尝试显示对话框时出错
尝试显示带有时间选择器的对话框时遇到此问题，如果我使用从 getBaseContext() 返回的上下文初始化 TimePickerDialog ，而不是使用this 对当前活动的引用。 所以这段代码很好：
@Override
protected Dialog onCreateDialog( int id )
{
return new TimePickerDialog( this , mTimeSetListener, hr, min, false);
}
但是这段代码会抛出异常
protected Dialog onCreateDialog( int id )
{
return new TimePickerDialog( getBaseContext(), mTimeSetListener, hr, min, false);
}
如果我想显示一个Toast，那么我会使用
Toast.makeText( getBaseContext() , ...
它，这也有效。
我的问题是我本以为我希望对话框显示的上下文是baseContext，那么为什么Toast可以使用它，但对话框需要引用“this”，即当前的我认为它们的工作方式非常相似？
Had this problem when trying to display a Dialog with a time picker where an exception is thrown if I initialize the TimePickerDialog with the context returned from getBaseContext() as opposed to using a this reference to the current activity.
So this code is fine:
@Override
protected Dialog onCreateDialog( int id )
{
return new TimePickerDialog( this , mTimeSetListener, hr, min, false);
}
but this code throws an exception
protected Dialog onCreateDialog( int id )
{
return new TimePickerDialog( getBaseContext(), mTimeSetListener, hr, min, false);
}
If I want to display a Toast then I would use
Toast.makeText( getBaseContext() , ...
and this also works.
My question is I would have thought the context I want the Dialog to display in would be the baseContext so why does a Toast work using this but a Dialog needs a reference to "this" , i.e., the current activity as I would have thought they are both very similar in how they work?
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不要使用
getBaseContext()，除非您知道自己在做什么并且有非常具体且具体的使用原因。Toast不需要它，Dialog也不需要它。无论您使用什么Activity，都是创建Toasts和Dialogs的完美Context，所以只需使用<代码>这个。Do not use
getBaseContext()unless you know what you are doing and have a very specific and concrete reason for using it.You do not need it for a
Toast, and you do not need it for aDialog. WhateverActivityyou are using for those is a perfectly goodContextfor creatingToastsandDialogs, so just usethis.