IntelliJ IDEA “cannot resolve symbol” and “cannot resolve method”

Question

What are common causes for IntelliJ IDEA not being able to resolve built-in JVM types and methods? For example, when I mouse over String the tooltip says \"Cann

Answer 1

First check if you have configured JDK correctly:

• Go to File->Project Structure -> SDKs
• your JDK home path should be something like this: /Library/Java/JavaVirtualMachine/jdk.1.7.0_79.jdk/Contents/Home
• Hit Apply and then OK

Secondly check if you have provided in path in Library's section

• Go to File->Project Structure -> Libraries
• Hit the + button
• Add the path to your src folder
• Hit Apply and then OK

This should fix the problem