How Does Object Creation Work in Java Arrays?

Understanding Array Object Creation in Java

When creating an array of objects, it's important to note the difference between creating the array itself and instantiating the objects within it.

Creating an Array of References

In Java, an array of references points to the location of objects in memory, rather than storing the objects themselves. The following code creates an array of four references to objects of class A:

<code class="java">A[] arr = new A[4];</code>

Instantiating Objects Within the Array

To access the objects within the array, each reference must be assigned to an actual object. This involves creating the objects using the new keyword and assigning them to the array elements. The following code instantiates four objects of class A and assigns them to the array:

<code class="java">for (int i = 0; i < 4; i++) {
    arr[i] = new A();
}</code>

Comparison with C

In C , using new A[4] directly creates an array of four objects, whereas in Java, an additional step of assigning objects to the array references is required.

Avoiding Null Pointer Exceptions

To access methods and variables of the objects within the array, ensure that they are instantiated before attempting to use them. Failure to do so will result in null pointer exceptions.

Example

For instance, the following code snippet creates an array of two objects of class Point and sets their x and y coordinates:

<code class="java">Point[] points = new Point[2];
for (int i = 0; i < 2; i++) {
    points[i] = new Point(i, i);
}</code>

Now, the code can access the x and y coordinates of each point using the getX() and getY() methods, without encountering null pointer exceptions.

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