Before the Java project name with a red exclamation point how to solve

The reason : jdk version and already myeclipse version mismatch

Solution:

1. Select the project name -> Right -> build path -> configure buildout of the current mismatch jdk

 

 

 

 

2, and then click add library ...--> select the JRE System Library -> next -> finish

 

 

 

3, remember: Java Compiler Here, too, replaced by the corresponding version, set up is complete, you can see a red exclamation point in front of the project name not seen it