【Java】ArrayList 的实现原理 一、概述 本例使用的是JDK8. 一上来,先来看看源码中的这一段注释,我们可以从中提取到一些关键信息: Resizable-array implementation of the List interface. Implements all optional list operations, and permits all elements, including null. In addition to implementing the List ...
Resizable-array implementation of the List interface. Implements all optional list operations, and permits all elements, includingnull. In addition to implementing the List interface, this class provides methods to manipulate the size of the array that is used internally to store the list. (This cl...
ArrayList 是java 中最常用的集合类型,这是因为它使用起来非常简单,而且它提供了非常丰富的功能,并且性能非常好,这里需要注意的是性能是以牺牲了线程安全为代价的,ArrayList 好用又很大一部分来自它的动态扩容,不像数组那样你需要提前计算好数组的大小,ArrayList 会随着元素的增加自动扩容。 虽然在其内部它并不是真正的...
2.1. With Java 9 Since Java 9, we can use aList<E>.of(E… elements)static factory method to create an immutable list: @Test(expected = UnsupportedOperationException.class)publicfinalvoidgivenUsingTheJava9_whenUnmodifiableListIsCreated_thenNotModifiable(){finalList<String> list =newArrayList<>(...
The JavaArrayListclass is part of theCollection framework. TheArrayListis an implementation of a resizable array data structure that automatically grows and shrinks when elements are added or removed in the runtime, whenever required, The new elements are always added to the end of current arraylis...
ArrayList<String>names;names.add("John");#Output:#Exceptionin thread"main"java.lang.NullPointerException Java Copy In this example, we declared an ArrayList but didn’t initialize it. When we tried to add an element to it, Java threw a ‘NullPointerException’. ...
Arraylist class implements List interface and it is based on an Array data structure. It is widely used because of the functionality and flexibility it offers. ArrayList in Java, is a resizable-array implementation of the List interface. It implements al
iterator, andlistIteratoroperations run in constant time. Theaddoperation runs inamortized constant time, that is, adding n elements requires O(n) time. All of the other operations run in linear time (roughly speaking). The constant factor is low compared to that for theLinkedListimplementation....
operations run in linear time (roughly speaking). The constant factor is low compared to that for the LinkedList implementation.* 所有其他的方法的时间复杂度都是线性的,* Each ArrayList instance has a capacity. The capacity is the size of the array used to store the elements in the list. It...
ArrayListis one of theListimplementations built atop an array, which is able to dynamically grow and shrink as you add/remove elements. Elements could be easily accessed by their indexes starting from zero. This implementation has the following properties: ...