Arrays.sort() NullPointerException

[Victor Thomas]

Hello All,
I'm getting this error and really don't see where I am erring. A previous version I have runs fine in eclipse and from the commandline, however this doesn't :

import java.util.Arrays;

public class CoinDemo {
	private class nCoin{
		nCoin(){
			String s = "";
			int i = 100;
		}
	}

	public static void main(String[] args) throws CloneNotSupportedException {
		Coin p,n,d,q,h,e = null,x;CoinDemo cd;
		Coin[]cA = new Coin[9];
		p = new Coin("Penny",1);
		n = new Coin("Nickel",5);
		d = new Coin("Dime",10);
		q = new Coin("Quarter",25);
		h = new Coin("Half Dol",50);
		x = new Coin("Dollar",100);
		cA[0] = x;
		cA[2] = p;
		cA[3] = n;
		cA[4] = h;
		cA[5] = n;
		cA[6] = q;
		cA[7] = p;
		cA[8] = d;
		System.out.println(p.equals(p));
		System.out.println(p.equals(d));
		System.out.println(n.equals(new Coin("Nickel",5)));
		System.out.println(d.equals(e));	
		System.out.println(n.equals((cd = new CoinDemo()).new nCoin()));
		System.out.println(d.equals(d.clone()));
		System.out.println(d.compareTo(p));
		System.out.println(p.compareTo(d));
		System.out.println(n.compareTo((new Coin("Nickel",5))));
		System.out.println(n.compareTo((Coin)n.clone()));
		System.out.println(d.hashCode()+"="+(new Coin("Dime",10)).hashCode());
		System.out.println(cA[8]);
		Arrays.sort(cA);//craps out here....
		for(int k=0;k<cA.length;k++){
			System.out.println(cA[k]+"\t hashcode : "+cA[k].hashCode());
		}
	}
}

The class file is :

public final class Coin implements Cloneable,Comparable<Coin>{
	
	public Coin(String cN, int v){
		cName = cN;
		value = v;
	}

	private final String cName;
	private final int value;
	private volatile int hashCode = 0;
	
	public String getCName(){
		return cName;
	}
	
	public int getValue(){
		return value;
	}
	
	public boolean equals(Object obj){
		if(this == obj)return true;
		if(!(obj instanceof Coin))return false; 
		Coin c = (Coin)obj;
		return this.getCName().equals(c.getCName())
			&& this.getValue() == c.getValue();
	}
	
	public Object clone()throws CloneNotSupportedException{
		Coin c = (Coin)super.clone();
		return c;
	}
	
	public int compareTo(Coin c) {
		if(this == c) return 0;
		if(this.getCName().equals(c.getCName())
		&& this.getValue() == c.getValue()) return 0;
		return (this.getValue() < c.getValue())? -1 : 1;
	}

	public int hashCode(){
		if (hashCode == 0){
			int r = 17;
			r = 37*r + getCName().hashCode();
			r = 37*r + getValue();
			hashCode = r;
		}
		return hashCode;
	}
	
	public String toString(){
		return "nomenclature : "+getCName()+"\t value : "+getValue();
	}
}

Other than removing some comments and debugging System. out() statements, this is the same file that still works in the earlier incarnation. Any help, or quicker eyes, would be welcomed. Thanks.

V.

[Stephan van Hulst]

You get a NullPointerException because something is null that shouldn't be. It happens while sorting the array, so perhaps one of the array elements is null. Take a look at how you assign values to your array.

[Rob Camick]

cA[0] = x;   
cA[2] = p;   

Looks to me like you are missing an entry.

[Mohamed Sanaulla]

Rob Camick wrote:Looks to me like you are missing an entry.

+1.
Its throwing a NullPointer in compareTo. So the missing element might be he culprit.

[Victor Thomas]

Thanks Stephan,Rob, and Mohamed! I am embarrassed to say, I totally missed it... Apparently I need to take a break and go do some suburi. Again, thanks so much for your assistance. Take care.

V.

[Mohamed Sanaulla]

Victor Thomas wrote:Thanks Stephan,Rob, and Mohamed! I am embarrassed to say, I totally missed it... Apparently I need to take a break and go do some suburi. Again, thanks so much for your assistance. Take care.

V.

And welcome to JavaRanch!!