Câu hỏi phỏng vấn Java
Câu hỏi

What is difference between Array and ArrayList ? When will you use Array over ArrayList ?

Câu trả lời

Arrays and ArrayLists are both fundamental data structures in Java, but they serve different purposes and have distinct characteristics.

Difference Between Array and ArrayList

Array

  • Fixed Size: Once an array is initialized, its size cannot be altered. If you need a data structure with a fixed number of elements, an array is a suitable choice.
  • Primitive and Object Storage: Arrays can store both primitive data types (like int, char) and objects. This makes them versatile for various data handling scenarios.
  • Performance: Arrays offer fast access times because they are indexed and have a straightforward memory layout. This can be crucial in performance-sensitive applications.
  • Syntax: Arrays are accessed using the bracket syntax (e.g., array[index]), which is straightforward and familiar to most programmers.

ArrayList

  • Dynamic Size: ArrayLists can dynamically resize themselves as elements are added or removed, which provides flexibility if the number of elements is not known in advance or is expected to change.
  • Object Storage Only: ArrayLists can only store objects. Primitive data types are autoboxed to their corresponding wrapper classes (e.g., int to Integer), which can introduce additional overhead.
  • API Richness: ArrayLists come with a rich set of methods for manipulating the contents, such as add(), remove(), indexOf(), etc., making them easier to use for complex data manipulations.
  • Part of Collection Framework: ArrayList is part of Java's Collection Framework, which means it integrates well with other data structures and algorithms available in Java.

When to Use Array Over ArrayList

  1. Performance Critical Situations: If performance is a critical factor, especially when it comes to accessing elements by index, arrays might be preferable due to their simpler and faster access patterns.
  2. **Fixed Siz...
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