Java冒泡排序与二分法查找的代码随笔

package javafirst;

import java.util.Arrays;

class MaoPao{
//升序排列
/**
* @param arr 要排序的数组
* @return int型排序好的升序数组
*/
public int[] ascendSort(int[] arr){
for(int i = 0; i < arr.length - 1; i++){
for(int k = 0; k < arr.length - 1 - i; k ++){
if (arr[k] > arr[k+1]){
int temp = arr[k];
arr[k] = arr[k+1];
arr[k+1] = temp;
}
}
}
return arr;
}
//降序排序
/**
* @param arr 需要排序的数组
* @return int型降序数组
*/
public int[] descendSort(int[] arr){
for(int i = 0; i < arr.length - 1; i++){
for(int k = 0; k < arr.length - 1 - i; k ++){
if (arr[k] < arr[k+1]){
int temp = arr[k];
arr[k] = arr[k+1];
arr[k+1] = temp;
}
}
}
return arr;
}
}
class binarySearch{
//二分法查找

/**
* @param sortArray 升序排序完的数组
* @param value 要在数组中查找的数字
* @return 返回int型索引值
*/
public int aSearch(int[] sortArray , int value){
int low = 0;
int high = sortArray.length - 1;
while(low <= high){
int middle = (low + high) / 2;
if(value > sortArray[middle]){
low = middle + 1;
}else if(value < sortArray[middle]){
high = middle - 1;
}else{
return middle;
}
}
return -1;
}
/**
* @param sortArray 降序排序完的数组
* @param value 要在数组中查找的数字
* @return 返回int型索引值
*/
public int deSearch(int[] sortArray , int value){
int low = 0;
int high = sortArray.length - 1;
while(low <= high){
int middle = (low + high) / 2;
if(value > sortArray[middle]){
high = middle - 1;
}else if(value < sortArray[middle]){
low = middle + 1;
}else{
return middle;
}
}
return -1;
}
}
public class Test12 {
public static void main(String[] args){
int[] arr1 = {10,29,8,7,9,23,29,38,27,25,34,23};
MaoPao mp = new MaoPao();
//调用其升序方法
for (int i : mp.ascendSort(arr1)){
System.out.print(i + " ");
}
System.out.println();
//调用其降序的方法
for(int i :mp.descendSort(arr1)){
System.out.print(i + " ");
}

System.out.println();

int[] arr2 = mp.ascendSort(arr1);//排序好的升序数组
binarySearch bs = new binarySearch();
System.out.println(bs.aSearch(arr2, 23));//调用的为升序二分法的查找

//因为数组是降序，所以调用二分法的降序查找方法
System.out.println(bs.deSearch(mp.descendSort(arr1), 27));
}

}

7 8 9 10 23 23 25 27 29 29 34 38
38 34 29 29 27 25 23 23 10 9 8 7
5
4