What is the difference between java collection and array?

Array

Array is a built-in data type in the Java language. It is a linear sequence that can quickly access other elements and arrays. Unlike other languages, when you create an array, its capacity remains unchanged and cannot be changed during its life cycle. JAVA arrays also perform boundary checks. If an out-of-bounds phenomenon is found, a RuntimeException error will be reported. , of course checking boundaries comes at the cost of efficiency.

Collection

JAVA also provides other collections, list, map, and set. When they handle objects, it is as if these objects do not have their own types, but directly return to the roots. For Object, you only need to create a collection, put the object in it, and convert it to your own type when taking it out.

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The difference between arrays and collections

1. Array declaration The type of elements it contains, while collections are not declared.

2. The length of the array is fixed, but the length of the collection can be changed.

Arrays are static. An array instance has a fixed size. Once created, the capacity cannot be changed. Collections can dynamically expand their capacity and change their size dynamically as needed. Collections provide more member methods to meet more needs.

3. Arrays can only be stored in one type (basic type/reference type), and collections can be stored in different types (the type added when generics are not added is Object).

4. Array is a built-in data type in the Java language. It is arranged linearly and has the fastest execution efficiency or type checking.

5. Collections exist in the form of interfaces and classes. They have the characteristics of encapsulation, inheritance and polymorphism. Various complex operations can be realized through simple method and attribute calls, which greatly improves software development. efficiency.

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