//in linear probing
public class ClosedHashing<T>
{
    T [] table;
    T tombstone;

    @SuppressWarnings("unchecked")
    public ClosedHashing(int capacity)
    {
      table = (T[]) new Object[capacity];
      tombstone=(T)new Object();
    }

    //throws IllegalStateException when full
    public void add(T x)
    {
      int pos=Math.abs(x.hashCode())%table.length;
      for(int i=0;i<table.length;i++)
      {
        int id=(pos+i)%table.length;
        if(table[id]==null || table[id]==tombstone )
        {
          table[id]=x;
          return;
        }
      }

      throw new IllegalStateException();
    }

    public T find(T x)
    {
      int pos=Math.abs(x.hashCode())%table.length;
      for(int i=0;i<table.length;i++)
      {
        int id=(pos+i)%table.length;
        if(table[id]==null) return null; //when you are lucky
        if(table[id].equals(x)) return table[id];
      }

      return null; //x is not in the table
    }

    public boolean remove(T x)
    {
      int pos=Math.abs(x.hashCode())%table.length;
      for(int i=0;i<table.length;i++)
      {
        int id=(pos+i)%table.length;
        if(table[id]==null) return false; //x is not found
        if(table[id].equals(x))
        {
          table[id]=tombstone;
          return true;
        }
      }

      return false; //x is not in the table
    }

    public void rehashing()
    {
      ClosedHashing<T> H2=new ClosedHashing<T>(table.length*2);// better to use nearest_prime(table.length*2))
      for(int i=0;i<table.length;i++)
      {
        if(table[i]!=null || table[i]==tombstone)
        {
          H2.add(table[i]);
        }
      }

      this.table=H2.table;
    }

    public static void main(String [] args)
    {
      class Record{
          int id;
          String name;

          public Record(int _id){ this.id=_id; }
          public Record(int _id, String _name){ this.id=_id; this.name=_name; }

          public int hashCode()
          {
            //return (new Integer(id)).hashCode();
            //System.out.println((new Integer(id)).hashCode());
            return (new Double(id)).hashCode();
            //return 0;
          }

          public boolean equals(Object o)
          {
            Record other=(Record)o;
            return id==other.id;
          }
      }

      SCHashing<Record> table=new SCHashing<>(13);
      table.add(new Record( 22030, "Mario"));
      table.add(new Record( 77840, "Peach"));
      table.add(new Record( 12374, "Bowser"));
      table.add(new Record( 43675, "Luigi"));
      table.add(new Record( 84146, "Toad"));

      //test
      int query=22031;
      System.out.println("ID="+query+" has name="+table.find(new Record(query)).name);
    }

}