JAVA数组操作及选择、冒泡排序

class ArrayDemo

{

public static void main(String[] args)

{

int[] arr = {9,3,2,6,4};

//selSort(arr);

//bubSort(arr);

printArray(arr);

int max = getMax(arr);

int min = getMin(arr);

System.out.println("max="+max+";min="+min);

int index = getIndex(arr,
2);

System.out.println("2的index是："+index);

int[] ary =
{1,3,4,5,6,9};

int index1 = halfSearch1(ary,
6); //折半查找，针对有序的集合

System.out.println(index1);

}

public static int halfSearch1(int[] arr, int
key)

{

int min,max,mid;

min = 0;

max = arr.length - 1;

while (min <=
max)

{

mid = (max +
min) / 2;

if (arr[mid]
> key)

{

max
= mid - 1;

}

else if
(arr[mid] < key)

{

min
= mid + 1;

}

else

return
mid; //能找到，直接返回

}

return -1;
//循环完了还没找到，返回-1.

}

public static int halfSearch(int[] arr, int
key)

{

int min,max,mid;

min = 0;

max = arr.length - 1;

mid = (max + min) / 2;

while (arr[mid] != key)

{

if (key
> arr[mid])

{

min
= mid + 1;

}

else if (key
< arr[mid])

{

max
= mid - 1;

}

if (min
> max)

{

return
-1;

}

mid = (max +
min) / 2;

}

return
mid;

}

public static void printArray(int [] attr)

{

for(int a : attr)

{

System.out.print(a
+ ",");

}

}

public static void selSort(int[] arr)

{

for (int x=0; x
<= arr.length - 1; x++)

{

for (int y =
x+1; y <= arr.length - 1; y++)

{

if
(arr[x] > arr[y])

{

swap(arr,
x, y);

}

}

}

}

public static void bubSort(int[] arr)

{

for (int x = 0; x
<= arr.length - 1; x++)

{

for (int y =
0; y <= arr.length - 1 - x - 1; y++)

{

if
(arr[y] > arr[y+1])

{

swap(arr,
y, y + 1);

}

}

}

}

private static void swap(int[] arr, int x, int
y)

{

int tmp = arr[x];

arr[x] = arr[y];

arr[y] = tmp;

}

public static int getMax(int [] arr)

{

int max = arr[0];

for (int x = 0; x
< arr.length; x++)

{

if (arr[x]
> max)

{

max
= arr[x];

}

}

return max;

}

public static int getMin(int [] arr)

{

int min = arr[0];

for (int x = 0; x
< arr.length; x++)

{

if (arr[x]
< min)

{

min
= arr[x];

}

}

return min;

}

public static int getIndex(int [] arr, int
key)

{

for (int x = 0; x
< arr.length; x++)

{

if (arr[x] ==
key)

{

return
x;

}

}

return -1;

}

}