duplicate method in javap result

Question

There is a method in BaseController, e.g.

public abstract class BaseManagementController<V, F extends BaseForm> {

    @PostMapping
    @ResponseStatus(HttpStatus.CREATED)
    protected void add(@Valid @RequestBody F form, HttpServletRequest request) {
        // ...
    }
}

and a concrete Controller extends it and override add method

public class BannerController extends BaseManagementController<BannerVO, BannerForm> {
    @Override
    public void add(@Valid @RequestBody BannerForm form, HttpServletRequest request) {
        super.add(form, request);
    }
}

when I javap BannerController I see two add method

 public void add(com.foo.admin.web.vo.BannerForm, javax.servlet.http.HttpServletRequest);
    descriptor: (Lcom/foo/admin/web/vo/BannerForm;Ljavax/servlet/http/HttpServletRequest;)V
    flags: ACC_PUBLIC


  public void add(com.foo.admin.web.vo.BaseForm, javax.servlet.http.HttpServletRequest);
    descriptor: (Lcom/foo/admin/web/vo/BaseForm;Ljavax/servlet/http/HttpServletRequest;)V
    flags: ACC_PUBLIC, ACC_BRIDGE, ACC_SYNTHETIC

why have two add method? Is it overload?

Answer 1

„why have two add method?“

Because there could be some functionality that might be more generally-applicable to all Controllers. And that general functionality could be implemented in BaseManagementController.add()…

public abstract class BaseManagementController<V, F extends BaseForm> {

    @PostMapping
    @ResponseStatus(HttpStatus.CREATED)
    protected void add(@Valid @RequestBody F form, HttpServletRequest request) {
        /* ...All Controllers need to do this... */
        controlStuff(form, request);
    }

    private void controlStuff(F form, HttpServletRequest request) {
        /* ...do whatever Controllers do...*/
    }
}

Then your more specialized implementations like BannerController.add() could do something banner-related only…

public class BannerController extends BaseManagementController<BannerVO, BannerForm> {

    @Override
    public void add(@Valid @RequestBody BannerForm form, HttpServletRequest request) {
        super.add(form, request);
        processBanner(form, request);
    }

    private void processBanner(BannerForm form, HttpServletRequest request) {
        /*...do something special for banners...*/
    }
}

The subclass's add() could simply call super.add() and piggyback off of existing functionality in its super's implementation.

„Is it overload?“

No. But it is overridden…

…

An instance method mC declared in or inherited by class C overrides from C another method mA declared in class A, iff all of the following are true:

• C is a subclass of A.
• C does not inherit mA.
• The signature of m_C is a subsignature (§8.4.2) of the signature of mA.
• One of the following is true:
  • mA is public.
  • ...