避免重复收件箱的 Listview 项目

Posted 2023-04-19

【中文标题】避免重复收件箱的 Listview 项目

【英文标题】：Avoid repeating Listview items for inbox

【发布时间】：2015-07-24 08:07:59

【问题描述】：

我正在开发一个包含收件箱活动和对话活动的消息传递应用程序。为此，我使用 SQL 数据库来保存所有接收和发送的消息，并将它们附加到收件箱活动的列表视图中。我正在从数据库中获取数据以追加。我不想附加所有具有相同号码但最新消息的消息，因为其他消息正在进入对话。帮我解决这个问题。我已经搜索过了，但在这里找不到它，还有一件事，我只是一个学习者。任何意见将不胜感激！

我想要这个

收件箱活动的代码是

public class ReceiveSMSActivity extends Activity 
DBAdapter myDb;
private List<Message> MyMessages = new ArrayList<Message>();

@Override
public void onCreate(Bundle savedInstanceState) 
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    openDB();

    getResultsAndAppend();
    populateListView();


private void getResultsAndAppend() 

    Cursor cursor = myDb.getAllRows();
    if (cursor.moveToFirst()) 
        do 
            // Process the data:
            // String name = cursor.getString(DBAdapter.COL_NAME);
            String number = cursor.getString(DBAdapter.COL_NUMBER);
            String message = cursor.getString(DBAdapter.COL_MESSAGE);

            MyMessages.add(new Message(message, number, true));

         while (cursor.moveToNext());
    



private void populateListView() 

    ArrayAdapter<Message> adapter = new MyListAdapter();
    ListView list = (ListView) findViewById(R.id.listViewInbox);
    list.setAdapter(adapter);


private class MyListAdapter extends ArrayAdapter<Message> 
    public MyListAdapter() 
        super(ReceiveSMSActivity.this, R.layout.inbox_list_item_layout,
                MyMessages);
    

    @Override
    public View getView(int position, View convertView, ViewGroup parent) 
        // Make sure we have a view to work with (may have been given null)
        View itemView = convertView;
        if (itemView == null) 
            itemView = getLayoutInflater().inflate(
                    R.layout.inbox_list_item_layout, parent, false);
        

        // Find the Message to work with.
        Message currentMessage = MyMessages.get(position);

        // Message:
        TextView message = (TextView) itemView.findViewById(R.id.tvMessage);
        message.setText(currentMessage.getMessage());

        // Number:
        TextView number = (TextView) itemView.findViewById(R.id.tvNumber);
        number.setText(currentMessage.getNumber());

        return itemView;
    




@Override
protected void onDestroy() 
    super.onDestroy();
    closeDB();


private void openDB() 
    myDb = new DBAdapter(this);
    myDb.open();



private void closeDB() 
    myDb.close();

而 DBAdapter() 是

public class DBAdapter 


private static final String TAG = "DBAdapter";

// DB Fields
public static final String KEY_ROWID = "_id";
public static final int COL_ROWID = 0;


public static final String KEY_NAME = "name";
public static final String KEY_NUMBER = "number";
public static final String KEY_MESSAGE = "message";
public static final String KEY_ISSELF= "self";


public static final int COL_NAME = 1;
public static final int COL_NUMBER = 2;
public static final int COL_MESSAGE = 3;
public static final int COL_ISSELF = 4;


public static final String[] ALL_KEYS = new String[] KEY_ROWID, KEY_NAME, KEY_NUMBER, KEY_MESSAGE, KEY_ISSELF;


public static final String DATABASE_NAME = "MyDb";
public static final String DATABASE_TABLE = "mainTable";

public static final int DATABASE_VERSION = 1;   

private static final String DATABASE_CREATE_SQL = 
        "create table " + DATABASE_TABLE 
        + " (" + KEY_ROWID + " integer primary key autoincrement, "


        + KEY_NAME + " text not null, "
        + KEY_NUMBER + " string not null, "
        + KEY_MESSAGE + " string not null,"
        + KEY_ISSELF + " string not null"
        + ");";


private final Context context;

private DatabaseHelper myDBHelper;
private SQLiteDatabase db;



public DBAdapter(Context ctx) 
    this.context = ctx;
    myDBHelper = new DatabaseHelper(context);


// Open the database connection.
public DBAdapter open() 
    db = myDBHelper.getWritableDatabase();
    return this;


// Close the database connection.
public void close() 
    myDBHelper.close();


// Add a new set of values to the database.
public long insertRow(String name, String number, String message, String isself) 

