java基础案例

java案例

买飞机票

package com.item.huang;
//买飞机票

public class Test01 {
    public static void main(String[] args) {
        double price = calculate(1000,5,"经济舱");
        System.out.println(price);
    }
    //方法头需接收机票原价，当前月份，舱位类型
    //方法头需返回计算出的机票优惠价
    public static double calculate(double price,int month,String type){
        //方法体
        //1.判断当前月份是淡季还是旺季（通过判断数据在哪个区间，来决定执行哪个业务，应用if分支结构实现）
        //2.判断舱位类型（通过判断数据匹配哪个值，来决定执行哪个业务，应用switch分支结构实现）
        if (month>=5 && month<=10){
            switch (type) {
                case "头等舱":
                    price *= 0.9;
                    break;
                case "经济舱":
                    price *= 0.85;
            }
            }else{
            switch (type) {
                case "头等舱":
                    price *= 0.7;
                    break;
                case  "经济舱":
                    price *= 0.65;
                    break;
            }
            }
        return price;
    }

}

开发验证码

package com.item.huang;

import java.util.Random;

//开发验证码
public class Test02 {
    public static void main(String[] args) {
        String code = createCode(5);
        System.out.println(code);
    }
    //方法名
    //1.接收验证码的位数
    //2.返回验证码
    public static String createCode(int number){
        //方法体
        //1.使用Random类产生随机数，定义字符串code以便返回验证码
        //2.使用switch分支结构判断随机数，从而随机一个数字（0-9），大写字母还是小写字母
        //3.使用"+"运算符，连接字符
        String code = "";
        Random r = new Random();
        for (int i = 0; i < number; i++) {
        int type = r.nextInt(3);
        switch (type){
            case 0:
                //随机一个数字
                code += r.nextInt(10);
                break;
            case 1:
                //随机一个大写字母
                code += (char)(r.nextInt(26)+65);
                break;
            case 2:
                //随机一个小写字母
                code += (char)(r.nextInt(26)+97);
                break;
        }
        }
        return code;
    }

}

评委打分

package com.item.huang;

import java.util.Scanner;

//评委打分
public class Test03 {
    public static void main(String[] args) {
        System.out.println("该选手分数是"+getAverageScore(6));
    }
    public static double getAverageScore(int number){
        //动态创建数组，存储评委打分
        int[] scores = new int[number];
        //遍历数组，输入评委打分,同时增加可读性
        Scanner sc = new Scanner(System.in);
        for (int i = 0; i < scores.length; i++) {
            System.out.println("请输入第"+(i+1)+"个评委的分数：");
            sc.hasNextInt();
            int score = sc.nextInt();
            scores[i] = score;
        }
        //减掉最高分和最低分，再求平均分，返回最终的分数
        int sum = 0;
        int max = scores[0];
        int min = scores[0];
        for (int i = 0; i < scores.length; i++) {
            //计算总分
            sum += scores[i];
            //计算最高分
            if (scores[i]>max){
                max = scores[i];
            }
            //计算最低分
            if (scores[i]<min){
                min = scores[i];
            }
        }
        //返回最终的分数
        return 1.0*(sum-max-min)/(number-2);

    }
}

数字加密

package com.item.huang;

import java.util.Scanner;

//数字加密
public class Test04 {
    public static void main(String[] args) {
        System.out.println("加密后的密码是："+enCrypt(1983));
    }

    public static String enCrypt(int number){
        int[] numbers = split(number);
        //numbers[1,9,8,3]
        for (int i = 0; i < numbers.length; i++) {
            numbers[i] = (numbers[i]+5)%10;
        }
        //numbers[6,4,3,8]
        reverse(numbers);
        //numbers[8,3,4,6]
        String data = "";
        for (int i = 0; i < numbers.length; i++) {
            data += numbers[i];
        }
        //data = "8346"
        return data;
    }
    public static int[] split(int number){
        //number 1983
        int[] numbers = new int[4];
        numbers[0] = number/10/10/10%10;
        numbers[1] = number/10/10%10;
        numbers[2] = number/10%10;
        numbers[3] = number%10;
        //numbers[1,9,8,3]
        return numbers;
    }

    public static void reverse(int[] numbers){
        for (int i = 0,j = numbers.length-1; i < j; i++,j--) {
            int temp = numbers[j];
            numbers[j] = numbers[i];
            numbers[i] = temp;
        }
        //numbers[8,3,4,6]
    }
}

