查看它們時,我輸入的先前信息都消失了。 似乎當我關閉Eclipse時,它不會保存我的數據庫。 這是我關注的示例代碼。
package com.example.hotornot;
import java.sql.Statement;
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 Example {
public static final String KEY_ROWID = "id";
public static final String KEY_NAME = "name";
public static final String KEY_NUM = "number";
public static final String DATABASE_NAME = "dbTry";
public static final String DATABASE_TABLE = "tblSamp";
public static final int DATABASE_VERSION = 1;
public DbHelper ourhelper;
public final Context ourcontext;
public SQLiteDatabase ourdatabase;
class DbHelper extends SQLiteOpenHelper{
public DbHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
// TODO Auto-generated constructor stub
}
@Override
public void onCreate(SQLiteDatabase arg0) {
// TODO Auto-generated method stub
arg0.execSQL("CREATE TABLE " + DATABASE_TABLE + " (" + KEY_ROWID + " INTEGER, " + KEY_NAME + " NULL, " + KEY_NUM + " NULL);");
}
@Override
public void onUpgrade(SQLiteDatabase arg0, int arg1, int arg2) {
// TODO Auto-generated method stub
arg0.execSQL("DROP TABLE IF EXIST " + DATABASE_TABLE);
onCreate(arg0);
}
}
public Example(Context c)
{
ourcontext = c;
}
public Example open() throws SQLException
{
ourhelper = new DbHelper(ourcontext);
ourdatabase = ourhelper.getWritableDatabase();
return this;
}
public void close()
{
ourhelper.close();
}
public long createEntry(String name, String num)
{
// TODO Auto-generated method stub
ContentValues cv = new ContentValues();
cv.put(KEY_NAME, name);
cv.put(KEY_NUM, num);
return ourdatabase.insert(DATABASE_TABLE, null, cv);
}
public String getData()
{
// TODO Auto-generated method stub
String[] columns = new String[]{ KEY_ROWID,KEY_NAME, KEY_NUM};
Cursor c = ourdatabase.query(DATABASE_TABLE, columns, null, null, null, null, null);
String result = "";
int iRow = c.getColumnIndex(KEY_ROWID);
int iName = c.getColumnIndex(KEY_NAME);
int iNum = c.getColumnIndex(KEY_NUM);
for (c.moveToFirst(); ! c.isAfterLast(); c.moveToNext()){
result = result + c.getString(iRow) + " " +c.getString(iName) + " " + c.getString(iNum) + "\n";
}
return result;
}
}
您必須覆蓋現有數據庫或卸載應用程序
請檢查您的代碼
在Activity onCreate事件上檢查是否存在db文件(如果存在)不要覆蓋並跳過該過程,您肯定會得到舊記錄
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