Go Project (ii), toolbar and material design style options

This is a created article in which the information may have evolved or changed.

First, the emergence of the problem:

Using Google Docs, the material design style can only be shown on Android L, the emulator with the SDK version below 21 crashes, so in order to be able to show the same effect on the lower version of the phone, we use toolbar to display it.

Two, originally used in 5.0 style of writing (in the custom theme item will have Android: the prefix of this namespace)

Third, the use of toolbar (generally in the custom theme does not have Android: this namespace prefix)

Specific detailed operation can see this blog post