如何从另一个类调用引用(TextView)findViewById

时间:2011-01-12 16:06:06

标签: android views

我创建了一个函数,用于更新我需要在多个视图上使用的数据库中的某些值。现在每个类都有自己的代码副本。基本上我读取了值,然后想要更新文本视图。

我为DisplayTop创建了一个完成工作的课程,并在本地实现了它的优秀。但不知何故,我需要通过我认为的函数发送(TextView)findViewById。我希望我这么说。那么对此的调用是什么以及如何解决(TextView)findViewById。谢谢你的帮助!

 public void DisplayTop2()
 {


  int UserID = 1;
  String D=Fun.getCurrentDateString();
  String Sql;

  Double a = 0.0;
  Double b = 0.0;

  SQLiteDatabase Db;

  String myPath = DB_PATH + DB_NAME;
  Db = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);



  Sql =" SELECT a,b " +
  " FROM test " +
  " where Dte = '" + D + "' and UserID = " + UserID;

  try {
   Cursor c = Db.rawQuery(Sql, null);

   if (c != null ) {
    if  (c.moveToFirst()) {
     do {


      a +=  (c.getDouble(c.getColumnIndex("a")));

      b +=  (c.getDouble(c.getColumnIndex("b")));

     }while (c.moveToNext());
    }
   }

   c.close();
  } catch (Exception e) {

  }
  Db.close();

  // Here is where the problem is.  The real app has 5 fields.
  // I can pass the R.id.a
  // But how do I pass the reference to findViewById to the activity that called this

  TextView tvt4 = (TextView)findViewById(R.id.a);
  D = Fun.round( a,1,BigDecimal.ROUND_HALF_UP);
  tvt4.setText( D )  ;

   tvt4 = (TextView)findViewById(R.id.b);
  D = Fun.round( b,1,BigDecimal.ROUND_HALF_UP);
  tvt4.setText( D )  ;



 };

1 个答案:

答案 0 :(得分:3)

我想我会尝试将所有UI更新保留在Activity中,而不是传递TextView个对象。为什么不创建一个Bean来填充并返回到调用活动?类似的东西:

public class Mybean {
    private String fieldA;
    private String fieldB;
    // create constructor and getters and setters here
}

然后填充并返回数据库代码中的bean。

public MyBean DisplayTop2() {
    ...
    MyBean bean = new MyBean();
    bean.setFieldA(Fun.round( a,1,BigDecimal.ROUND_HALF_UP));
    bean.setFieldB(Fun.round( b,1,BigDecimal.ROUND_HALF_UP));
    return bean;
}

然后在Activity

中填充用户界面
...
MyBean bean = MyDBClass.DisplayTop2();
TextView txtA = (TextView)findViewById(R.id.mytextviewA);
TextView txtB = (TextView)findViewById(R.id.mytextviewB);
txtA.setText(bean.getFieldA());
txtB.setText(bean.getFieldB());

这样可以将所有UI代码与数据库代码分开。