Exception in thread "main" java.lang.NullPointerException ???

[Yazan]

HI ALL ..

I'm Having this problem in my program ..

The OutPut is :

(1) Open New File   (2) Open Existing File

Enter number of choice you want:2

Enter the name: N1
Exception in thread "main" java.lang.NullPointerException
    at P.search(P.java:143)
    at P.searchName(P.java:122)
    at P.<init>(P.java:24)
    at CL.main(CL.java:26)

Process completed.

When I open a new file,everyting is correct .. Just for open existing file Give me this ERROR =(

How To Solve it ??

This is the main Class :

import java.util.Scanner;
public class CL
{
	public static void main(String[] args)
	{ 
	  Scanner input=new Scanner(System.in);
	
      	 String name=null; 
         String gender=null;
         String date=null; 
         	
         System.out.print("\n(1) Open New File \t(2) Open Existing File\n\n");
         System.out.print("Enter number of choice you want:");	
         	
         int x=input.nextInt();
         if(x==1)
         {
          P obj1= new P (name,gender,date);	  
		  System.out.printf("\n\n%s\t\t%s\t\t%s\n%s\t\t\t\t%s\t\t\t%s\n\n","Patient Name: ","Gender: ","Date: ",obj1.getPatientName(),obj1.getGender(),obj1.getDate());
         } 
         	 
         if (x==2)
         {   
          System.out.print("\nEnter the name: ");
          String N = input.next();
          P obj2= new P (N);
         }
	}
}

The Second Class :

import java.util.Scanner;
public class P
{
     private String[] patientName={null,"N1",null,null,"N2",null,"N3",null,null,"N4"};
     private String[] Gender={null,"F",null,null,"M",null,"M",null,null,"F"}; 
     String name;
     String gender; 
     private int  Month;
     private int  Day;   
     private int  Year;

     
     Scanner input=new Scanner(System.in);
		        
     public P (String name , String gender, String date)
     { 
     	setPatientName(name); 
     	setGender (gender);
     	setDate(Month,Day,Year); 
     }
     
     public P (String name )
     {
     	searchName (name);
     
     }
     
     	public void setPatientName(String name)
			{  
			 int i;
		     System.out.print("\nEnter the name: ");
			 name = input.next();
		     for(i=0; i<patientName.length; i++)
				 {
				  patientName[i]=name;
                  break;
				 }	 
			}
			
		public String getPatientName ()
			{
			 int i=0;	
			 return patientName[i]; 
			}
			
			
		public void setGender ( String gender)
		 {
			int i;
			System.out.print("\nEnter the gender: ");
			gender = input.next();
            for(i=0;i<Gender.length;i++)
			 {
			  Gender[i]=gender;
              break;
			 }	 
		}
			
		public String getGender()
			{
			 int i=0;	
			 return Gender[i];
			}
			
			
		public void setDate(int month , int day ,  int year )
			{
			  
			 Month = checkMonth( month );
			 setYear (year);
			 Day = checkDay( day );			     
			}
		public String  getDate()
           {
            return String.format( "%d/%d/%d", Day , Month , Year );
           }
           	  
	  public int checkMonth( int  month )
     {
       System.out.print("\nEnter the month: ");
       month = input.nextInt();
       
        if ( month > 0 && month <= 12 ) 
           return month;
        else 
        {
         System.out.printf("Invalid month (%d) set to 1.", month );
         return 1; 
        } 
     } 
 							
     public int  checkDay( int  day )
     { 
       System.out.print("\nEnter the day: ");
       day = input.nextInt();
       
        int daysPerMonth[] = { 0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };

        if ( day > 0 && day <= daysPerMonth[ Month ] )
           return day;

        if ( Month == 2 && day == 29 && ( Year % 400 == 0 ||
             ( Year % 4 == 0 && Year % 100 != 0 ) ) )
           return day;

        System.out.printf( "Invalid day (%d) set to 1.", day );
        return  1;
     }        
     
     public void setYear (int year)
      { System.out.print("\nEnter the year: ");
        year = input.nextInt();        
        Year = year;
      }
     public int getYear()
      {
        return Year;
      }

public  void searchName(String name)
	{ 
        int result=search(name);
        
        if (result!=-1)
        { 	 
       	System.out.println("Registered Patient");
      	System.out.printf("\n\n%s\t\t%s\n%s\t\t\t\t%s\n\n","Patient Name: ","Gender: ",patientName[result],Gender[result]); 	
       	} 
     
       else
       {
       System.out.println("You are not registered"); 
     	setGender (gender);
     	setDate(Month,Day,Year);
	   System.out.printf("\n\n%s\t\t%s\t\t%s\n%s\t\t\t\t%s\t\t\t%s\n\n","Patient Name: ","Gender: ","Date: ",name,gender,getDate());
       } 
    }
         
    public  int search(String name)
    {int a=0;
     for ( int j=0; j < patientName.length; j++ )
     {
     if ( patientName[j].equals(name)  )
      a = j ; // found
     
     else  
      a = -1 ; //not found. 
     } 
    return a ; 
    }   
}

Any Help is Geatly Appreciated ..