Java教程

Java Collections rotation()

Java Collections 类的 rotate()方法用于按给定的顺序旋转指定列表中的元素

语法

以下是 rotate()方法的声明:
public static void rotate(List<?> list, int distance) 

参数

参数 说明 必需/可选
list 这是要轮换的列表。 必需
distance 是要旋转列表的距离。它可以为零,负数或大于列表的大小。 必需

返回

rotate()方法不返回任何内容。

异常

UnsupportedOperationException -如果指定的列表或其列表迭代器不支持set操作,则抛出此类异常。

兼容性版本

Java 1.4及更高版本

示例1

import java.util.*;
public class CollectionsRotateExample1 {
    public static void main(String[] args) {             
        //Let us create a list of strings
            List<String>  mylist = new ArrayList<String>();
            mylist.add("Java");
            mylist.add("Python");
            mylist.add("Cobol");
            mylist.add("Perl");
            mylist.add("Android");
            System.out.println("Original List : " + mylist);  
            //Rotate the element by distance 3
            Collections.rotate(mylist, 3);  
            System.out.println("Rotated List: " + mylist);
          }
}
输出:
Original List : [Java, Python, Cobol, Perl, Android]
Rotated List: [Cobol, Perl, Android, Java, Python]

示例2

import java.util.*;
public class CollectionsRotateExample2 {
    public static void main(String[] args) {             
        //Create array list object
          List<Integer> num = new ArrayList<>();
          //Add values in the list
          for (int i = 1; i <= 10; i++) {
             num.add(i);
          }
          System.out.println("Value Before Rotation: "+Arrays.toString(num.toArray()));
          //Rotate the list at distance 5
          Collections.rotate(num, 5);
          System.out.println("Value After Rotation: "+Arrays.toString(num.toArray()));
          }
}
输出:
Value Before Rotation: [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
Value After Rotation: [6, 7, 8, 9, 10, 1, 2, 3, 4, 5]

示例3

import java.util.*;
public class CollectionsRotateExample3 {
    public static void main(String[] args) {             
        //Create an array of integers
            Integer arr[] = {10, 20, 30, 40, 50}; 
            System.out.println("Original Array: "+Arrays.toString(arr));    
            //Rotating an array by distance -2
            Collections.rotate(Arrays.asList(arr), -2);         
            System.out.println("Modified Array: "+Arrays.toString(arr));
          }
}
输出:
Original Array: [10, 20, 30, 40, 50]
Modified Array: [30, 40, 50, 10, 20]

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