NullPointerException for String array

[ivanblackz]

I am making a PriorityQueue class for a small program, but it keeps giving(when i call on the push function) me a nullpointer exception in line 13:

else if(hi==a.length)

.
I do not understand why, It'd be great if anyone here could help me out.

public class PriorityQ
{
	private String[] a;
	private int lo,hi;
	private boolean isSort;
	
	public PriorityQ()
	{String[] a=new String[1024];lo=0;hi=0;isSort=false;}
	
	public void push(String s)
	{
		if(lo>0){a[--lo]=s;}
		else if(hi==a.length)
		{this.resize(2); a[hi]=s;}
		else
		{a[hi]=s;}
		isSort=false;
	}
...

[KevinWorkman]

In your constructor, you're declaring a new String array with the same name as the class variable String array.

That is some strange formatting, by the way. Try this to get a better idea of what you're doing:

public PriorityQ(){
   String[] a=new String[1024];
   System.out.println(a);
   System.out.println(this.a);
   lo=0;
   hi=0;
   isSort=false;
}

[ivanblackz]

I see, thank you. That means i just have to replace "String[] a=new String[1024];" with "a=new String[1024];", and now it works ^^,
This error had been troubling my mind for a while.
Thanks a lot.