diamond-operator

Consider this Java code which attempts to instantiate some List s: List<String> list1 = new ArrayList<String>(); List<String> list2 = new ArrayList<>(); List<String> list3 = new ArrayList<String>() { }; List<String> list4 = new ArrayList<>() { }; List<String> list5 = new ArrayList<Integer>() { }; list1 and list2 are straightforward; list2 uses the new diamond operator in Java 7 to reduce unnecessary repetition of the type parameters. list3 is a variation on list1 using an anonymous class, potentially to override some methods of ArrayList . list4 attempts to use the diamond operator, similar to

I am getting this error while trying to compile some simple source code in idea ide. java: diamond operator is not supported in -source 1.6 (use -source 7 or higher to enable diamond operator) jdk is 1.7.40 from oracle but where is this place to add this "-source 7" option? i tried adding in ide settings but that had no effect. You need to set the project language level (default for all modules) and the module(s) language level Make sure that, in the Project Structure page, you have set your project language level to 7.0. After you select this, you will have to reopen your project, but then

This question already has an answer here: What is the point of the diamond operator (<>) in Java 7? 7 answers I have an arraylist with type patient_class and the arraylist type has been underlined in yellow and the IDE has mentioned "redundant type arguments in new expression (use diamond operator instead)". My problem is: Should I use the diamond operator instead? Is it a must? Will I get any data loss or any other problem when storing records to the arraylist? Here is my arraylist: public class Register_newpatient extends javax.swing.JFrame { public Register_newpatient() { initComponents();