android - 试图重新打开一个已经关闭的对象 : SQLiteDatabase 1212

Question

在我的 android 应用程序中，我使用的是 sqlite 数据库，但是当使用查询从 SQLite 读取数据时，它给我错误。我想将结果放在 ListView 中。

这是我的 Activity :

public class activ5 extends Activity {
ListView etudiants=null;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activ5);
    BDD base2 = new BDD(activ5.this);
    base2.open();
    ArrayAdapter<Etudiant> etudiantAdapter = new ArrayAdapter<Etudiant>(this, android.R.layout.simple_list_item_activated_1, base2.getAllEtudiant());
    etudiants.setAdapter(etudiantAdapter);
    base2.close();

这是我数据库的代码

    private static final String CREATE_BDD_ETUDIANT = "CREATE TABLE " + TABLE_ETUDIANT + " ("
        + COL_ID_ETUDIANT + " INTEGER PRIMARY KEY AUTOINCREMENT, " + COL_NOM + " TEXT NOT NULL, "
        + COL_FILIERE + " TEXT NOT NULL, "+ COL_GROUPE +" TEXT NOT NULL);";
private static final String CREATE_BDD_PROF = "CREATE TABLE " + TABLE_PROF + " ("
        + COL_ID_PROF + " INTEGER PRIMARY KEY AUTOINCREMENT, " + COL_MODULE + " TEXT NOT NULL, "
        + COL_MATIERE +" TEXT NOT NULL);";
private static final String CREATE_BDD_ABSENCE= "CREATE TABLE " + TABLE_ABSENCE + " ("+ COL_MATIERE_ABSENCE +  " TEXT NOT NULL, "  + COL_ABSENCE + " INTEGER, "
        + COL_NOM_ABSENCE + " TEXT  REFERENCES "+TABLE_ETUDIANT+"("+COL_NOM+")); ";
private static final String CREATE_BDD_COMPTE = "CREATE TABLE " + TABLE_COMPTE + " ("+COL_ID_COMPTE+" INTEGER PRIMARY KEY AUTOINCREMENT, "
        +COL_LOGIN+" TEXT NOT NULL,"+COL_PASSWORD+" TEXT NOT NULL,"
        + COL_ID_PROF_COMPTE + " INTEGER REFERENCES "+TABLE_PROF+"("+COL_ID_PROF+"),"
        + COL_ID_ETUDIANT_COMPTE+ " INTEGER REFERENCES "+TABLE_ETUDIANT+"("+COL_ID_ETUDIANT+"));";
private MaBaseDonne(Context context) {
    super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
public static synchronized MaBaseDonne getInstance(Context context) {

    if (sInstance == null) {
        sInstance = new MaBaseDonne(context.getApplicationContext());
    }
    return sInstance;
}


@Override
public void onCreate(SQLiteDatabase db) {
    db.execSQL(CREATE_BDD_ETUDIANT);
    db.execSQL(CREATE_BDD_PROF);
    db.execSQL(CREATE_BDD_ABSENCE);
    db.execSQL(CREATE_BDD_COMPTE);
}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    db.execSQL("DROP TABLE " + TABLE_PROF + ";");
    db.execSQL("DROP TABLE " + TABLE_ETUDIANT + ";");
    db.execSQL("DROP TABLE " + TABLE_ABSENCE+ ";");
    db.execSQL("DROP TABLE " + TABLE_COMPTE+ ";");
    onCreate(db);
}

这是我得到错误的方法:

 public List<Etudiant> getAllEtudiant() {
    List<Etudiant> etudiants = new ArrayList<Etudiant>();

    Cursor cursor = bdd.query(maBaseDonne.TABLE_ETUDIANT,null, null, null, null, null, null);

    cursor.moveToFirst();
    while (!cursor.isAfterLast()) {
        Etudiant etudiant = cursorToEtudiant(cursor);
        etudiants.add(etudiant);
        cursor.moveToNext();
    }
    cursor.close();
    return etudiants;
}
public void close() {
    bdd.close();
}


 public Etudiant cursorToEtudiant(Cursor c){

    if (c.getCount() == 0)
        return null;

           c.moveToFirst();

    Etudiant etudiant = new Etudiant();

    etudiant.setId(c.getInt(NUM_COL_ID_ETUDIANT));
    etudiant.setNom(c.getString(NUM_COL_NOM));
    etudiant.setFilierere(c.getString(NUM_COL_FILIERE));
    etudiant.setGroupe(c.getString(NUM_COL_GROUPE));
    c.close();
    return etudiant;

