Мои вопросы для собеседования

01 сентября 2016

Как то раз пришлось вести собеседования и я решил подготовить для себя список вопросов, точнее ответов, чтобы не сесть в лужу. Вот что получилось. Заранее скажу не претендую на "правильность" вопросов, т.к. я не профессиональный собеседователь.

General

So you are going to work for us?

Spring

Will it work or not?

@Controller
class MySpringBean {
    @Autowire
    MyAnotherBean field;
}

@Controller
class MyAnotherBeanA extends MyAnotherBean {
}

@Controller
class MyAnotherBeanB extends MyAnotherBean {
}

Ways to handle exception without try-catch

@Service
class MySevice {
    @ExceptionHandler(RuntimeException.class)
    void handle() {
    }
}

@Controller
class EH implements HandlerExceptionResolver {
    resolveEx() {
    }
}

@ControllerAdvice
class GlobalEh {
    @ExeptionHandler()
    resolveEx() {
    }
}

@Controller
class EHInterceptor implements HandlerInterceptor {
}

Null view

class MyController implements Controller {
    ModelAndView handlerequest(req, res) {
        return null;
    }
}

Also ask what spring will do if we return normal ModelAndView – it will resolve view and put data to response

Java

• == VS equals
• String s1 = “a1”, s2=”a2”; s1==s2
• Object o1 = null; o2 = new SomeClass(); o1.equals(o2), o1==o2; o2=null, o1==o2//true
• Sort array
• Public MyClass {void make(){}} – what visibility level does method have without any access modifiers?
• Find max in array - O(?)
• HashMap#get – O(?) //O(1) – O(n)
• Class MyR implements Runnable {}
• (new MyR()).run() VS (new Thread(new MyR())).start()
• SPI (Service provide interface)? //loader = ServiceLoader(MyClass.class); loader.iterator()
• Stateful VS stateless

Servlet/JSP

• Servlet VS Jsp
• 1xx, 2xx, 3xx, 4xx, 5xx http codes?
• What does browser do with 302 code? //Location
• GET VS POST? Else? //PUT, DELETE

Servlet registration

<servlet>
    <servlet-name>register</servlet-name>
    <servlet-class>…</servlet-class>
</servlet>
<servlet-mapping>
    <servlet-name>register</servlet-name>
    <url-pattern>/blue/</ url-pattern>
</servlet-mapping>

Right way of catching exception in filter

class MyFilter implements Filter {
    void init() {
    }

    void doFilter(req, res, chain) throws ServletException {
        try {
            chain.doDilter(req, res)
        } catch (ServletException e) {
            throw e;
        } catch (Exception) {
            throw new ServletException(e);
        }
    }
}

Order of filters

<filterMapping/>

Forward VS Redirect

• Forward – on a server, servlet forward, same request to different URL without browser notification
• Redirect – via 302 using browser, new request is created so we cannot access to data from first request

SQL

• Find max in table column
• Joins definition (eiler circles)
• Make join //select * from Person inner join City on Person.CityId = City.Id

Html/Css

• Fixed VS absolute
• do we have these tags in html4?
• Link js only for ie? <!—[if IE]>
• Ccs hack for ie? .style{_background:#F00}
• Graceful degradation?
• Visibility:hidden VS display:none //not occupy space

JS

• ‘use strint’; x = 5; //error in ff44, chrome48, ie10
• == VS ===
• sourceMaps
• private method in JS

  (function() {
    function my() {
      alert(‘hello’);
    }
    window.myAPI = my;
  })(); //js closure
  

• Show alert with vertical scroll value

  var timeout
  function my_scroll() {
    clearTimeout(timeout)
    timeout = setTimeout(function() {
      alert(document.body.scrollTop);
    }, 500);
  }
  

• Write program with text and button on button click the text should appear
• localStorage? //setItem
• XSS/ CSRF protection way //recheck your knowledge
• Cross domain ajax call? //yes if server provide x-domain or proxy

GWT

• Access to js

  static native void method() /*-{
    $wnd.alert(‘q’);
  }-*/;
  

• EventBus
• Can we use 2 super dev mode simultaneously //-codeServerPort 9901
• Simple task to write panel, label, button and click on button
• UIBinder
• If we have a lot of data what type of widget should we use //Cell Tablem cell widget
• GWT.create(MyInterface.class) what we need to do to create interface?

JQuery

• <div class=’somename’/> //$(‘.somename’);
• <div class=’some.name’/> //$(‘.some\\.name’);
• $(selector).toogle();
• .position() VS .offset() //relative to parent, to document

Patterns

MVC

MVC is complex pattern. It consists from Observer (Model notifies View) and Strategy (View chooses Controller)

Strategy

Observer

Singleton

Complex variant:

public class Singelton {
    private static Singelton INSTANCE = null;

    public static Singelton getSingelton() {
        if (INSTANCE == null) {
            synchronized (INSTANCE) {
                if (INSTANCE == null) {
                    INSTANCE = new Singelton();
                }
            }
        }
        return INSTANCE;
    }
}