Android - 添加到 SQLite 数据库后不会更新 ListView，除非重新启动应用程序

Posted 2023-04-19

【中文标题】Android - 添加到 SQLite 数据库后不会更新 ListView，除非重新启动应用程序

【英文标题】：Android - ListView not being updated after adding to SQLite database unless app is restarted

【发布时间】：2015-11-04 08:07:33

【问题描述】：

我目前正在尝试通过查询为适配器提供数据的 SQLite 数据库来填充 ListView，我可以通过添加条目来更新该数据库。但是，除非我重新启动应用程序，否则 ListView 不会更新。

这是我的数据源代码：

public class DataSource 

    // Database fields
    private SQLiteDatabase database;
    private SQLHelper dbHelper;
    private String[] allColumns = null;

    public DataSource(Context context) 
        dbHelper = new SQLHelper(context);
    

    public void open() throws SQLException 
        database = dbHelper.getWritableDatabase();
    

    public void close() 
        dbHelper.close();
    

    public Person addPerson(String firstname, String lastname)     
        ContentValues values = new ContentValues();
        values.put(SQLHelper.COLUMN_FIRSTNAME, firstname);
        values.put(SQLHelper.COLUMN_LASTNAME, lastname);

        long insertId = database.insert(SQLHelper.TABLE_PEOPLE, null, values);
        Cursor cursor = database.query(SQLHelper.TABLE_PEOPLE, allColumns, SQLHelper.COLUMN_ID + " = " + insertId, null, null, null, null);
        cursor.moveToFirst();
        Person newPerson = cursorToPerson(cursor);
        cursor.close();
        return newPerson;
    

    public List<Person> getAllPeople() 
        List<Person> people = new ArrayList<Person>();

        Cursor cursor = database.query(SQLHelper.TABLE_PEOPLE, allColumns, null, null, null, null, null);

        cursor.moveToFirst();
        while (!cursor.isAfterLast()) 
            Person person = cursorToPerson(cursor);
            people.add(person);
            cursor.moveToNext();
        
        cursor.close();
        return people;
    

    private Person cursorToPerson(Cursor cursor) 
        if(cursor.getCount() > 0) 
            Person person = new Person();
            person.setId(cursor.getLong(0));
            person.setFirstname(cursor.getString(1));
            person.setLastname(cursor.getString(1));
            return person;
       
       return null;
    

这里是 SQLHelper：

public class SQLHelper extends SQLiteOpenHelper 

    // Database
    private static final String DATABASE_NAME = "people.db";
    private static final int DATABASE_VERSION = 1;

    // Table
    public static final String TABLE_PEOPLE = "people";

    // Columns
    public static final String COLUMN_ID = "_id";
    public static final String COLUMN_FIRSTNAME = "first_name";
    public static final String COLUMN_LASTNAME = "last_name";

    // Database creation sql statement
    private static final String DATABASE_CREATE = "create table " + TABLE_PEOPLE + "(" + COLUMN_ID + " integer primary key autoincrement, " + COLUMN_FIRSTNAME + " text not null, " + COLUMN_LASTNAME + " text not null);";

    public SQLHelper(Context context) 
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
    

    @Override
    public void onCreate(SQLiteDatabase database) 
        database.execSQL(DATABASE_CREATE);
    

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) 
        Log.w(SQLHelper.class.getName(), "Upgrading database from version " + oldVersion + " to " + newVersion + ", which will destroy all old data"); 
        db.execSQL("DROP TABLE IF EXISTS " + TABLE_PEOPLE);
        onCreate(db);
    

为了填充我的 ListView 适配器，我调用了 getAllPeople() 方法。为了添加到我的数据库中，我调用了addPerson() 方法。 ListView 在一个对话框中。

是否有任何特殊原因我必须重新启动我的应用才能使用新人更新 ListView？

【问题讨论】：

阅读谷歌的“安卓记事本教程”，你会发现使用[Simple]CursorAdapter和自定义ContentProvider可以轻松完成

【参考方案1】：

您必须将数据更改通知您的适配器。根据适配器的类型，您需要调用swapCursor() 或notifyDatasetChanged()

【参考方案2】：

您是否在每次添加人员时都调用 notifyDataSetChanged？