Why Do I Get a NullPointerException When Creating an Array of Custom Objects?

NullPointerException When Instantiating an Array of Custom Objects

When attempting to create an array of objects, you may encounter a NullPointerException if you do not properly initialize the individual elements of the array.

Consider the following code:

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"; // NullPointerException here
    }
}

In this example, you create an array of ResultList objects, but you have not yet created any actual objects to assign to the array elements. As a result, all elements of the boll array are initially null, and attempting to access boll[0].name will throw a NullPointerException.

To fix this exception, you must initialize the array elements before accessing their properties. This can be done by using the new keyword to create new instance of the ResultList class and assigning it to the array element, like this:

boll[0] = new ResultList();

After adding this line, you will be able to access the name and value properties of boll[0] without encountering a NullPointerException.

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