http://ningtukun.blog.163.com/blog/static/186541445201310151539697/
Both the dismiss and hide methods can hide the dialog box and can be displayed with the Show method call when needed. However, there is a difference between the two.
The dismiss method frees the resources that the dialog box occupies, and the Hide method does not. You must call the dismiss method to close the dialog box before the activity exits.
If there is a ProgressBar on the dialog, you will find that after calling the dismiss method, call the Show method, the dialog box, the above ProgressBar no longer rotates, and the Hide method is called no problem.
Therefore, the most correct method of invocation is to call the dismiss method in the Ondestory method of the activity, and hide the dialog box in other places with the Hide method.
Android Development dialog Box dialog the difference between the dismiss and hide methods