Returns an array containing all of the elements in this list in proper sequence (from first to last element). The returned array will be “safe” in that no references to it are maintained by this list. (In other words, this method must allocate a new array even if this list is backed...
Object[] toArray()<T> T[] toArray(T[] contents) 调用toArray() 函数会抛出“java.lang.ClassCastException”异常,但是调用 toArray(T[] contents) 能正常返回 T[]。 toArray() 会抛出异常是因为 toArray() 返回的是 Object[] 数组,将 Object[] 转换为其它类型(如如,将Object[]转换为的Integer[])...
ArrayList 类位于 java.util 包中,使用前需要引入它,语法格式如下: importjava.util.ArrayList;// 引入 ArrayList 类ArrayList<E>objectName=newArrayList<>();// 初始化 E: 泛型数据类型,用于设置 objectName 的数据类型,只能为引用数据类型。 objectName: 对象名。 ArrayList 是一个数组队列,提供了相关的添加、...
Fields inherited from class java.util.AbstractList modCount Constructor Summary Constructors Constructor and Description ArrayList() Constructs an empty list with an initial capacity of ten. ArrayList(Collection<? extendsE> c) Constructs a list containing the elements of the specified collection, in th...
Java documentation for android.os.Parcel.createInterfaceArrayList(java.util.function.Function<android.os.IBinder, T>). Portions of this page are modifications based on work created and shared by the Android Open Source Project and used according to terms described in the Creative Commons 2.5 Attribu...
import java.util.function.UnaryOperator; class MyOperator<T> implements UnaryOperator<String> { @Override public String apply(String s) { if (s == null || s.length() == 0) { return s; } return s.substring(0, 1).toUpperCase() + s.substring(1); ...
(elementData, index, elementData, index + 1, size - index); elementData[index] = element; size++; } private void rangeCheckForAdd(int index) { if (index > size || index < 0) throw new IndexOutOfBoundsException(outOfBoundsMsg(index)); } //java.lang.System /* @Function:复制数组,以...
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
You can also pass in complex types like ArrayLists of ArrayLists, hashmaps, etc. Let’s take a look at an example of using a custom class inside an ArrayList. importjava.util.ArrayList;classUser{privateStringname;privateintage;publicUser(Stringname,intage){this.name=name;this.age=age;}publ...
Java Copy In this example, we first create an empty ArrayList named ‘names’. Then, we add two names, ‘John’ and ‘Alice’, to the list using theaddmethod. Finally, we print out the list, which shows the names we added. But Java’s ArrayList initialization capabilities go far beyond...