My Invalid and valid date code does not show [on hold]

I am suppose to program a code to check whether the date is valid However my issue is over here is with the output. I am unable to display out if the user has input a valid/invalid date or month. T

    String date;

   int dd,mm,yyyy;

   boolean leapyear,validdate;




   if(mm >=1 || mm <=12) // to check if user input month which is less than 1 or more than 12
   {
       System.out.println(mm+" is an invalid month");
   }
   if((mm == 4 || mm == 6 || mm == 9 || mm == 11) && (dd <= 30)) // months with 30 days
        {
            validdate = true;
            System.out.println(mm + "/" + dd + "/" + yyyy + " is a valid date.");
        }

        //For months with 31 days
       else if((mm == 1 || mm == 3 || mm== 5 || mm == 7 || mm == 8 || mm == 10 || mm == 12) && (dd <= 31))
        {
            validdate = true;
            System.out.println(mm + "/"+ dd + "/" + yyyy + " is a valid date.");

        }

    else
       {

      System.out.println("Invalid date!");

   }




  }
}

}