Question

我有一个sqlite表，其数量字段的值为NUMERIC（10,5）（我知道数据类型在sqlite中意义不大）。我想写一个select语句，显示2位小数。

    id      name             type        notnull      dflt_value      pk   
------- --------------- ---------- ----------- -------------- --- 
0        _id              integer       0                            1    
1        name             varchar       1                            0    
2        amount           NUMERIC(10,5) 0                            0    

SELECT _id, name, amount FROM accounts

是否可以在select语句中转换两位小数的数量，因此我可以在应用程序中显示两位小数。我需要在select语句中格式化，不想更改表结构。提前谢谢。

我使用以下代码填充android

中的列表视图

    cursor = dbAdapter.getAccountsTotals(); 
    startManagingCursor(cursor); 
    String[] from = new String[] { DbAdapter.KEY_ID, DbAdapter.KEY_NAME, DbAdapter.KEY_AMOUNT}; 
    int[] to = new int[] { R.id.dis1, R.id.dis2, R.id.dis3}; 
    SimpleCursorAdapter trans = new SimpleCursorAdapter(this, R.layout.accts_row, cursor, from, to); 
setListAdapter(trans);

因此在从数据库中获取后无法格式化结果。请让我知道有一种方法可以在上面的代码中分配格式化值，谢谢。

Answer 1

SELECT _id, name, ROUND(amount,2) FROM accounts

以下代码会告诉您如何做到这一点

    

public class TestListView extends ListActivity {
  ...
  private DecimalFormat myCustDecFormatter = new DecimalFormat("########.00");
  ...
  ...
  /** Called when the activity is first created. */
  @Override
  public void onCreate(Bundle savedInstanceState)  {
    ...
    ...
    ...
  }

private void fillData() {
    /* Get all of the rows from the database and create the item list */
    /* for mult accts, pass in acct name? */
    mEntryCursor = mDbHelper.fetchAllEntries();
    startManagingCursor(mEntryCursor);

    // Create an array to specify the fields we want to display in the list (only TITLE)
    String[] from = new String[]{myDbAdapter.KEY_NMBR,myDbAdapter.KEY_DATE,myDbAdapter.KEY_DESCR,myDbAdapter.KEY_AMT};

    // and an array of the fields we want to bind those fields to (in this case just text1)
    int[] to = new int[]{R.id.txtnmbr, R.id.txtdate, R.id.txtdescr, R.id.txtamt};

    // Now create a simple cursor adapter and set it to display
    setListAdapter(new SimpleCursorAdapter(this, R.layout.entryrow, mEntryCursor, from, to) {
        @Override
        public void setViewText(TextView v, String text) {
          super.setViewText(v, convText(v, text));
        }

    });

  }

  private String convText(TextView v, String text) {
    switch (v.getId()) {
      case R.id.txtamt:
        double dblAmt;
        //dblAmt = Double.valueOf(text);
        dblAmt = mEntryCursor.getDouble(AMT_COLUMN);
        return myCustDecFormatter.format(dblAmt);
    }
      return text;
    } 

}//end TestListView

Answer 2

将float值保留为数据库中的浮点值，并在表示层中保留格式，如下所示：

 float f = 1.23456f;
    NumberFormat instance = NumberFormat.getInstance();
    instance.setMaximumFractionDigits(2);
    System.out.println(instance.format(f));

如何在sqlite select语句中设置2个小数位

2 个答案: