import java.util.Arrays;  public class ArrayReverse {      public static void main(String[] args){          int[] arr ={1,2,3,4,5,6,7,8,9};          reverse(arr);      }      public static void reverse(int[] arr){          for(int i=0;i<arr.length/2;i++){              int temp = arr[i];              arr[i] =arr[arr.length-1-i];              arr[arr.length-1-i]=temp;          }          System.out.println(Arrays.toString(arr));      }  }

class  ZuiZhi   {       public static void main(String[] args)       {           int[] a={2,92,34,54,28};           minMethod(a);           maxMethod(a);       }       public static void minMethod(int[] a)       {           int min=a[0];//不能初始化为0 数组中可能有负数           for (int i=0;i<a.length;i++ )           {               if(a[i]<min)                   min=a[i];           }           System.out.println("数组内最小的元素是："+min);       }       public static void maxMethod(int[] a)       {           int max=a[0];//不能初始化为0 数组中可能有负数           for (int i=0;i<a.length;i++ )           {               if(a[i]>max)                   max=a[i];           }           System.out.println("数组内最大的元素是："+max);       }   }

/*   折半查找：   3 5 7 9 10 14   min=0 max=length-1 mid=(max+min)/2   */   class BinarySearch   {       public static void main(String[] args)       {           int[] a={3,5,7,9,10,14};           int index=binarySearch_1(a,7);           System.out.println(index);           index=binarySearch_2(a,14);           System.out.println(index);          }       public static int binarySearch_1(int[] a,int key)       {           int min=0,mid,max=a.length-1;           mid=(min+max)/2;           while (key!=a[mid])           {               if(a[mid]>key)               {                   max=mid-1;               }               else  if (a[mid]<key)               {                   min=mid+1;               }               if (max<min)                   return -1;               mid=(min+max)/2;           }           return mid;       }       public static int binarySearch_2(int[] a,int key)       {           int min=0,max=a.length-1,mid;           while (min<=max)           {               mid =(max+min)>>1;               if(a[mid]>key)               {                   max=mid-1;               }               else  if (a[mid]<key)               {                   min=mid+1;               }               else                   return mid;           }           return -1;       }   }