java - 如果从帮助程序类调用，则 Activity 方法中的 Android findViewById 不起作用

Question

我在主要 Activity 中有这个方法:

 public void setPositionToView (Context ctx, List<Address> addresses) {
       try {

    String street = addresses.get(0).getAddressLine(0);
    String city = addresses.get(0).getAddressLine(1);
    String country = addresses.get(0).getAddressLine(2);

    Log.i(AppHelper.APP_LOG_NAMESPACE, street);

    // display toast message with success state
    Toast.makeText(ctx, "TEST", Toast.LENGTH_LONG).show();

    // change state text to success and colorize text green
    TextView eanTv = (TextView) findViewById(R.id.street);
    eanTv.setText("Test");
    //stateTv.setTextColor(getResources().getColor(R.color.green));

} catch (Exception e) {
    Log.e(AppHelper.APP_LOG_NAMESPACE, "getAndSavePosition method cannot be processed", e);
    e.printStackTrace();
        }
   }

方法作为辅助类(从 Activity 扩展)的回调进行调用。

如果在方法中我尝试调用:

TextView eanTv = (TextView) findViewById(R.id.street);

我总是遇到空指针异常，但是如果我尝试像这样从 Main Activity 方法中的 onCreate 方法调用，一切都很好:

  public  void colorizeIt () {
        try {

            TextView stateTv = (TextView) findViewById(R.id.state);
            stateTv.setText("This is O.K");
        } catch (Exception e) {
            Log.e(AppHelper.APP_LOG_NAMESPACE, "getAndSavePosition method cannot be processed", e);
            e.printStackTrace();
        }
    }

我尝试为此找到一些解决方案，但没有运气，我应该创建一些布局、 View 实例或类似于下面示例的内容吗？

LayoutInflater in = getLayoutInflater() ;
    View layout = in.inflate(R.layout.toast_layout, (ViewGroup) findViewById ( R.id.toast_layout_root ) ) ;

感谢您的任何建议和示例..

Answer 1

public void setPositionToView (Context ctx, List addresses,View mainview) { try {

    String street = addresses.get(0).getAddressLine(0);
    String city = addresses.get(0).getAddressLine(1);
    String country = addresses.get(0).getAddressLine(2);

    Log.i(AppHelper.APP_LOG_NAMESPACE, street);

    // display toast message with success state
    Toast.makeText(ctx, "TEST", Toast.LENGTH_LONG).show();

    // change state text to success and colorize text green
    TextView eanTv = (TextView) mainview.findViewById(R.id.street);
    eanTv.setText("Test");
    //stateTv.setTextColor(getResources().getColor(R.color.green));

} catch (Exception e) {
    Log.e(AppHelper.APP_LOG_NAMESPACE, "getAndSavePosition method cannot be processed", e);
    e.printStackTrace();
}

}

然后像这样调用

setPositionToView (ctx, addresses,(ViewGroup)view.getParent());