这是日志文件:

java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.radouane.myapplication/com.example.radouane.myapplication.activ5}: java.lang.IllegalStateException: attempt to re-open an already-closed object: SQLiteQuery: SELECT * FROM table_etudiant
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2331)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2391)
        at android.app.ActivityThread.access$800(ActivityThread.java:151)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1309)
        at android.os.Handler.dispatchMessage(Handler.java:102)
        at android.os.Looper.loop(Looper.java:135)
        at android.app.ActivityThread.main(ActivityThread.java:5349)
        at java.lang.reflect.Method.invoke(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:372)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:908)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:703)
 Caused by: java.lang.IllegalStateException: attempt to re-open an already-closed object: SQLiteQuery: SELECT * FROM table_etudiant
        at android.database.sqlite.SQLiteClosable.acquireReference(SQLiteClosable.java:55)
        at android.database.sqlite.SQLiteQuery.fillWindow(SQLiteQuery.java:58)
        at android.database.sqlite.SQLiteCursor.fillWindow(SQLiteCursor.java:152)
        at android.database.sqlite.SQLiteCursor.onMove(SQLiteCursor.java:124)
        at android.database.AbstractCursor.moveToPosition(AbstractCursor.java:214)
        at android.database.AbstractCursor.moveToNext(AbstractCursor.java:245)
        at com.example.radouane.myapplication.BDD.getAllEtudiant(BDD.java:244)
        at com.example.radouane.myapplication.activ5.onCreate(activ5.java:25)
        at android.app.Activity.performCreate(Activity.java:6020)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1105)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2284)

最后是我所有方法的 DAO 类

  public SQLiteDatabase bdd;
public MaBaseDonne maBaseDonne;
String[] allColumns = {maBaseDonne.COL_NOM,maBaseDonne.COL_GROUPE};

public BDD(Context context) {

    maBaseDonne = MaBaseDonne.getInstance(context.getApplicationContext());
}

public void open(){
    bdd = maBaseDonne.getWritableDatabase();
}
public void read()
{
    bdd=maBaseDonne.getReadableDatabase();   }


public SQLiteDatabase getBDD(){
    return bdd;
}

public long insertEtudiant(Etudiant etudiant) {
    ContentValues values = new ContentValues();

    values.put(COL_NOM, etudiant.getNom());
    values.put(COL_FILIERE, etudiant.getFiliere());
    values.put(COL_GROUPE, etudiant.getGroupe());
    return bdd.insert(TABLE_ETUDIANT, null, values);
}
public long insertProf(Prof prof) {
    ContentValues values = new ContentValues();
    values.put(COL_MODULE, prof.getModule());
    values.put(COL_MATIERE, prof.getMatiere());
    return bdd.insert(TABLE_PROF, null, values);
}
public long insertAbsence(Absence absence) {
    ContentValues values = new ContentValues();
    values.put(COL_NOM_ABSENCE, absence.getNom());
    values.put(COL_MATIERE, absence.getMatiere());
    values.put(COL_ABSENCE, absence.getAbsence());
    return bdd.insert(TABLE_ABSENCE, null, values);
}
public long insertCompte(Compte compte) {
    ContentValues values = new ContentValues();
    values.put(COL_LOGIN, compte.getLogin());
    values.put(COL_PASSWORD, compte.getPassword());
    values.put(COL_ID_PROF_COMPTE, compte.getId_prof());
    values.put(COL_ID_ETUDIANT_COMPTE, compte.getId_etudiant());

    return bdd.insert(TABLE_COMPTE, null, values);
}
public int updateEtudiant(int id, Etudiant etudiant) {

    ContentValues values = new ContentValues();
    values.put(COL_ID_ETUDIANT, etudiant.getId());
    values.put(COL_NOM, etudiant.getNom());
    values.put(COL_FILIERE, etudiant.getFiliere());
    values.put(COL_GROUPE, etudiant.getGroupe());
    return bdd.update(TABLE_ETUDIANT, values, COL_ID_ETUDIANT + " = " + id, null);
}
public int updateProf(int id, Prof prof) {

    ContentValues values = new ContentValues();
    values.put(COL_ID_PROF, prof.getId());
    values.put(COL_MODULE, prof.getModule());
    values.put(COL_MATIERE, prof.getMatiere());
    return bdd.update(TABLE_ETUDIANT, values, COL_ID_PROF + " = " + id, null);
}
public int updateAbsence(String nom_eleve, Absence absence) {

    ContentValues values = new ContentValues();
    values.put(COL_NOM_ABSENCE, absence.getNom());
    values.put(COL_MATIERE, absence.getMatiere());
    values.put(COL_ABSENCE, absence.getAbsence());
    return bdd.update(TABLE_ETUDIANT, values, COL_NOM_ABSENCE + " = " + nom_eleve, null);
}
public int updateCompte(String login, Compte compte) {

