Java 中的 CopyOnWriteArrayList add()方法
原文:https://www . geeksforgeeks . org/copy onwriterarraylist-add-method-in-Java/
的 add(E e) 方法将参数中传递的元素插入到列表的末尾或列表中的指定索引处。向列表中添加新元素时，该函数返回 true。
语法:
public boolean add(E e)
or
public void add(int index, E element)
参数:该函数接受两种类型的参数，如下所述:
- Index: Specify the index of the element to be added. This parameter is not required. If this parameter is not passed, it is added at the end of the list.
- Element: Specify the element to be added in the list.
返回值:该函数在列表中添加时返回真。
以下程序说明了上述功能:
程序 1:
// Java Program to illustrate the CopyOnWriteArrayList
// add(element) method in Java
import java.util.concurrent.CopyOnWriteArrayList;
import java.util.*;
public class GFG {
public static void main(String[] args)
{
// create object of CopyOnWriteArrayList
CopyOnWriteArrayList<Integer> ArrLis
= new CopyOnWriteArrayList<Integer>();
// Add elements
ArrLis.add(2);
ArrLis.add(3);
ArrLis.add(4);
ArrLis.add(7);
// print CopyOnWriteArrayList
System.out.println("CopyOnWriteArrayList: " + ArrLis);
System.out.println("On adding 45 it returns "
+ ArrLis.add(45));
}
}
输出:
CopyOnWriteArrayList: [2, 3, 4, 7]
On adding 45 it returns true
程序二:
// Java Program to illustrate the CopyOnWriteArrayList
// add(index, element) method in Java
import java.util.concurrent.CopyOnWriteArrayList;
import java.util.*;
public class GFG {
public static void main(String[] args)
{
// create object of CopyOnWriteArrayList
CopyOnWriteArrayList<Integer> ArrLis
= new CopyOnWriteArrayList<Integer>();
// Add elements at 0th index
ArrLis.add(0, 2);
System.out.println("CopyOnWriteArrayList: " + ArrLis);
// Add elements at 0th index
ArrLis.add(0, 3);
System.out.println("CopyOnWriteArrayList: " + ArrLis);
// Add elements at 1st index
ArrLis.add(1, 4);
System.out.println("CopyOnWriteArrayList: " + ArrLis);
// Add elements at 2nd index
ArrLis.add(2, 7);
System.out.println("CopyOnWriteArrayList: " + ArrLis);
}
}
输出:
CopyOnWriteArrayList: [2]
CopyOnWriteArrayList: [3, 2]
CopyOnWriteArrayList: [3, 4, 2]
CopyOnWriteArrayList: [3, 4, 7, 2]
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