IntelliJ IDEA not show basic completion
<p>Intellij IDEA 2016.2.4 does not show basic completion.
For example:
When I typed "String", no any auto-completion pop-up, then I pressed Ctrl + Space, it said "no suggestions", as in the image below:</p>

<p><a href="https://i.stack.imgur.com/qzBUM.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/qzBUM.png" alt="IntelliJ IDEA says &quot;no suggestions&quot;"></a></p>

<p>Then I pressed Ctrl + Space 2 more times, it showed this:</p>

<p><a href="https://i.stack.imgur.com/VzNXP.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/VzNXP.png" alt="enter image description here"></a></p>

<p>Then I pressed "Enter" and it resulted in this:</p>

<p><a href="https://i.stack.imgur.com/ZIquQ.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/ZIquQ.png" alt="enter image description here"></a></p>

<p>This is happenning to all Java basic classes such as: List, Map ...</p>

<p>My questions is how to make IntelliJ IDEA generated an import statement like "<code>import java.util.List</code>" instead of using full package name like this ?</p>

<p>Thanks!</p>