up vote -2 down vote favorite

I don't know how to initialize synapseNeuronList arrayList. got null error 

private ArrayList <Integer> synapseNeuronList;
for (int j=1;j<strLine.split(" ").length-1;j++){                                              
synapseNeuronList.add(Integer.valueOf(strLine.split(" ")[j]));  
}
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1  
private ArrayList <Integer> synapseNeuronList = new ArrayList<Integer>(); ... – zeller Jul 9 '12 at 20:27
By the way, you should store the result of your split() method call in a variable. Otherwise you're calling it twice per loop, which is a big performance hit. Also, are you sure you want those conditions in your for loop and not for(int j=0;j<strs.length;j++) – Matt Jul 10 '12 at 3:40

2 Answers

up vote 4 down vote accepted

Your synapseNeuronList needs to be reference to some ArrayList (or its subtype) object. To create object use new operator like this

private ArrayList <Integer> synapseNeuronList = new ArrayList <Integer>();
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Excellent thanks – cfircoo Jul 9 '12 at 20:32
up vote 3 down vote

You would either do this directly when you declare the variable:

private ArrayList <Integer> synapseNeuronList = new ArrayList<Integer>();

or inside a constructor:

public YourClassConstructor() {
    synapseNeuronList = new ArrayList<Integer>();
}

Hope this helps!

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