Daily tip #4

When you are building a method that returns a collection, never return null. Instead, return an empty collection.

		var cars = carService.withNullOption();
		//need null test before do anything
		System.out.println("printing null option");
		if(cars != null){
            // if you don't do this you will get  
            // Cannot invoke "java.util.List.forEach(java.util.function.Consumer)" because "cars" is null
			cars.forEach(System.out::println);
		}

		cars = carService.withEmptyOption();
		System.out.println("printing empty option");
		cars.forEach(System.out::println);

		cars = carService.withValues();
		System.out.println("printing values option");
		cars.forEach(System.out::println);

Your coworkers will write less if/else, thanks to you.

Take a look in repo-tip-4 to see a real example.