从自定义DatePicker DialogPreference调用自定义Time DialogPreference(call custom Time DialogPreference from custom DatePicker DialogPreference)

 我需要在我的项目中实现自定义TimePicker和DatePicker DialogPreferences。 应调用第一个DatePicker对话框，然后调用TimePicker。 在本教程和本教程的帮助下，我将它们都实现到了我的项目中。 
 
 我认为我应该在onDialogClosed方法中调用TimePreference。 我这样做： 
 
    @Override
protected void onDialogClosed(boolean shouldSave) {
    if (shouldSave && this.changedValueCanBeNull != null) {
      setTheDate(this.changedValueCanBeNull);
      this.changedValueCanBeNull = null;
      Log.i("curr context", ctx.getClass().toString());
      try{

          new TimePreference(ctx,attrs).getDialog().show();
      }
      catch(Exception e)
      {
          e.printStackTrace();
      }
    }
}
 
 但是我得到一个NullPointerException。 问题是如何在DatePreference工作之后以编程方式调用我的自定义TimePreference对话框，并将这两个值都设置为DatePreference。 或者我应该创建不同的自定义ListPreference，它应该实现这两个项目？ 

I need to implement both custom TimePicker and DatePicker DialogPreferences in my project. First DatePicker Dialog should be called and then TimePicker. I implemented them both to my project with the help of this and this tutorials. 
 
I think that I should call TimePreference in the onDialogClosed method of the DatePreference. I do it like that: 
 
    @Override
protected void onDialogClosed(boolean shouldSave) {
    if (shouldSave && this.changedValueCanBeNull != null) {
      setTheDate(this.changedValueCanBeNull);
      this.changedValueCanBeNull = null;
      Log.i("curr context", ctx.getClass().toString());
      try{

          new TimePreference(ctx,attrs).getDialog().show();
      }
      catch(Exception e)
      {
          e.printStackTrace();
      }
    }
}
 
But I get an NullPointerException. Question is how can I call my custom TimePreference dialog programatically right after the DatePreference work and set both values to the DatePreference. Or I should create different custom ListPreference which should implement both of that items? 

原文：https://stackoverflow.com/questions/14984584