Java基础面试1(基础)

Java基础面试1.面试算法练习.后端开发

0. 目录

1. Java基础面试1

1.1 基础1

1.1.1 冒泡排序

import java.util.Scanner;

//冒泡排序-Java
public class Sort{
    private static int data[]={12,10,6,7,3,16,9};

    public static void input() {
        Scanner scanner=new Scanner(System.in);
        System.out.println("请输入10个排序的数据: ");

        for(int i=1;i<data.length;i++){
            data[i]=scanner.nextInt();
        }   
    }

    public static void bubbleSort(int array[]) {
        boolean flag=false;

        for(int i=0;i<array.length-1;i++){
            flag=false;

            for(int j=array.length-1;j>i;j--){
                if(array[j-1]>array[j]){
                    int temp=array[j-1];
                    array[j-1]=array[j];
                    array[j]=temp;
                    flag=true;
                }
            }

            if(flag==false){
                return;
            }
            output();
        }
    }

    protected static void output(){
        System.out.println("顺序为:");
        for(int i=0;i<data.length;i++){
            System.out.print(data[i]+" ");
        }
        System.out.println();
    }

    public static void main(String[] args) {
        //input();
        output();
        bubbleSort(data);
        output();
    }
}

1.1.2 二分查找

public class Search {
    private static int data[]={1,2,3,4,5,6,7,8,9,10};

    //适用于有序
    public static int binarySearch(int array[],int key){
        int low=0,high=array.length-1,mid;
        while(low<=high){
            mid=(low+high)/2;
            if(array[mid]==key){
                return mid;
            }
            else if(array[mid]>key){
                high=mid-1;
            }
            else{
                low=mid+1;
            }
            System.out.println("这是一趟");
        }
        return -1;
    }

    public static void main(String[] args) {
        System.out.println(binarySearch(data, 7));
    }
}

1.1.3 时间类型转换

import java.text.ParseException;
import java.text.SimpleDateFormat;

public class DateFormat {
    private static String myDate = "20200825";

    public static void fun() {
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy 年 MM 月 dd 日");
        String newDate;
        try {
            newDate = sdf.format(new SimpleDateFormat("yyyyMMdd").parse(myDate));
            System.out.println(newDate);
        } catch (ParseException e) {
            e.printStackTrace();
        }
    }

    public static void main(String[] args) {
        fun();
    }
}

1.1.4 阶乘

public class Factorial {
    
    protected static int multiply(int num){
        if(num<0){
            System.out.println("请输入大于0的数!");
            return -1;
        }else if(num==0||num==1){
            return 1;
        }else{
            return multiply(num-1)*num;
        }
    }

    public static void main(String[] args) {
        System.out.println(multiply(10));
    }
}