Call a method before any method invocation of that class in Java -

is there way can have method in class executed every time when method of class invoked.

i'll give brief of scenario here:

class util{     private isconnected(){       if(!xxxapi.connected())             throw new myexception(....) }    public createfile(){....}    public removefile(){....} } 

so, anytime call new util.createfile() want isconnected() invoked before createfile() starts. obviously can call isconnected() everytime in starting of each method, wondering if can have solution.

is there other suggestion/solution such scenario.

you should write invocationhandler (http://docs.oracle.com/javase/7/docs/api/java/lang/reflect/invocationhandler.html) intercept calls objects, , reflectively (using reflection api) invoke first isconnected() method followed method call made.

sample: util interface:

public interface util {      void isconnected();      void createfile();      void removefile();  } 

util invocation handler:

public class utilinvocationhandler implements invocationhandler {      private util util = new utilimpl();      @override     public object invoke(object proxy, method method, object[] args)             throws throwable {          // isconnectedmethod         method isconnectedmethod = util.getclass().getmethod("isconnected");          // invoke method         isconnectedmethod.invoke(util);          // process result of above call here          // invoke method call made         object returnobj = method.invoke(util, args);          return returnobj;     }      private static class utilimpl implements util {         public void isconnected(){             system.out.println("isconnected()");         }          public void createfile(){             system.out.println("createfile()");         }          public void removefile(){             system.out.println("removefile()");         }     } } 

object initialization:

    util util = (util) proxy.newproxyinstance(                                    util.class.getclassloader(),                                     new class[] {util.class},                                     new utilinvocationhandler());