数据库未从 Activity 恢复
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【中文标题】数据库未从 Activity 恢复【英文标题】：Database not restored from Activity 【发布时间】：2018-04-10 08:15:57 【问题描述】：我在 android 中遇到了数据库问题。 我想从一个活动中收集数据，然后将它们传输到另一个应该将它们显示到 ListView 中并将它们保存到数据库中的活动。 问题是应用程序只显示列表视图中的第一项，我不知道是否所有数据都保存到数据库中。 当我尝试插入新项目时，应用程序可能会覆盖第一个项目并显示最新的项目。 非常感谢！
public class HomeActivity extends AppCompatActivity
Button addPets;
private ListView mainListView;
private ArrayList<User> listUser;
private ArrayAdapter adapter;
private DBAdapter dbAdapter;
DBOpenHelper myDb;
@Override
protected void onCreate(Bundle savedInstanceState)
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_home);
addPets = (Button)findViewById(R.id.add_friends);
addPets.setOnClickListener(new View.OnClickListener()
@Override
public void onClick(View v)
Intent apriRegistraPet = new Intent(HomeActivity.this, RegisterActivity.class);
startActivity(apriRegistraPet);
);
dbAdapter = DBAdapter.getInstance(this);
mainListView = (ListView)findViewById(R.id.elenco_pets);
listUser = new ArrayList<User>();
adapter = new ArrayAdapter<User>(this, android.R.layout.simple_list_item_1, listUser);
mainListView.setAdapter(adapter);
mainListView.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener()
@Override
public boolean onItemLongClick(AdapterView<?> parent, View view, int position, long id)
onLongClick(position, mainListView);
return true;
);
private void addNewItem(User user)
long idx = dbAdapter.insertUser(user);
user.setId(idx);
listUser.add(0, user);
adapter.notifyDataSetChanged();
private void onLongClick(final int position, final ListView listView)
User user = (User)listView.getItemAtPosition(position);
Toast.makeText(getApplicationContext(), "Deleted Item", Toast.LENGTH_LONG).show();
if(!dbAdapter.deleteUser(user))
return;
listUser.remove(user);
adapter.notifyDataSetChanged();
@Override
protected void onResume()
super.onResume();
dbAdapter.open();
fillData();
Bundle extras = getIntent().getExtras();
if(extras != null)
String nome = extras.getString("Nome");
String razza = extras.getString("Razza");
String sesso = extras.getString("Sesso");
User user = new User(0, nome, razza, sesso, 10, 2000);
addNewItem(user);
public void fillData()
Cursor cursor = dbAdapter.getAllEntries();
this.listUser.clear();
cursor.moveToFirst();
while(!cursor.isAfterLast())
long idx = cursor.getLong(cursor.getColumnIndex(DBContract.AttributiRegistrazione._ID));
String nome = cursor.getString(cursor.getColumnIndex(DBContract.AttributiRegistrazione.NOME));
String razza = cursor.getString(cursor.getColumnIndex(DBContract.AttributiRegistrazione.RAZZA));
String sesso = cursor.getString(cursor.getColumnIndex(DBContract.AttributiRegistrazione.SESSO));
this.listUser.add(0, new User(idx, nome, razza, sesso, 10, 2000));
cursor.moveToNext();
cursor.close();
adapter.notifyDataSetChanged();
这是注册活动
public class RegisterActivity extends AppCompatActivity
ImageButton settaImmagine;
String imgDecodableString;
Spinner sprazza;
Spinner spsesso;
@Override
protected void onCreate(Bundle savedInstanceState)
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_register);
//Clicco V e mette nella listview
ImageButton salva = (ImageButton)findViewById(R.id.button_salva);
salva.setOnClickListener(new View.OnClickListener()
@Override
public void onClick(View v)
final EditText editText = (EditText)findViewById(R.id.name);
sprazza = (Spinner)findViewById(R.id.spinner_razza);
String razza = sprazza.getSelectedItem().toString();
spsesso = (Spinner)findViewById(R.id.spinner_sesso);
String sesso = spsesso.getSelectedItem().toString();
Intent resultIntent = new Intent(RegisterActivity.this, HomeActivity.class);
resultIntent.putExtra("Nome", editText.getText().toString());
resultIntent.putExtra("Razza", razza);
resultIntent.putExtra("Sesso", sesso);
startActivity(resultIntent);
);
DBAdapter 类；
public class DBAdapter
private static final String TAG = "DBAdapter";
private static DBAdapter dbAdapter;
private static DBOpenHelper dbOpenHelper;
private SQLiteDatabase db;
public synchronized static DBAdapter getInstance(Context context)
if(dbAdapter==null)
dbAdapter = new DBAdapter(context.getApplicationContext());
return dbAdapter;
private DBAdapter(Context context) dbOpenHelper = DBOpenHelper.getInstance(context);
public DBAdapter open() throws SQLException
try
db = dbOpenHelper.getWritableDatabase();
catch (SQLException e)
Log.e(TAG, e.toString());
throw e;
return this;
public void close()
db.close();
public long insertUser (User user)
Log.v(TAG, "Inserisci un User to DB: " +user.getNome());
long idx = db.insert(DBContract.AttributiRegistrazione.NOME_TABELLA, null, user.getAsContentValue());
user.setId(idx);
Log.v(TAG, "Added user with ID: "+idx);
return idx;
public boolean deleteUser (User user)
Log.v(TAG, "Removing User: " + user.getClass());
return db.delete(DBContract.AttributiRegistrazione.NOME_TABELLA,
DBContract.AttributiRegistrazione.NOME + "=" + user.getNome(), null) == 1;
public boolean deleteUser(String name)
Log.v(TAG, "Removing user: " + name);
return db.delete(DBContract.AttributiRegistrazione.NOME_TABELLA,
DBContract.AttributiRegistrazione.NOME + "=" + name, null) == 1;
public Cursor getAllEntries()
return db.query(DBContract.AttributiRegistrazione.NOME_TABELLA,
null, null, null, null, null, null);
错误日志
E/SQLiteLog: (1) table Registrazione has no column named Anno_nascita 04-10 13:57:21.142 10175-10175/com.b.uzzo.snappaw E/SQLiteDatabase: Error inserting Anno_nascita=2000 Peso=10.0 Nome=simone Sesso=Maschio Razza=Akita Inu
android.database.sqlite.SQLiteException: table Registrazione has no column named Anno_nascita (code 1): , while compiling: INSERT INTO Registrazione(Anno_nascita,Peso,Nome,Sesso,Razza) VALUES (?,?,?,?,?)
