我已从ArrayClass下面的Database成功添加了数据
public class DBHelper {
private final String DATABASE_PATH = "/data/data/../databases/";
private final String DATABASE_NAME = "...sqlite";
private final static int DATABASE_VERSION = 1;
private Context context;
private SQLiteDatabase database = null;
OpenHelper openHelper=null;
StringBuilder query =null;
Cursor cursor=null;
ArticlesTable articlesTable=new ArticlesTable();
DestinateurTable destinataireTable = new DestinateurTable();
public static DBHelper dbHelper = null;
private DBHelper(Context context) {
this.context = context;
openHelper = new OpenHelper(this.context);
this.database = openHelper.getWritableDatabase();
try {
createDataBase();
openDataBase();
} catch (IOException e) {
e.printStackTrace();
}
}
public static DBHelper getInstance(Context context)
{
if(dbHelper == null)
dbHelper = new DBHelper(context);
return dbHelper;
}
public void openDataBase() throws SQLException{
//Open the database
String myPath = DATABASE_PATH + DATABASE_NAME;
database = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READWRITE);
}
/**
* Creates a empty database on the system and rewrites it with your own database.
* */
public void createDataBase() throws IOException
{
openHelper.getReadableDatabase();
if(getDBAlreadyCopiedToDeviceOnceFlag(context) == false){
try {
copyDataBase();
setDBAlreadyCopiedToDeviceOnceFlag(context);
} catch (IOException e) {
e.printStackTrace();
throw new Error("Error copying database");
}
}
}
/**
* Check if the database already exist to avoid re-copying the file each time you open the application.
* @return true if it exists, false if it doesn't
*/
@SuppressWarnings("unused")
private boolean checkDataBase(){
SQLiteDatabase checkDB = null;
try{
String myPath = DATABASE_PATH + DATABASE_NAME;
checkDB = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READWRITE);
}catch(SQLiteException e){
//database does't exist yet.
}
if(checkDB != null){
checkDB.close();
}
return checkDB != null ? true : false;
}
/**
* Copies your database from your local assets-folder to the just created empty database in the
* system folder, from where it can be accessed and handled.
* This is done by transfering bytestream.
* */
private void copyDataBase() throws IOException{
//Open your local db as the input stream
InputStream myInput = context.getAssets().open(DATABASE_NAME);
// Path to the just created empty db
String outFileName = DATABASE_PATH + DATABASE_NAME;
//Open the empty db as the output stream
OutputStream myOutput = new FileOutputStream(outFileName);
//transfer bytes from the inputfile to the outputfile
byte[] buffer = new byte[1024];
int length;
while ((length = myInput.read(buffer))>0){
myOutput.write(buffer, 0, length);
}
//Close the streams
myOutput.flush();
myOutput.close();
myInput.close();
}
private class OpenHelper extends SQLiteOpenHelper
{
@SuppressWarnings("unused")
SQLiteStatement insertStmt;
public OpenHelper(Context context)
{
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db)
{
// TODO Auto-generated method stub
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion)
{
// TODO Auto-generated method stub
}
}
public void setDBAlreadyCopiedToDeviceOnceFlag(Context ctx)
{
SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(ctx);
SharedPreferences.Editor editor = prefs.edit();
editor.putBoolean("isDBAlreadyCopiedToDeviceOnce", true);
editor.commit();
}
public boolean getDBAlreadyCopiedToDeviceOnceFlag(Context ctx)
{
SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(ctx);
boolean isDBAlreadyCopiedToDeviceOnce = prefs.getBoolean("isDBAlreadyCopiedToDeviceOnce", false);
return isDBAlreadyCopiedToDeviceOnce;
}
////////////////////////////
//// Write your methods here
////////////////////////////
public ArrayList<Article> getArticlesList(){
ArrayList<Article> items=new ArrayList<Article>();
try
{
query = new StringBuilder();
query.append("select * from "+articlesTable.TABLE_NAME);
cursor=this.database.rawQuery(query.toString(),null);
if (cursor.moveToFirst())
{
do
{
