String Sorting error

[Siddhesh Desai]

import java.util.*;
import java.io.*;
class TestString
{
public static void main(String args[])
throws IOException
{
String str[]= new String[10];
//int array[]=new int[10];
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
for(int i=0;i<5;i++)
str[i]=br.readLine();
for (int i=0; i<str.length-1; i++) {
for (int j=i+1; j<str.length; j++) {
if (str[i].compareTo(str[j]) > 0) {
String temp=str[j]; str[j]=str[i]; str[i]=temp;
}
}
}
}
}
Program complies but following Run Time errors occors
Exception in thread "main" java.lang.NullPointerException
at java.lang.String.compareTo(String.java:1004)
at TestString.main(TestString.java:17)
--------------------------------------------------
please help me

[Michael Dunn]

change this
String str[]= new String[10];

to this
String str[]= new String[5];

or change this
for(int i=0;i<5;i++) str[i]=br.readLine();

to this
for(int i=0;i<10;i++) str[i]=br.readLine();