    // Create row's data:
    ContentValues initialValues = new ContentValues();
    initialValues.put(KEY_NAME, name);
    initialValues.put(KEY_NUMBER, number);
    initialValues.put(KEY_MESSAGE, message);
    initialValues.put(KEY_ISSELF, isself);

    // Insert it into the database.
    return db.insert(DATABASE_TABLE, null, initialValues);


// Delete a row from the database, by rowId (primary key)
public boolean deleteRow(long rowId) 
    String where = KEY_ROWID + "=" + rowId;
    return db.delete(DATABASE_TABLE, where, null) != 0;


public void deleteAll() 
    Cursor c = getAllRows();
    long rowId = c.getColumnIndexOrThrow(KEY_ROWID);
    if (c.moveToFirst()) 
        do 
            deleteRow(c.getLong((int) rowId));              
         while (c.moveToNext());
    
    c.close();


// Return all data in the database.
public Cursor getAllRows() 
    String where = null;
    Cursor c =  db.query(true, DATABASE_TABLE, ALL_KEYS, 
                        where, null, null, null, null, null);
    if (c != null) 
        c.moveToFirst();
    
    return c;


// Get a specific row (by rowId)
public Cursor getRow(long rowId) 
    String where = KEY_ROWID + "=" + rowId;
    Cursor c =  db.query(true, DATABASE_TABLE, ALL_KEYS, 
                    where, null, null, null, null, null);
    if (c != null) 
        c.moveToFirst();
    
    return c;


// Change an existing row to be equal to new data.
public boolean updateRow(long rowId, String name, String number, String message, String isself) 
    String where = KEY_ROWID + "=" + rowId;


    // Create row's data:
    ContentValues newValues = new ContentValues();
    newValues.put(KEY_NAME, name);
    newValues.put(KEY_NUMBER, number);
    newValues.put(KEY_MESSAGE, message);
    newValues.put(KEY_ISSELF, isself);

    // Insert it into the database.
    return db.update(DATABASE_TABLE, newValues, where, null) != 0;




/////////////////////////////////////////////////////////////////////
//  Private Helper Classes:
/////////////////////////////////////////////////////////////////////

/**
 * Private class which handles database creation and upgrading.
 * Used to handle low-level database access.
 */
private static class DatabaseHelper extends SQLiteOpenHelper

    DatabaseHelper(Context context) 
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
    

    @Override
    public void onCreate(SQLiteDatabase _db) 
        _db.execSQL(DATABASE_CREATE_SQL);           
    

    @Override
    public void onUpgrade(SQLiteDatabase _db, int oldVersion, int newVersion) 
        Log.w(TAG, "Upgrading application's database from version " + oldVersion
                + " to " + newVersion + ", which will destroy all old data!");

        // Destroy old database:
        _db.execSQL("DROP TABLE IF EXISTS " + DATABASE_TABLE);

        // Recreate new database:
        onCreate(_db);
    

【参考方案1】：

一种解决方案可能是在哈希图中解析您的所有消息，该哈希图中将以电话号码作为键和模型“PeopleTexts”，该模型将包含来自同一人（号码）的消息列表，文本数量，等等。

解析后，您只需遍历哈希图而不是数据库行。

这就是逻辑。现在是一些sn-ps代码

public class PeopleTexts 

   private String phoneNumber;
   private String name;
   private ArrayList<Message> peopleTexts;

   // add setters and getters...

   public int textCount() 
      return peopleTexts.size();
   

   public void addMessage(Message message) 
      this.peopleTexts.add(message);
   

现在你只需要在你的do...while()中做事

//我的消息现在是一个 Hashmap...

if (cursor.moveToFirst()) 
    do 
         // Process the data:
         // String name = cursor.getString(DBAdapter.COL_NAME);
         String number = cursor.getString(DBAdapter.COL_NUMBER);
         String message = cursor.getString(DBAdapter.COL_MESSAGE);

        if(MyMessages.containsKey(number)) 
          MyMessages.put(number, new PeopleTexts(name, number);
        

        MyMessages.get(number).addMessage(new Message(number, message);

     while (cursor.moveToNext());

剩下的交给你。

【讨论】：

感谢 Mathieu 的回复。我使用了您的帮助并使用了 MyMessages.haskey()，但出现错误“对于 List 类型的方法 haskey(String) 未定义”我不能用这个方法。请看看这个

对不起，我是containsKey(Object key)docs.oracle.com/javase/6/docs/api/java/util/HashMap.html

它只有 contains(boolean)，我也试过了，但没有工作。仍然显示所有条目。

你在使用 Hashmap 吗？