【java基础】几个涵盖基础语法练习的小代码

1.猜数（while自建死循环，一定要配合break使用）

import java.util.Scanner;
public class GuessingDemo1 {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        int num = (int)(Math.random()*100+1);
        System.out.println("Guess it~");
        while (true){
            System.out.println("请输入要猜的数");
            int guessNum= scan.nextInt();
            if (guessNum>num){
                System.out.println("猜大了~");
            }else if (guessNum<num){
                System.out.println("猜小了~");
            }else {
                System.out.println("恭喜，猜对了~");
                break;
            }
        }
    }
}

---

2 计算票价小代码，对输入的数据进行验证

import java.util.Scanner;
public class CalAirPrice1 {
    /*
        5-10月 头等舱9 商务舱85 经济舱8
        11-4 头等舱7 商务舱65 经济舱6
     */
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        System.out.println("请输入机票原价：");
        double airPrice = scan.nextDouble();
        System.out.println("请选择月份：");
        int month = scan.nextInt();
        while (true){
            if (month>=1 && month<=12){
                break;
            }else {
                System.out.println("请输入正确月份：");
                month = scan.nextInt();
            }
        }
        System.out.println("请选择舱位：1.头等舱 2.商务舱 3.经济舱 ");
        int type = scan.nextInt();
        while (true){
            if (type>=1 && type<=3){
                break;
            }else {
                System.out.println("请输入正确舱位：");
                type = scan.nextInt();
            }
        }
        double finalPrice = calAirPrice(airPrice, month, type);
        System.out.println(finalPrice);
    }
    public static double calAirPrice(double airPrice, int month, int type){
        double finalPrice = 0.0;
        if (month>=5 && month<=10){
            switch (type){
                case 1:
                    finalPrice = airPrice * 0.9;
                    break;
                case 2:
                    finalPrice = airPrice * 0.85;
                    break;
                case 3:
                    finalPrice = airPrice * 0.80;
                    break;
            }
        }else {
            switch (type){
                case 1:
                    finalPrice = airPrice * 0.7;
                case 2:
                    finalPrice = airPrice * 0.65;
                case 3:
                    finalPrice = airPrice * 0.60;
            }
        }
        return finalPrice;
    }

}

---

3 数组求最值问题

import java.util.Arrays;
import java.util.Scanner;
/*
            6个评分1-100
           去掉最高分，和最低分后的4个评委的平均分
 */
public class CalTotalAvg1 {
    public static void main(String[] args) {
        double[] scores = enterData(6);
        //System.out.println(Arrays.toString(scores));
        double totalScore = calTotal(scores);
        //System.out.println(totalScore);
    }
    public static double[] enterData(int len){
        Scanner scan = new Scanner(System.in);
        double[] scores = new double[len];
        for (int i=0;i<scores.length;i++){
            System.out.println("请输入第"+ (i+1)+ "位评委的成绩: ");
            scores[i] = scan.nextDouble();
        }
        return scores;
    }
    public static double calTotal(double[] scores){
        double calTotal = 0.0;
        double max = scores[0];
        double min = scores[0];
        for (int i=0;i<scores.length;i++){
            if (scores[i]>max){
                max = scores[i];
            }
            if (scores[i]<min){
                min = scores[i];
            }
            calTotal += scores[i];
        }
        return calTotal - min - max;
    }
    public static double calAvg(double[] scores){
        double avg = calTotal(scores)/(scores.length-2);
        return avg;
    }
}

---

4 方法的重载（依据方法签名）

public class OverLoadDemo1 {
    public static void main(String[] args) {
        show();
        show("zhangsan");
        show("lisi",23);
        show(25,"wangwu");
    }
    public static void show(){
        System.out.println("无参数show方法...");
    }
    public static void show(String name){
        System.out.println("有参show(name)方法"+name);
    }
    public static void show(String name,int age){
        System.out.println("有参show(name+age)"+name + age);
    }
    public static void show(int age,String name){
        System.out.println("有参show(age+name)"+age+name);
    }
}

---

5 判断一个数是否是质数

import java.util.Scanner;
public class PrimeNumber1 {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        System.out.println("输入一个数判断是否是质数: ");
        int num = scan.nextInt();
        System.out.println(isPrime(num));
        //求0-n的所有质数
        printPrimes(100);
    }
    public static boolean isPrime(int num){
        boolean flag = true;
        for (int i=2;i<num/2;i++){
            if (num%i==0){
                flag = false;
                break;
            }
        }
        return flag;
    }
    public static void printPrimes(int rang){
        for (int num=2;num<rang;num++){
            boolean flag = isPrime(num);
            if (flag){
                System.out.print(num+" ");
            }
        }
    }
}

---

6 如何输入验证码

public class VeriCodeDemo1 {
    public static void main(String[] args) {
        System.out.println("输出4为验证码");
        System.out.println(veriCode(4));
    }
    public static String veriCode(int len){
        String code = "";
        char[] chs ={'a','b','c','d','e','f','g','h','i','g','k','l','m',
                'n','o','p','q','r','s','t','u','v','w','x','y','z',
                'A','B','C','D','E','F','G','H','I','J','K','L','M',
                'N','O','P','Q','R','S','T','U','V','W','X','Y','Z',
                '0','1','2','3','4','5','6','7','8','9'};
        Random ran = new Random();
        for (int i=0;i<len;i++){
            code+=chs[ran.nextInt(chs.length)];
        }
        return code;
    }
}