java实现的选择排序、冒泡排序、二分查找，java冒泡

java实现的选择排序、冒泡排序、二分查找，java冒泡

<span >JAVA实现的冒泡排序和选择排序</span>

package com.marthevin.hhu.demo1226;
public class Demo1226 {

	/**
	 * @param args
	 */
	public static void main(String[] args) throws Exception{
		// TODO Auto-generated method stub
            Demo1226 demo = new  Demo1226();
            int[] arr = {2,54,23,22,65,3,64,22,89,235,53232,432,4533};
            //demo.bubbleSort(arr);
            demo.selectSort(arr);
            //System.out.println(demo.searchIndex(arr, 22, 0, arr.length-1));
            System.out.println(demo.halfSearch(arr, 34343));
            for(int i=0;i<arr.length;i++)
            {
            	System.out.print(arr[i]+" ");
            }
	}
	 public int getMax(int[] arr)
	 {
		int max  = arr[0];;
		for(int i=1;i<arr.length;i++)
		{
			if(max<=arr[i])
			{
				max = arr[i];
			}
			
		}
	   	return  max;
	 }
	 
	 public void bubbleSort(int[] arr)
	 {
		for(int i=0;i<arr.length-1;i++)
		{
			for(int j=0;j<arr.length-1-i;j++)
			{
				if(arr[j]>=arr[j+1])
				{
					arr[j] = arr[j]^arr[j+1];
					arr[j+1]=arr[j]^arr[j+1];
					arr[j]= arr[j+1]^arr[j];
				}
			}
		}
	 }
	 
	 public void selectSort(int[] arr )
	 {
		 for(int i=0;i<arr.length-1;i++)
		 {
			 int minIndex = i;
			 for(int j=i+1;j<arr.length;j++)
			 {
				 if(arr[j]<arr[minIndex])
				 {
					 minIndex = j;
				 }
				 
			 }
			 if(minIndex!=i)
			 {
				 //如果minIndex不等于i,交换arr[minIndex]和arr[i]即最终将最小值放在第一个位置
				 int tmp = arr[i];
				 arr[i] = arr[minIndex];
				 arr[minIndex] = tmp;
			 }
		 } 
	 }
     public int searchIndex(int[] arr,int item, int lowerIndex,int upperIndex)
     {
    	 int midIndex = (upperIndex+lowerIndex)/2;
    	 if(item==arr[midIndex])
    	 {
    		 return midIndex+1;
    	 }else if(item>arr[midIndex]){
    		 return searchIndex(arr, item,  midIndex,upperIndex);
    	 }else{
    		 return searchIndex(arr, item,  lowerIndex,midIndex);
    	 }
     }
     
     public int halfSearch(int[] arr,int item)
     {
    	 int upperIndex = arr.length-1;
    	 int lowerIndex = 0;
    	 int midIndex = (upperIndex+lowerIndex)/2;
    	 while(true)
    	 {
    		 if(item>arr[midIndex])
    		 {
    			 lowerIndex = midIndex+1;
    		 }else if(item<arr[midIndex]){
    			 upperIndex = midIndex-1;
    		 }else{
    			 return midIndex+1;
    		 }
    		 if(upperIndex<lowerIndex){
    			 return -1;
    		 }
    		 midIndex = (upperIndex+lowerIndex)/2;
    	 }
    	
     }
}