Java IntelliJ 13.1.4 "Lambda expressions are not supported at this language level."

Question

When I try to use the expression value -> value I get an error that says that Lambda is not supported. I am currently using the 1.8 JDK with Lambda support, but I still get the error. My guess is that it is IntelliJ 13.1.4 but I'm not positive.

public static void grades(){
    final List<Integer> grade = new ArrayList<Integer>();
    int gradelistnumber = 1;
    int inputedgrade = 0;

    while(inputedgrade != -1){
        System.out.println("Enter Grade for student "   gradelistnumber   " (1-50): ");
        inputedgrade = sc.nextInt();
        grade.add(inputedgrade);
        gradelistnumber  ;


    }

    System.out.println("Class Average: "   System.out.println(grade.stream().mapToInt(value -> value /*error*/).sum()));
  }

}
Solution

In addition to File > Project Structure > Project > Project Language Level as other has mention,
you should also check File > Project Structure > **Modules** > Sources > Project Language Level and set to 8