unable to open class file ..\..\R.java Permission denied

class 求助：我是新手，最近在照书学习时，导入的程序都在项目的图标处有个红叉， 提示：ERROR:Unable to open class file ..\..\R.java Permission denied 请问这种情况是什么导致的 ？

Help with “Error: Unable to open class file R.java” when building an Android App for the first time in Eclipse

This is just a really, quick and dirty post to help resolve this issue.

Problem:

You’ve just installed Eclipse (5.2.x at the time of this writing), and attempted to create your first Android Application. When clicking create, you see an error similar to this:

Error: Unable to open class file R.java

Solution:

The “Build Path” for your Java environment is not setup correctly in Eclipse. To fix this, follow these steps:

1) Open the Preferences Window by clicking Window -> Preferences

2) Find the Java section and expand it

3) Select Build Path

4) Change the value of Source and output folder from Folders to Project

5) Click Apply and then OK

Your problem should be resolved!