Null Pointer Exception

[Corbin Blake]

Can anybody tell me how i can get rid of a null pointer exception, that happens in a runtime error.

Here are all my variables for the entire class:

public Sequence[] seqArray = new Sequence[2];
public Sequence[] aStrand = new Sequence[20];
public Sequence test= new Sequence();
public int numSeq = 0;
public int testLength = 0;
public int number =0;
public int length = 0;
public Random generator = new Random();
public String[] gene ={"A","C","G","T"};
int d = 0;

here is my code

 
public Sequence[] randomSequence(int number, int length)  
{
    Random generator = new Random();
    test.sequence = null;
    for(int i = 0; i < number; i++){// number of sequences to be made
       aStrand[i].sequence = test.sequence; //<---here is where i get the nullpointer exception
        for(int j = 0; j < length; j++){//length of sequences to be made;
          int d = generator.nextInt(4);
          aStrand[i].sequence += gene[d];     
              }
          aStrand[i].sequence += gene[d];
          }
 
    return aStrand;   
       }
 

[Mark Patrick]

What is ".sequence"?

[Joyce Lee]

Hi Corbin,

public Sequence[] aStrand = new Sequence[20];
Did you create any Sequence objects in aStrand?

For example:

  
for (int i = 0; i < aStrand.length; i++) {
    aStrand[i] = new Sequence();
}        

You might want to take a look at Java Tutorial: Arrays.

Joyce

[Corbin Blake]

okay, i have it intialized now. I swore that i have tried that before but for some reason it didn't work. Thanks so much for the help.