数组拷贝

package com.item.huang;

//数组拷贝（得到一个和原数组一摸一样的数组）
public class Test05 {
    public static void main(String[] args) {
        int[] array = {11,22,33};
        int[] array2 = copy(array);
        printArray(array2);
    }
    public static int[] copy(int[] array){
        //创建新数组array2
        int[] array2 = new int[array.length];
        //将原数组array的元素拷贝给新数组array2
        for (int i = 0; i < array.length; i++) {
            array2[i] = array[i];
        }
        //返回新数组array2[11,22,33]
        return array2;
    }
    public static void printArray(int[] array){
        System.out.print("[");
        for (int i = 0; i < array.length; i++) {
            System.out.print(i==array.length-1 ? array[i] : array[i]+",");
        }
        System.out.print("]");
    }
}

抢红包

package com.item.huang;

import java.util.Random;

//抢红包
public class Test06 {
    public static void main(String[] args) {
    int[] moneys = {6,88,199,520,1314};
    start(moneys);
    }
    public static void start(int[] moneys){
        //moneys[6,88,199,520,1314]
        //Random函数随机产生下标
        Random r = new Random();
        //采用交换规则-打乱原数组
        int temp = 0;
        for (int i = 0; i < moneys.length; i++) {
            int index = r.nextInt(moneys.length); //index: 0-moneys.length-1
            temp = moneys[index];
            moneys[index] = moneys[i];
            moneys[i] = temp;
        }
        //按照新数组顺序发红包
        for (int i = 0; i < moneys.length; i++) {
            System.out.println("恭喜你抢到"+moneys[i]+"元红包");
        }
    }

}

找素数

package com.item.huang;

//找素数 101-200
//采用多个方法可以简化问题
public class Test07 {
    //遍历101-200,将素数打印出来
    public static void main(String[] args) {
        //记录素数的个数
        int count = 0;
        for (int i = 101; i <= 200 ; i++) {
            if(check(i)){
                System.out.println(i);
                count++;
            }
        }
        System.out.println("总共有"+count+"个素数");
    }
    //判断该数是否为素数，是返回true,不是则返回false
    public static boolean check(int data) {
        for (int i = 2; i <= data / 2; i++) {
            if (data % i == 0) {
                return false;
            }
        }
        return true;
    }

}

打印9*9乘法表

package com.item.huang;

//打印9*9乘法表
//计算机只能一行一行的打印数据
public class Test08 {
    public static void main(String[] args) {
        for (int i = 1; i <= 9 ; i++) {
            for (int j = 1; j <= i ; j++) {
                //j 列 i 行
                System.out.print(j + "X" + i + "=" + (j*i) + "\t");
            }
            System.out.println();
        }
    }
}

打印三角形

package com.item.huang;

//打印三角形
//计算机只能一行一行的打印数据
public class Test09 {
    public static void main(String[] args) {
        // n 代表打印的行数
        int n = 4;
        //1.循环打印 n 行
        for (int i = 1; i <= n ; i++) {
            //2.先打印空格
            for (int j = 1; j <= n-i ; j++) {
                System.out.print(" ");
            }
            //3.再打印星星
            //如果列数为偶数，打印空格否则打印星星（使用三元运算符)
            for (int j = 1; j <= 2*i-1 ; j++) {
                System.out.print(j%2==0 ? " " : "*");
            }
            //4.最后换行
            System.out.println();
        }
    }
}

双色球案例

package com.item.huang;

import com.sun.deploy.panel.ITreeNode;

import java.util.Random;
import java.util.Scanner;

