Why Do I Get a NullPointerException When Creating and Using an Object Array in Java?

NullPointerException during Object Array Creation: Addressing the Issue

When attempting to work with an array of objects, you may encounter a NullPointerException. This exception occurs when you try to access an array element that hasn't been initialized yet. To understand the problem, let's analyze the provided 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";
    }
}

In this code, you define a ResultList class containing two fields: name and value. You then create an array called boll with five elements (null by default). When you try to set a value for boll[0].name, you get a NullPointerException because boll[0] is null.

To resolve this issue, you need to initialize the elements of the boll array before accessing them. You can achieve this by instantiating a new ResultList object and assigning it to each element:

public static void main(String[] args){
    ResultList[] boll = new ResultList[5];
    for (int i = 0; i < 5; i++) {
        boll[i] = new ResultList();
    }
    boll[0].name = "iiii";
}

By initializing the boll array elements, you ensure that they have valid references, avoiding the NullPointerException. Remember, when working with object arrays, it's essential to initialize their elements explicitly before using them.

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