It's trivial to observe runtime behavior with a debugger. If you use constructor injection as it is recommended, just add a breakpoint in the constructor and s

It's trivial to observe runtime behavior with a debugger. If you use constructor injection as it is recommended, just add a breakpoint in the constructor and start the app in the debugger. @Component public class Foo { public Foo(Bar bar) { // breakpoint here } } Edit: In most cases it should be obvious what is getting injected, e.g. in the example Bar is another component/bean that was manually created. If you have two beans of the same type, use a qualifier to specify which one you want. If you are having issues with unexpected things being injected, I'd recommend setting up a few tests that establish that your app is properly wired up.