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Java中数组和集合进行反转
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package com.strongant.algorithm; | |
import java.util.ArrayList; | |
import java.util.Collections; | |
import java.util.List; | |
/** | |
* 集合反转 | |
* | |
* @author <a href="mailto:strongant1994@gmail.com">strongant</a> | |
* @see | |
* @since 2017/8/20 | |
*/ | |
public class ListReverse { | |
public static void main(String[] args) { | |
int[] arr = new int[]{ | |
10, 9, 8, 7, 6, 5, 4, 3, 2, 1 | |
}; | |
List list = new ArrayList(); | |
list.add(3); | |
list.add(2); | |
list.add(1); | |
//其中jdk中自带的reverse方法内部实现使用了右移操作相关判断,比较注意的是List的set方法 | |
//该方法结构如下: E set(int index, E element) 在指定的集合索引插入某元素,然后返回该索引原始值 | |
//参考AbstractSequentialList.java 中的 set(int index, E element) 方法可知 | |
Collections.reverse(list); | |
System.out.println(list); | |
reverseArray(arr); | |
for (int i : arr) { | |
System.out.print(i); | |
System.out.print("\t"); | |
} | |
} | |
private static void reverseArray(int[] arr) { | |
for (int i = 0, len = arr.length - 1, half = arr.length >> 1; i < half; i++) { | |
int temp = arr[len - i]; | |
arr[len - i] = arr[i]; | |
arr[i] = temp; | |
} | |
} | |
} |
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