Java Collections.reverse()用法及代码示例

java.util.Collections.reverse()方法是java.util.Collections类的方法。它颠倒了作为参数传递的列表中元素的顺序。

// Reverses elements of myList and returns Nothing.
// For example, if list contains {1, 2, 3, 4}, it converts
// list to {4, 3, 2, 1}
public static void reverse(List myList)

It throws UnsupportedOperationException if the specified 
list or its list-iterator does not support the set operation.

反转ArrayList或LinkedList。

// Java program to demonstrate working of java.utils. 
// Collections.reverse() 
import java.util.*; 
  
public class ReverseDemo 
{ 
    public static void main(String[] args) 
    { 
        // Let us create a list of strings 
        List<String>  mylist = new ArrayList<String>(); 
        mylist.add("practice"); 
        mylist.add("code"); 
        mylist.add("quiz"); 
        mylist.add("geeksforgeeks"); 
  
        System.out.println("Original List : " + mylist); 
  
        // Here we are using reverse() method 
        // to reverse the element order of mylist 
        Collections.reverse(mylist); 
  
        System.out.println("Modified List: " + mylist); 
    } 
}

输出：

Original List : [practice, code, quiz, geeksforgeeks]
Modified List: [geeksforgeeks, quiz, code, practice]

对于Linkedlist，我们只需要用“ List”中的LinkedList替换ArrayListmylist =新的ArrayList();”。

Java中的Arrays类没有反向方法。我们可以使用Collections.reverse()来反转数组。

// Java program to demonstrate reversing of array 
// with Collections.reverse() 
import java.util.*; 
  
public class ReverseDemo 
{ 
    public static void main(String[] args) 
    { 
        // Let us create an array of integers 
        Integer arr[] = {10, 20, 30, 40, 50}; 
  
        System.out.println("Original Array : " + 
                                Arrays.toString(arr)); 
          
        // Please refer below post for details of asList() 
        // https://www.geeksforgeeks.org/array-class-in-java/ 
        Collections.reverse(Arrays.asList(arr)); 
          
        System.out.println("Modified Array : " + 
                                Arrays.toString(arr)); 
    } 
}

输出：

Original Array : [10, 20, 30, 40, 50]
Modified Array : [50, 40, 30, 20, 10]

相关用法

注：本文由纯净天空筛选整理自 Collections.reverse() in Java with Examples。非经特殊声明，原始代码版权归原作者所有，本译文未经允许或授权，请勿转载或复制。