at android.database.sqlite.SQLiteConnection.nativePrepareStatement(Native Method)
at android.database.sqlite.SQLiteConnection.acquirePreparedStatement(SQLiteConnection.java:898)
at android.database.sqlite.SQLiteConnection.prepare(SQLiteConnection.java:509)
at android.database.sqlite.SQLiteSession.prepare(SQLiteSession.java:588)
at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:58)
at android.database.sqlite.SQLiteStatement.<init>(SQLiteStatement.java:31)
at android.database.sqlite.SQLiteDatabase.insertWithOnConflict(SQLiteDatabase.java:1500)
at android.database.sqlite.SQLiteDatabase.insert(SQLiteDatabase.java:1373)
at com.b.uzzo.snappaw.DBAdapter.insertUser(DBAdapter.java:49)
at com.b.uzzo.snappaw.HomeActivity.addNewItem(HomeActivity.java:105)
at com.b.uzzo.snappaw.HomeActivity.onResume(HomeActivity.java:140)
at android.app.Instrumentation.callActivityOnResume(Instrumentation.java:1269)
at android.app.Activity.performResume(Activity.java:6770)
at android.app.ActivityThread.performResumeActivity(ActivityThread.java:3522)
at android.app.ActivityThread.handleResumeActivity(ActivityThread.java:3591)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2825)
at android.app.ActivityThread.-wrap12(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1542)
at android.os.Handler.dispatchMessage(Handler.java:110)
at android.os.Looper.loop(Looper.java:203)
at android.app.ActivityThread.main(ActivityThread.java:6319)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1085)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:946)
但它是在 DBContract 类中创建的
public class DBContract
static final String DB_NAME = "RegistrazioneCuccioli";
static final int DB_VERSION = 1;
static abstract class AttributiRegistrazione implements BaseColumns
static final String NOME_TABELLA = "Registrazione";
static final String NOME = "Nome";
static final String RAZZA = "Razza";
static final String SESSO = "Sesso";
static final String PESO = "Peso";
static final String ANNO_NASCITA = "Anno_nascita";
【问题讨论】：
你能描述一下dbAdapter.insertUser(user);吗？
'该应用仅显示列表视图中的第一项' - 您是否尝试向上滚动？我问这个是因为我以前发生过很多次。
该方法应将“用户”插入数据库。无论如何，我发布了课程
【参考方案1】：
在 HomeActivity 类的 fillData 方法中，您正在使用 list.add(0,new User()) 将数据添加到 Arraylist，添加您的数据进入 0 索引，这就是你的问题的原因。您应该调用 list.add(user)
试试这个更新的代码：
public void fillData()
Cursor cursor = dbAdapter.getAllEntries();
this.listUser.clear();
if (cursor.moveToFirst())
do
long idx = cursor.getLong(cursor.getColumnIndex(DBContract.AttributiRegistrazione._ID));
String nome = cursor.getString(cursor.getColumnIndex(DBContract.AttributiRegistrazione.NOME));
String razza = cursor.getString(cursor.getColumnIndex(DBContract.AttributiRegistrazione.RAZZA));
String sesso = cursor.getString(cursor.getColumnIndex(DBContract.AttributiRegistrazione.SESSO));
User user = new User(idx, nome, razza, sesso, 10, 2000);
this.listUser.add(user);
while(cursor.moveToNext());
cursor.close();
adapter.notifyDataSetChanged();
【讨论】：
试试this solution to retrieve data from cursor 感谢您的帮助，但更新后的代码出现了与我相同的问题 你调试过你的代码吗？用户的 Arraylist 的大小是多少？ 你在 HomeActivity 类的 addNewItem 方法中做同样的事情。请改正 我不明白“在 addNewItem 方法中做同样的事情”是什么意思以上是关于数据库未从 Activity 恢复的主要内容，如果未能解决你的问题，请参考以下文章
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