Programming Forums - Need array help, desperately !!

Hey there, currently i have a 1 week home/quiz some like that i quite lost on array which focuses on java OOP.

The program consist of 3 classes and 1 application to run it.

There are : Applicant , job and Agency class

i just finish doing 2 classes which is Applicant and Job class
Just the agency i not very sure how to do it. i will show below the two classes

public class Applicant{

        //attributes

        private String name;

        private String nric;

        private String qualification;

        private String field;

        private boolean available;

        

        //constructor

        public Applicant(String name, String nric, String qualification, String field, boolean available)

        {

        this.name = name;

        this.nric = nric;

        this.qualification= qualification;

        this.available= available;

        }

        

        //methods

        public String getName(){

        return name;

        }

        

        public void setAvailable(boolean a){

        available=a;

        }

        

        

        public String getNric(){

        return nric;

        }

        

        public String getQualification(){

        return qualification;

        }

        

        public String getfield(){

        return field;

        }

        

        public String toString()

        {

        String info="name: "+name+"\nnric: "+nric+"\nqualification:"+qualification+"/nfield:"+field;

        return info; 

        }

}

Job Class

    public class job{

      private String job;

      private String title;

      private String company;

      private int numofVacancy;

      private String field;

      private String qualification;

      private String id;

   

       public job(String id,String job,String title,String company,int numofVacancy, String field,String qualification) 

      {

         this.job=job;

         this.title=title;

         this.company=company;

         this.numofVacancy= numofVacancy;

         this.qualification= qualification;

         this.field=field;

         this.id=id;

      }

   

       public int computeCommission()

      {

         int commission = 0;

         if( qualification== "A level")

         {

            commission = 300;

         }

         else 

         {        

            if(qualification == "diploma")

            {

               commission = 400;

            }

            else

            {

               if(qualification == "degree or higher")

               {

                  commission = 500;

               }

            }

         }

         return commission;

      }

   

       public String getId()

      {

         return id;

      }

       public String getJob()

      {

         return job;

      }        

   

       public String getTitle()

      {

         return title;

      }

   

       public String getCompany()

      {

         return company;

      }

       public int getNumofVacancy()

      {

         return numofVacancy;

      }

       public String getField()

      {

         return field;

      }

       public String getQualification()

      {

         return qualification;

      }

       public String toString()

      {

         String info = "job:"+job+"\ntitle:"+title+"\ncompany:"+company+"\nnumber of vacancy:"+numofVacancy+"\nfield:"+field+"\nqualification"+qualification;

         return info;

      }

   

   }

Gee can some1 who good at array kindly help me with sample code to let me understand how to check on duplicate applicant, return null, add and remove array. PLease help a newbie in java.

For you guys want to know what the program wants i have put the question in document 2003 for better understanding (attachment file below)

Thanks in Advance :)