Eclipse doesn't mark errors immediately when editing Android project

In my memory, if I type something wrong, Eclipse will mark a error (red cross) at left hand.

But my Eclipse doesn't work so. It ma开发者_运维技巧rks errors when I press "Run as...".

I look for related setting in preference, but in vain.

This feature works well in Java projects, but not in Android projects.

Go to Window / Preferences, select General / Workspace and check Build Automatically.