String array problem

[shahazzat]

What is the problem of following code:

public void st(){

String[] a=null;
String a1="Hello....";

for(int i=0;i<5;i++){

a[i]=a1;
System.out.println(a[i]);
}
}

error:
Exception in thread "main" java.lang.NullPointerException

[KevinWorkman]

Your variable named a is null, so you can't dereference it. Yet you try to dereference it by using the index[] operator on it. Take a look at the tutorials to see how to initialize an array.