    ContentValues values = new ContentValues();
    values.put(COL_LOGIN, compte.getLogin());
    values.put(COL_PASSWORD, compte.getPassword());
    values.put(COL_ID_PROF_COMPTE, compte.getId_prof());
    values.put(COL_ID_ETUDIANT_COMPTE, compte.getId_etudiant());
    return bdd.update(TABLE_COMPTE, values, COL_LOGIN + " = " + login, null);
}
  public int removeEtudiant(int id){
    return bdd.delete(TABLE_ETUDIANT, COL_ID_ETUDIANT + " = " + id, null);
}
public int removeProf(int id){
    return bdd.delete(TABLE_PROF, COL_ID_PROF + " = " +id, null);
}
public int removeAbsence(String nom_eleve){
    return bdd.delete(TABLE_ABSENCE, COL_NOM_ABSENCE + " = " +nom_eleve, null);
}
public int removeCompte(String login){
    return bdd.delete(TABLE_COMPTE, COL_LOGIN + " = " + login, null);
}

public Etudiant getEtudiant(int id){
    Cursor c = bdd.query(TABLE_ETUDIANT, new String[] {COL_ID_ETUDIANT, COL_NOM, COL_FILIERE,COL_GROUPE}, COL_ID_ETUDIANT + " LIKE \"" + id +"\"", null, null, null, null);
    return cursorToEtudiant(c);
}
public Prof getProf(int id){
    Cursor c = bdd.query(TABLE_PROF, new String[] {COL_ID_PROF, COL_MODULE, COL_MATIERE}, COL_ID_PROF + " LIKE \"" + id +"\"", null, null, null, null);
    return cursorToProf(c);
}
public Absence getAbsence(String nom_eleve){
    Cursor c = bdd.query(TABLE_ABSENCE, new String[] {COL_NOM_ABSENCE, COL_MATIERE_ABSENCE, COL_ABSENCE}, COL_NOM_ABSENCE + " LIKE \"" + nom_eleve +"\"", null, null, null, null);
    return cursorToAbsence(c);
}
public Compte getCompte(String login,String password){
    Cursor c = bdd.query(TABLE_COMPTE, new String[] {COL_LOGIN, COL_PASSWORD, COL_ID_PROF_COMPTE,COL_ID_ETUDIANT_COMPTE},COL_LOGIN + " LIKE \"" + login +"\""+" and "+COL_LOGIN + " LIKE \"" + login +"\"" , null, null, null, null);
    return cursorToCompte(c);
}

public Etudiant cursorToEtudiant(Cursor c){

    if (c.getCount() == 0)
        return null;

           c.moveToFirst();

    Etudiant etudiant = new Etudiant();

    etudiant.setId(c.getInt(NUM_COL_ID_ETUDIANT));
    etudiant.setNom(c.getString(NUM_COL_NOM));
    etudiant.setFilierere(c.getString(NUM_COL_FILIERE));
    etudiant.setGroupe(c.getString(NUM_COL_GROUPE));
    c.close();
    return etudiant;
}
private Prof cursorToProf(Cursor c) {

    if (c.getCount() == 0)
        return null;


    c.moveToFirst();

    Prof prof = new Prof();

    prof.setId(c.getInt(NUM_COL_ID_ETUDIANT));
    prof.setModule(c.getString(NUM_COL_MODULE));
    prof.setMatiere(c.getString(NUM_COL_MATIERE));
    c.close();
    return prof;
}
private Absence cursorToAbsence(Cursor c) {

    if (c.getCount() == 0)
        return null;


    c.moveToFirst();

    Absence absence = new Absence();

    absence.setNom(c.getString(NUM_COL_NOM_ABSENCE));
    absence.setMatiere(c.getString(NUM_COL_MATIERE));
    absence.setAbsence(c.getInt(NUM_COL_ABSENCE));
    c.close();
    return absence;
}

private Compte cursorToCompte(Cursor c) {

    if (c.getCount() == 0)
        return null;


    c.moveToFirst();

    Compte compte = new Compte();

    compte.setLogin(c.getString(NUM_COL_LOGIN));
    compte.setPassword(c.getString(NUM_COL_PASSWORD));
    compte.setId_prof(c.getInt(NUM_COL_ID_PROF_COMPTE));
    compte.setId_etudiant(c.getInt(NUM_COL_ID_ETUDIANT_COMPTE));
    return compte;
}
public List<Etudiant> getAllEtudiant() {
    List<Etudiant> etudiants = new ArrayList<Etudiant>();

    Cursor cursor = bdd.query(maBaseDonne.TABLE_ETUDIANT,null, null, null, null, null, null);

    cursor.moveToFirst();
    while (!cursor.isAfterLast()) {
        Etudiant etudiant = cursorToEtudiant(cursor);
        etudiants.add(etudiant);
        cursor.moveToNext();
    }
    cursor.close();
    return etudiants;
}
public void close() {
    bdd.close();
}

我已经卡了一整天了，欢迎任何帮助，谢谢你``

Answer 1

在 getAllEtudiant() 中，您正在调用 cursorToEtudiant(cursor);，在此方法中，您正在关闭光标 c.close();，因此下一次在循环中关闭游标，只需删除 c.close()，因为您在 getAllEtudiant() 中的 while 循环之后关闭了游标