Java Arrays: When to Use `equals()` vs `Arrays.equals()`?

equals vs Arrays.equals in Java

In Java, when comparing arrays, the two statements array1.equals(array2) and Arrays.equals(array1, array2) may seem interchangeable. However, there are crucial differences between them.

array1.equals(array2)

This statement checks if the two arrays are the same object, meaning they refer to the same memory location. It returns true if and only if array1 == array2. In other words, it tests for identity, not for content equality.

Arrays.equals(array1, array2)

This statement compares the contents of the two arrays. It returns true if and only if both arrays have the same length and every corresponding element is equal.

Key Difference:

The fundamental difference between the two statements lies in their purpose. array1.equals(array2) tests for object identity, while Arrays.equals(array1, array2) tests for content equality.

When to Use Which:

• Use array1.equals(array2) when you want to check if two arrays refer to the same underlying object.
• Use Arrays.equals(array1, array2) when you want to compare the actual values contained within the arrays.

Additional Considerations:

• Be aware that array.toString() may not always provide the desired output. Arrays.toString(array) should be used to obtain a string representation of an array's contents.

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