Java中的 CopyOnWriteArrayList get() 方法

CopyOnWriteArrayList的get(index)方法返回指定索引处的元素。

句法：

public E get(int index)

参数：该函数接受一个强制参数索引，它指定要返回的元素的索引。

返回值：函数返回给定索引处的元素。

异常：如果索引超出范围，该函数将抛出IndexOutOfBoundsException 。

下面的程序说明了上述函数：

方案一：

// Java Program to illustrate the 
// CopyOnWriteArrayList get() 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 ArrLis
            = new CopyOnWriteArrayList();
  
        // Add elements
        ArrLis.add(32);
        ArrLis.add(67);
        ArrLis.add(98);
        ArrLis.add(100);
  
        // print CopyOnWriteArrayList
        System.out.println("CopyOnWriteArrayList: " 
                                          + ArrLis);
  
        // 2nd index in the arraylist
        System.out.println("Element at 2nd index: " 
                                    + ArrLis.get(2));
    }
}

输出：

CopyOnWriteArrayList: [32, 67, 98, 100]
Element at 2nd index: 98

方案二：

// Java Program to illustrate the 
// CopyOnWriteArrayList get() 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 ArrLis
            = new CopyOnWriteArrayList();
  
        // Add elements
        ArrLis.add("gopal");
        ArrLis.add("gfg");
        ArrLis.add("jgec");
        ArrLis.add("sudo");
  
        // print CopyOnWriteArrayList
        System.out.println("CopyOnWriteArrayList: " 
                                          + ArrLis);
  
        // 4th index element of the arraylist
        // out of range, hence error
        System.out.println("CopyOnWriteArrayList: "
                                    + ArrLis.get(4));
    }
}

输出：

Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 4
    at java.util.concurrent.CopyOnWriteArrayList.get(CopyOnWriteArrayList.java:388)
    at java.util.concurrent.CopyOnWriteArrayList.get(CopyOnWriteArrayList.java:397)
    at GFG.main(GFG.java:24)

参考： https: Java/util/concurrent/CopyOnWriteArrayList.html#get-int-