Java – how to test Guice singleton?

Guice singletons is strange to me

First of all, I thought

IService ser = Guice.createInjector().getInstance(IService.class);
System.out.println("ser=" + ser);
ser = Guice.createInjector().getInstance(IService.class);
System.out.println("ser=" + ser);

Will work as a single person, but it will return

ser=Service2@1975b59
ser=Service2@1f934ad

Never mind, it's not easy

Injector injector = Guice.createInjector();
IService ser = injector.getInstance(IService.class);
System.out.println("ser=" + ser);
ser = injector.getInstance(IService.class);
System.out.println("ser=" + ser);

Working as a single person

ser=Service2@1975b59
ser=Service2@1975b59

Therefore, I need to have the static field of injector (singleton for singletons)

How do I pass it to the module for testing?

Solution

When using Guice, each JVM should create only one injector Typically, you will create it at the entry point of your application (that is, in your public static void main method) If createinjector is called multiple times in the application, Guice error may be used!

Singles are examples of every syringe Note that this is not every JVM instance The best way to get singles' references is to inject it Another way is to ask for a unique syringe instance for you