I created an Intellij project under JDK 1.6. Then I installed JDK 1.7 and removed JDK 1.6.
我在JDK 1.6下创建了一个Intellij项目。然后我安装了JDK 1.7并删除了JDK 1.6。
When I opened the project, I changed JDK to 1.7 in the Project structure dialog.
当我打开项目时，我在项目结构对话框中将JDK更改为1.7。
But my files are not recompiled - if I add errors into my code and select Build -> Rebuild project, no compiler errors appear.
但我的文件没有重新编译 - 如果我在代码中添加错误并选择Build - > Rebuild project，则不会出现编译器错误。
I also tried File -> Invalidate caches without any result.
我还尝试了File - > Invalidate caches而没有任何结果。
How can I enable compilation of my source code again?
如何再次启用源代码编译？
I'm using IntelliJ IDEA 12.1.4 Ultimate.
我正在使用IntelliJ IDEA 12.1.4 Ultimate。
Update 1 (23.09.2013 18:48 MSK): I forgot to mention that all Java files appear with a small red J near them.
更新1（2013年9月23日18:48 MSK）：我忘了提到所有Java文件都附近有一个小的红色J。
3 个解决方案
#1
3
The reason for this strange behaviour was that there was a nested Intellij project inside the one I opened. When I opened the child project, the compilation started to work.
这种奇怪行为的原因是我打开的那个内部有一个嵌套的Intellij项目。当我打开子项目时，编译开始工作。
#2
2
I had to go to Project Settings > Modules and set the Source directory so intellij would know where to look. Thank you, @maba, for that comment
我必须转到项目设置>模块并设置源目录，以便intellij知道在哪里查看。感谢@maba，感谢您的评论
#3
0
Wipe out the files in your compiler output directory (usually projectdir/out). IntelliJ only compiles changed files and the files themselves haven't changed, so you'll need to wipe out the .class files compiled under the previous JDK.
擦除编译器输出目录中的文件（通常是projectdir / out）。 IntelliJ只编译已更改的文件，文件本身没有更改，因此您需要清除在以前的JDK下编译的.class文件。
#1
3
The reason for this strange behaviour was that there was a nested Intellij project inside the one I opened. When I opened the child project, the compilation started to work.
这种奇怪行为的原因是我打开的那个内部有一个嵌套的Intellij项目。当我打开子项目时，编译开始工作。
#2
2
I had to go to Project Settings > Modules and set the Source directory so intellij would know where to look. Thank you, @maba, for that comment
我必须转到项目设置>模块并设置源目录，以便intellij知道在哪里查看。感谢@maba，感谢您的评论
#3
0
Wipe out the files in your compiler output directory (usually projectdir/out). IntelliJ only compiles changed files and the files themselves haven't changed, so you'll need to wipe out the .class files compiled under the previous JDK.
擦除编译器输出目录中的文件（通常是projectdir / out）。 IntelliJ只编译已更改的文件，文件本身没有更改，因此您需要清除在以前的JDK下编译的.class文件。