How Are Primitive Type Arrays Initialized in Java by Default?

Java: Default Array Initialization Explored

In Java, arrays of primitive types, such as int, are initialized with default values when created without explicit initialization. Let's delve into this topic.

Primitive Array Initialization

When declaring an int array without initializing it, such as int[] arr = new int[5];, Java automatically sets all elements to 0. This is because primitive types default to 0 in Java.

Default Value Verification

To demonstrate this, consider the following code snippet:

int[] arr = new int[5];
System.out.println(arr[0]); // Prints 0

The output of the above code snippet is 0, confirming that the first element of the arr array has been initialized to 0 by default.

Comparison with Explicit Initialization

To further illustrate, let's compare the default initialization with explicit initialization:

static final int UN = 0;
int[] arr = new int[5];
System.out.println(arr[0]); // Prints 0
System.out.println(arr[0] == UN); // Prints true

In this code, we compare the value of the first element in arr with the constant UN. The output will be 0 and true, indicating that the default initialization of the array has set its elements to 0, and explicitly assigning an element to 0 yields the same result.

Conclusion

In Java, primitive type arrays are automatically initialized to default values when created. For int arrays, this default value is 0. When declaring an array without explicit initialization, you can rely on this default behavior to have all elements set to 0.

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