A question about java array

package shiyan2_2;
  import java.util.*;
  //import java.io.*;
  class info
  {
  	int num;
  	String name;
  	String sex;
  	int pnum;
  	String address;
  };
  public class Tongxun //extends info
  {	
  	//info in[];
  	int size;//记录当前元素个数
  	public void input(info in[] )
  	{
  		Scanner sc=new Scanner(System.in);
  		//System.out.println(in.length);
  		for(int i=0;i<in.length;i++)
  		{
  			in[i].num=i;
  			System.out.println("请输入姓名：");
  			in[i].name=sc.next();
  			System.out.println("请输入性别：");
  			in[i].sex=sc.next();
  			System.out.println("请输入电话：");
  			in[i].pnum=sc.nextInt();
  			System.out.println("请输入地址：");
  			in[i].address=sc.next();
  		}
  		size=in.length;	
  	}
  	public void Addarr(info in[])//新增地址
  	{
  		System.out.println("请输入您要添加的个数：");
  		int count=0;
  		Scanner sc=new Scanner(System.in);
  		count=sc.nextInt();
  		info[] newinfo=new info[in.length+count];//扩充数组
  		System.arraycopy(in,0,newinfo,0,in.length);//复制数组
  		for(int i=in.length;i<newinfo.length;i++)
  		{
  			newinfo[i].num=i;
  			System.out.println("请输入姓名：");
  			newinfo[i].name=sc.next();
  			System.out.println("请输入性别：");
  			newinfo[i].sex=sc.next();
  			System.out.println("请输入电话：");
  			newinfo[i].pnum=sc.nextInt();
  			System.out.println("请输入地址：");
  			newinfo[i].address=sc.next();
  		}
  		in=newinfo;//赋值覆盖
  		size=in.length;//更改数组长度
  		System.out.println("新增成功！！");
  	}
  	public void printall(info in[])
  	{
  		System.out.println("编号       姓名      性别        电话			通信地址 ");
  		for(int i=0;i<in.length;i++)
  		{
  			System.out.println("\t"+in[i].num+" \t"+in[i].name+"  \t"+in[i].sex+"  \t"+in[i].pnum+" \t"+in[i].address);
  		}
  	}
  			public static void main(String[] args)
  	{
  				Tongxun tx=new Tongxun();
  				System.out.println("请输入个数总数：");
  				int count=0;
  				Scanner sc=new Scanner(System.in);
  				count=sc.nextInt();
  				info in[]=new info[count];
  				tx.input(in);
  				tx.Addarr(in);
  				tx.printall(in);
  				/*while(1)
  				{
  					System.out.println("1.新增联系人");
  					System.out.println(".显示所有联系人");
  					System.out.println(".查询联系人");
  					System.out.println(".删除联系人");
  				}*/
  				
  				
  				
  	}
  			
  			
  }

run error ;
novices do not know why, I hope you answer .

Please enter the total number of :
5
Exception in thread "main" java.lang.NullPointerException
at shiyan2_2.Tongxun.input (Tongxun.java: 22)
at shiyan2_2.Tongxun.main (Tongxun.java: 74)

------ Solution ------------------------------------ --------
in [i] num = i;. / / 22 null pointer line here

info in [] = new info [count]; / / not initialized. Contents of the array is null
/ / add
for (int i = 0; i in [i] = new info ();
}
------ Solution ----------------------------------- ---------
upstairs is correct, then you generate each element of the array inside the object to be generated as an info you out this operation on the direct use of the object does not exist for its properties assignment, resulting in a null pointer exception !
------ Solution ---------------------------------------- ----
info in [] = new info [count];
info inside the array contents are not initialized
------ For reference only -------------------------- -------------
NullPointerException
This runtime exception did not know ? Breakfast is saying be friends , after it will be accompanied by your programming career
------ For reference only ----------------------- ----------------

 public void Addarr(info in[])//新增地址
      {
          System.out.println("请输入您要添加的个数：");
          int count=0;
          Scanner sc=new Scanner(System.in);
          count=sc.nextInt();
          info[] newinfo=new info[in.length+count];//扩充数组
          System.arraycopy(in,0,newinfo,0,in.length);//复制数组
          for(int i=in.length;i<newinfo.length;i++)
          {
              newinfo[i].num=i;
              System.out.println("请输入姓名：");
              newinfo[i].name=sc.next();
              System.out.println("请输入性别：");
              newinfo[i].sex=sc.next();
              System.out.println("请输入电话：");
              newinfo[i].pnum=sc.nextInt();
              System.out.println("请输入地址：");
              newinfo[i].address=sc.next();
          }
          in=newinfo;//赋值覆盖
          size=in.length;//更改数组长度
          System.out.println("新增成功！！");
      }

here can not be modified in the main , ah, how do ah ? Not add