Question

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]));  
}

Answer 1

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>();