java第四章：数组的一些排序

删除数组某个元素的普通方法

package cn.zzsxt.test.demo5;

public class TestArrayDelete {
    public static void delete(int[] arr,int element){
        int index = -1;
        System.out.println("删除前的数组为：");
        for(int i=0;i<arr.length;i++){
            System.out.print(arr[i]+"	");
            if(element ==arr[i]){
                index = i;
            }
        }
        
        for(int i=index;i<arr.length-1;i++){
            arr[i]=arr[i+1];
        }
        System.out.println();
        arr[arr.length-1]=0;
        System.out.println("删除后的数组为：");
        for(int n : arr){
            System.out.print(n+"	");
        }
    }
    public static void main(String[] args){
        int[] nums = {10,20,30,40,50};
        delete(nums,50);
        
    }
}

冒泡排序的底层实现代码

package cn.zzsxt.test.demo5;

public class TestSort {
    public static void printElement(int[] arr){
        for(int n : arr){
            System.out.print(n+"	");
        }
    }
    public static void sort(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]){
                    int temp;
                    temp=arr[j];
                    arr[j]=arr[j+1];
                    arr[j+1]=temp;
                }
            }
        }
    }
    public static void main(String[] args){
        int[] nums = {1,3,5,2,7,4,8,6,9};
        System.out.println("排序前：");
        printElement(nums);
        System.out.println("");
        sort(nums);
        System.out.println("排序后：");
        printElement(nums);
        
        
    }
}

二分法查到（折半查找）的底层实现代码

package cn.zzsxt.test.demo5;

public class TestBinarySearch {
    public static void main(String[] args){
        int[] nums = {1,2,4,5,7,8,9};
        int index = binarySearch(nums,9);
        System.out.println(index);
    }
    public static int binarySearch(int[] arr,int element){
        int left =0;
        int right = arr.length-1;
        int middle ;
        int index = -1;
        while(left<=right){
            middle = (left+right)/2;
            if(arr[middle]==element){
                index = middle;
                break;
            }else if(arr[middle]>element){
                right = middle-1;
            }else if(arr[middle]<element){
                left = middle+1;
            }
        }
        return index;
    }
}