NullPointerException when Creating an Array of objects [duplicate]

Question

I have been trying to create an array of a class containing two values, but when I try to apply a value to the array I get a NullPointerException.

public class ResultList {     public String name;     public Object value; } 

public class Test {     public static void main(String[] args){         ResultList[] boll = new ResultList[5];         boll[0].name = "iiii";     } } 

Why am I getting this exception and how can I fix it?

Answer 1

You created the array but didn't put anything in it, so you have an array that contains 5 elements, all of which are null. You could add

boll[0] = new ResultList(); 

before the line where you set boll[0].name.

Answer 2

ResultList[] boll = new ResultList[5]; 

creates an array of size=5, but does not create the array elements.

You have to instantiate each element.

for(int i=0; i< boll.length;i++)     boll[i] = new ResultList();