Article a=new Article();
a.enseigne=cursor.getString(cursor.getColumnIndex(articlesTable.ENSEIGNE));
a.tel=cursor.getString(cursor.getColumnIndex(articlesTable.TEL));
a.fax=cursor.getString(cursor.getColumnIndex(articlesTable.FAX));
a.latitude=cursor.getString(cursor.getColumnIndex(articlesTable.LATITUDE));
a.longitude=cursor.getString(cursor.getColumnIndex(articlesTable.LONGITUDE));
a.adresse1=cursor.getString(cursor.getColumnIndex(articlesTable.ADRESSE1));
a.adresse2=cursor.getString(cursor.getColumnIndex(articlesTable.ADRESSE2));
a.adresse3=cursor.getString(cursor.getColumnIndex(articlesTable.ADRESSE3));
a.adresse4=cursor.getString(cursor.getColumnIndex(articlesTable.ADRESSE4));
a.adresse5=cursor.getString(cursor.getColumnIndex(articlesTable.ADRESSE5));
a.adresse6=cursor.getString(cursor.getColumnIndex(articlesTable.ADRESSE6));
a.horaires1=cursor.getString(cursor.getColumnIndex(articlesTable.HORAIRE1));
a.horaires2=cursor.getString(cursor.getColumnIndex(articlesTable.HORAIRE2));
a.horaires3=cursor.getString(cursor.getColumnIndex(articlesTable.HORAIRE3));
a.horaires4=cursor.getString(cursor.getColumnIndex(articlesTable.HORAIRE4));
a.horaires5=cursor.getString(cursor.getColumnIndex(articlesTable.HORAIRE5));
a.horaires6=cursor.getString(cursor.getColumnIndex(articlesTable.HORAIRE6));
a.horaires7=cursor.getString(cursor.getColumnIndex(articlesTable.HORAIRE7));
items.add(a);
System.out.println("added_items:"+items);
}
while (cursor.moveToNext());
}
if (cursor != null && !cursor.isClosed())
{
cursor.close();
}
}
catch(SQLiteException e){
e.printStackTrace();
return null;
}
return items;
}
//--here
public boolean addArticle(Article a){
this.database.beginTransaction();
try{
ContentValues contentValues=new ContentValues();
contentValues.put(articlesTable.ENSEIGNE, a.enseigne);
contentValues.put(articlesTable.TEL, a.tel);
contentValues.put(articlesTable.FAX, a.fax);
contentValues.put(articlesTable.LATITUDE, a.latitude);
contentValues.put(articlesTable.LONGITUDE, a.longitude);
contentValues.put(articlesTable.ADRESSE1, a.adresse1);
contentValues.put(articlesTable.ADRESSE2, a.adresse2);
contentValues.put(articlesTable.ADRESSE3, a.adresse3);
contentValues.put(articlesTable.ADRESSE4, a.adresse4);
contentValues.put(articlesTable.ADRESSE5, a.adresse5);
contentValues.put(articlesTable.ADRESSE6, a.adresse6);
contentValues.put(articlesTable.HORAIRE1, a.horaires1);
contentValues.put(articlesTable.HORAIRE2, a.horaires2);
contentValues.put(articlesTable.HORAIRE3, a.horaires3);
contentValues.put(articlesTable.HORAIRE4, a.horaires4);
contentValues.put(articlesTable.HORAIRE5, a.horaires5);
contentValues.put(articlesTable.HORAIRE6, a.horaires6);
contentValues.put(articlesTable.HORAIRE7, a.horaires7);
this.database.insert(articlesTable.TABLE_NAME,null,contentValues);
this.database.setTransactionSuccessful();
}catch(Exception e){
e.printStackTrace();
return false;
}finally{
this.database.endTransaction();
}
return true;
}
public boolean deleteArticle(String id){
try
{
String query="delete from " + articlesTable.TABLE_NAME+" where "+articlesTable.NOM+"='"+id+"'";
this.database.execSQL(query);
}
catch(SQLiteException e){
e.printStackTrace();
return false;
}
return true;
}
在上面的代码中，Article a=new Article();是一个包含以下值的类：
public class Article {
public String enseigne, type,nom,latitude,longitude,
tel,fax,adresse1,adresse2,adresse3,adresse4,adresse5,
adresse6,horaires1,horaires2,horaires3,horaires4,horaires5,
horaires6,horaires7 ;
}
在我的MainActivity.class onCreate()方法中。我想打印名字。我怎样才能做到这一点
在MainActivity.class我初始化Article，如跟随Article a = new Article();，然后致电a.name，但这不是方法。
答案 0 :(得分：0)
您正在使用Article a = new Article()创建新实例，因此新对象的所有String变量均为null。
在MainActivity中调用DbHelper类方法getArticlesList()并获取方法ArrayList的{{1}}。然后你可以使用returns和其他人......
希望这会有所帮助......
答案 1 :(得分：0)
1）在你的onCreate（）中，你想要实现你的DBHelper类
DBHelper dbhelper = new DBHelper();
2）在onCreate（）中，你将调用getArticlesList（）
ArrayList<Article> mArticles = dbhelper.getArticlesList();
3）当您想要使用文章时，只需按索引获取您想要的文章：
Article = mArticles.get(x);
这应该是你所需要的。