//双色球
public class Test10
{
    //main方法
    public static void main(String[] args) {
        int[] userNumbers = userSelectNumbers();
        printArray(userNumbers);
        int[] luckyNumbers = randomLuckyNumbers();
        printArray(luckyNumbers);
        outcome(userNumbers,luckyNumbers);
    }
    //用户投注号码
    public static int[] userSelectNumbers(){
        //创建一个数组存储投注号码
        int[] userNumbers = new int[7];
        Scanner sc = new Scanner(System.in);
        //1.先投注红球号码
        for (int i = 0; i < userNumbers.length-1; i++) {
            while (true) {
                System.out.println("请输入一个红球号码（1-33之间）：");
                sc.hasNextInt();
                int number = sc.nextInt();
                if(number<1||number>33){
                    System.out.println("输入红球号码有误!");
                }else{
                    if(repeat(userNumbers,number)){
                        System.out.println("输入红球号码重复!");
                    }else {
                        userNumbers[i] = number;
                        System.out.println("该次投注红球号码为"+number);
                        break;//结束这次投注红球号码
                    }
                }
            }
        }
        //2.再投注蓝球号码
        while (true) {
            System.out.println("请输入一个蓝球号码(1-16)之间：");
            sc.hasNextInt();
            int number = sc.nextInt();
            if(number<1||number>16){
                System.out.println("输入的蓝球号码错误！");
            }else {
                userNumbers[6] = number;
                System.out.println("该次投注蓝球号码为"+number);
                break;//结束这次投注蓝球号码
            }
        }
        return userNumbers;
    }
    //随机中奖号码
    public static int[] randomLuckyNumbers(){
        int[] luckyNumbers = new int[7];
        Random r = new Random();
        //1.随机生成红球中奖号码（1-33）
        for (int i = 0; i < luckyNumbers.length-1; i++) {
            while (true) {
                int number = r.nextInt(33)+1;
                if (!repeat(luckyNumbers,number)){
                    luckyNumbers[i] = number;
                    break;
                }
            }
        }
        //2.随机生成蓝球中奖号码（1-16）
        int number = r.nextInt(16)+1;
        luckyNumbers[6] = number;
        return luckyNumbers;
    }
    //中奖情况
    public static void outcome(int[] userNumbers,int[] luckyNumbers){
    int redCount = 0;
    int blueCount = 0;
    //1.计算红球中将个数
        for (int i = 0; i < userNumbers.length-1; i++) {
            for (int j = 0; j < luckyNumbers.length-1; j++) {
                if(userNumbers[i] == luckyNumbers[j]){
                    redCount++;
                    break;
                }
            }
        }
    //2.计算蓝球的中奖个数
        if(userNumbers[6] == luckyNumbers[6]){
            blueCount++;
        }
    //3.统计中奖结果
    if (redCount == 6 && blueCount == 1){
        System.out.println("恭喜中奖1000万");
    }else {
        if (redCount ==6 && blueCount == 0){
            System.out.println("恭喜中奖500万");
        }else {
            if (redCount == 5 && blueCount == 1){
                System.out.println("恭喜中奖3000元");
            }else{
                if (redCount == 5 && blueCount == 0 || redCount == 4 && blueCount == 1){
                    System.out.println("恭喜中奖200元");
                }else {
                    if (redCount == 4 && blueCount == 0 || redCount == 3 && blueCount == 1){
                        System.out.println("恭喜中奖10元");
                    }else{
                        if (redCount < 3 && blueCount == 1){
                            System.out.println("恭喜中奖5元");
                        }else {
                            System.out.println("谢谢参与!");
                        }
                    }
                }
            }
        }
    }
    }
    //判断红球号码是否重复
    public static boolean repeat(int[] userNumbers,int number){
        for (int i = 0; i < userNumbers.length-1; i++) {
            if (number == userNumbers[i]){
                return true;
            }
        }
        return false;
    }
    //打印数组
    public static void printArray(int[] array){
        System.out.print("[");
        for (int i = 0; i < array.length; i++) {
            System.out.print(i==array.length-1 ? array[i] : array[i]+"," );
        }
        System.out.println("]");
    }
}