How to call interface(instantiate) from JSNI in Google Web toolkit(GWT)

Question

I have a class which implements interface, I need to call that method from JSNI in GWT.see the below code,

interface:

public interface HeaderFormatter {
   String format(String value);
}

class:

 public GWTGrouping implements HeaderFormatter {

    public String format(String value){
      return "<span><i class='fa fa-stop'></i></span>";
    }
    public void performGrouping(){
        if(isgroup){
          grouping();
        }  
    }

    public static native void grouping() /*-{
    //dont want to pass whole class to this method (this)
    //Need to access format(String value) Method which will return some logic
    //How to access that method here by passing interface not whole class
    }-*/;

}

Answer 1

You can do it like this:

public static native void grouping(HeaderFormatter hf) /*-{
   var value = // some String 
   var result = hf.@path.to.interface.HeaderFormatter::format(Ljava/lang/String)(value);
}-*/;