copyOf(elementData, size); } public <T> T[] toArray(T[] a) { if (a.length < size)//如果传入的数组a长度小于当前列表元素个数,创建一个新数组返回 // Make a new array of a's runtime type, but my contents: return (T[]) Arrays.copyOf(elementData, size, a.getClass()); System....
returnArrays.copyOf(elementData, size); } // 返回ArrayList组成的数组 public<T> T[] toArray(T[] a) { if(a.length < size) // Make a new array of a's runtime type, but my contents: return(T[]) Arrays.copyOf(elementData, size, a.getClass()); System.arraycopy(elementData,0, a...
copyOf(elementData, size, Object[].class); } else { // 如果集合大小为空将赋值为 EMPTY_ELEMENTDATA 等同于 new ArrayList(0); this.elementData = EMPTY_ELEMENTDATA; } } 看完这个代码我最疑惑的地方是 Collection.toArray() 和 Arrays.copyOf() 这两个方法的使用,看来想明白这个构造参数具体做了什么...
publicObject[]toArray() {returnArrays.copyOf(elementData, size); } 说明: ArrayList实例转换为Array数组 源码解释: 直接调用Arrays类的copyOf (9)toArray(T[] a) public<T> T[] toArray(T[] a) {if(a.length < size)// Make a new array of a's runtime type, but my contents:return(T[]...
main(String[] args) { Person ted = new Person("Ted", "Neward", 39, new Person("Michael", "Neward", 16）， new Person("Matthew", "Neward", 10)); // Make a copy of the List List<Person> kids = new ArrayList<Person>(ted.getChildren()); // Reverse it ...
I am initially setting a employee list but want to create copy of that and then make changes to it. Even though I am creating new list its still changing the original list public class ListTest { public static void main(String[] args) { List<Employee> employeeList = new ArrayList<>()...
Returns a shallow copy of thisArrayListinstance. booleancontains(Objecto) Returnstrueif this list contains the specified element. voidensureCapacity(int minCapacity) Increases the capacity of thisArrayListinstance, if necessary, to ensure that it can hold at least the number of elements specified by ...
1 Make a transformed copy of a List using ArrayList constructor 0 Can't cast ArrayList class to ArrayList of interface 0 Java how to cast a whole List 1 Java type casting generics list of list of child to list of list of parent See more linked questions Related 27 How can I...
It will make the list empty, with zero elements in it. list.clear(); // [] 3.4. Checking ArrayList size The get the size of the arraylist, or count the number of elements in the list, we can use the size() method. ArrayList<String> list = new ArrayList<>(List.of("a", "b",...
It will make the list empty, with zero elements in it. list.clear(); // [] 3.4. Checking ArrayList size The get the size of the arraylist, or count the number of elements in the list, we can use the size() method. ArrayList<String> list = new ArrayList<>(List.of("a", "b",...