Sqlite插入不能正常工作

Question

第一次在这里写Android应用程序。

我的用例如下：在一个活动中，我有一个TextView显示一个总结（金额总和），并且Button与EditText。这个想法是，按下按钮添加一个条目到sqlite数据库。

问题是，每当我按下按钮，看起来以前的值从输入被添加到数据库。

1. 输入10 - >按按钮 - >没有反应
2. 输入7 - >按按钮 - >摘要变化由10
3. 输入3 - >按按钮 - 由>摘要变化7 等

下面是在OnClickListener所使用的方法：

public static void addExpense(Context ctx, Expense expense) { 
     ExpensesDbHelper dbHelper = new ExpensesDbHelper(ctx); 
     SQLiteDatabase db = dbHelper.getWritableDatabase(); 


     ContentValues values = expense.toContentValues(); 
     Log.i("Daily-", "addExpense: " + values.toString()); 

     long newRowId; 
     db.beginTransaction(); 
     try { 
      newRowId = db.insert(
        ExpensesReaderContract.ExpenseEntry.TABLE_NAME, 
        null, 
        values); 

      db.setTransactionSuccessful(); 
     } finally{ 
      db.endTransaction(); 
     } 


     Log.i("Daily-", "addExpense: new id " + newRowId); 
     Cursor c = db.rawQuery("SELECT COUNT(*) from entry", null); 
     c.moveToFirst(); 
     Log.i("Daily-", "Number of rows: " + c.getInt(0)); 
     c.close(); 

     Log.i("Daily-", "addExpense: Existing " + Expense.printable(getExpenses(db))); 
    } 

这里的日志语句从输入该序列：

I/Daily-: addExpense: timestamp=2015-11-07 16:44:38 comment=Expense amount=10.0 
I/Daily-: addExpense: new id 1 
I/Daily-: Number of rows: 1 
I/Daily-: addExpense: Existing 
I/Daely-Log: 9 
I/Daily-: addExpense: timestamp=2015-11-07 16:44:41 comment=Expense amount=7.0 
I/Daily-: addExpense: new id 2 
I/Daily-: Number of rows: 2 
I/Daily-: addExpense: Existing Expense(10.000000,Expense,2015-11-07T16:44:38.000Z), 
I/Daely-Log: 9 
I/Daily-: addExpense: timestamp=2015-11-07 16:44:44 comment=Expense amount=3.0 
I/Daily-: addExpense: new id 3 
I/Daily-: Number of rows: 3 
I/Daily-: addExpense: Existing Expense(7.000000,Expense,2015-11-07T16:44:41.000Z), Expense(10.000000,Expense,2015-11-07T16:44:38.000Z), 

下面是从该活动的代码处理事件的流程：

protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_summary); 
     showAvailable(); 

     Button addExpenseButton = (Button) findViewById(R.id.add_expense); 
     final EditText amountField = (EditText) findViewById(R.id.amount); 

     addExpenseButton.setOnClickListener(new View.OnClickListener() { 
      public void onClick(View v) { 
       try { 
        float amount = Float.parseFloat(amountField.getText().toString()); 
        addExpense(amount, "Expense"); 

        showAvailable(); 
       } catch (NumberFormatException e) { 

       } 
      } 

     }); 
    } 

现在很明显，db.insert后返回，行仍然不是它应该在的地方。

我如何保证到getExpenses下次调用肯定会返回新行？

感谢您的帮助。

更新：Expense是一个非常简单的类：

public class Expense { 
    public static DateFormat iso8601Format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); 

    private float amount; 

    public float getAmount() { 
     return amount; 
    } 

    public String getComment() { 
     return comment; 
    } 

    public DateTime getTimestamp() { 
     return timestamp; 
    } 

    private String comment; 
    private DateTime timestamp; 

    public Expense(float amount, String comment, DateTime timestamp) { 
     this.amount = amount; 
     this.comment = comment; 
     this.timestamp = timestamp; 
    } 
    ... 
    public ContentValues toContentValues() { 
     ContentValues values = new ContentValues(); 
     values.put(ExpensesReaderContract.ExpenseEntry.COLUMN_NAME_AMOUNT, getAmount()); 
     values.put(ExpensesReaderContract.ExpenseEntry.COLUMN_NAME_COMMENT, getComment()); 
     values.put(ExpensesReaderContract.ExpenseEntry.COLUMN_NAME_TIMESTAMP, iso8601Format.format(getTimestamp().toDate())); 
     return values; 
    } 
} 

Answer 1

你的日志表明，插入确实确实工作 - 你得到正确的COUNT(*)了，不是吗？我会更关心Expense.printable()和getExpenses()问题，但你似乎已经切出的那部分代码，当你张贴。很可能，你在那附近的某个地方失去了一排。

如果我猜，你正在做这样的事情在你的getExpenses()方法：

if (cursor.moveToFirst()) { 
    while(cursor.moveToNext()) { 
     <stuff> 
    } 
} 

这将使你错过了第一排。如果这证明是您的问题，请跳过moveToFirst()调用，或者将循环更改为do-while。