In the layout xml, add android:capitalize="sentences"
The options for android:capitalize are following :
**android:capitalize="none"** : which won't automatically capitalize anything.
**android:capitalize="sentences"** : which will capitalize the first word of each sentence.
**android:capitalize="words"** : which will capitalize the first letter of every word.
**android:capitalize="characters"** : which will capitalize every character.



**Update:**
As android:capitalize is deprecated now need to use:

**android:inputType="textCapWords"**

In the layout `xml`, add `android:capitalize="sentences"`
The options for `android:capitalize` are following :
`android:capitalize="none"` : which won't automatically capitalize anything.
`android:capitalize="sentences"` : which will capitalize the first word of each sentence.
`android:capitalize="words"` : which will capitalize the first letter of every word.
`android:capitalize="characters"` : which will capitalize every character.
Update:
As `android:capitalize` is deprecated now need to use:
android:inputType="textCapWords"