/**
 * @ClassName: ScoreMaster
 * @Description: TODO
 * @Author: AI悦创
 * @Date: 2022/10/9 19:24
 * @Version: V1.0
 * @Blog: https://www.bornforthis.cn
 */

import java.util.Scanner;

public class ScoreMaster {
    public static void main(String[] args) {

        // 声明六个变量， 分别代表六门科目的成绩
        int YuWenIndex = 0;
        int ShuXueIndex = 1;
        int WaiYuIndex = 2;
        int WuLiIndex = 3;
        int HuaXueIndex = 4;
        int ShengWuIndex = 5;

        int totalScoreCount = 6;

        // 每门课的名字
        String[] names = new String[totalScoreCount];
        names[YuWenIndex] = "语文";
        names[ShuXueIndex] = "数学";
        names[WaiYuIndex] = "外语";
        names[WuLiIndex] = "物理";
        names[HuaXueIndex] = "化学";
        names[ShengWuIndex] = "生物";

        Scanner scanner = new Scanner(System.in);

        System.out.println("请输入共有多少年的成绩：");

        int yearCount = scanner.nextInt();

        double[][] scores = new double[yearCount][totalScoreCount];  // 看几年的数组

        for (int i = 0; i < yearCount; i++) {
            for (int j = 0; j < totalScoreCount; j++) {
                scores[i][j] = 80 + Math.random() * 20;
                System.out.println("第" + (i + 1) + "年" + names[j] + "成绩为：" + scores[i][j]);
            }
        }

        boolean cont = true;
        while (cont) {
            System.out.println("请选择要进行的操作：");
            System.out.println("1: 求某年最好成绩\n" +
                    "2: 求某年的平均成绩\n" +
                    "3: 求所有年份最好成绩\n" +
                    "4: 求某门课历年最好成绩");

            int oprtId = scanner.nextInt();

            int year = 0;  // 在 switch 用一块代码块里，不能声明同一个变量，所以直接写在外面，方便。不然得想不同的变量名。
            switch (oprtId) {
                // 先编写 case
                case 1:
                    // 让用户输入指定的年份
                    System.out.println("请输入要计算第几年的最好成绩");
                    year = scanner.nextInt();
                    if (year <= 0 || yearCount < year) {
                        System.out.println("非法的年份：" + year);
                        cont = false;
                        break;
                    }
                    year = year - 1;
                    // 指定年份的最好成绩的编号，开始假设是0
                    int bestOfYearScoreId = 0;
                    // 循环指定年份的成绩，找出最好的成绩
                    // TODO：如果有两门课的成绩一样，而且都是最高的，怎么办？
                    for (int i = 1; i < totalScoreCount; i++) {
                        if (scores[year][bestOfYearScoreId] < scores[year][i]) {
                            bestOfYearScoreId = i;
                        }
                    }
                    System.out.println("第" + (year + 1) + "年成绩最好的科目为" + names[bestOfYearScoreId] + "，成绩为" + scores[year][bestOfYearScoreId] + "。");
                    break;
                case 2:
                    System.out.println("请输入要计算第几年的平均成绩");
                    year = scanner.nextInt();
                    if (year <= 0 || yearCount < year) {
                        System.out.println("非法的年份：" + year);
                        cont = false;
                        break;
                    }
                    year = year - 1;
                    double totalCountForAvg = 0;
                    for (int i = 0; i < totalScoreCount; i++) {
                        totalCountForAvg += scores[year][i];
                    }
                    double avgOfYear = totalCountForAvg / totalScoreCount;
                    System.out.println("第" + (year + 1) + "年的平均成绩为" + avgOfYear + "。");
                    break;
                case 3:
                    int bestYear = 0;
                    int bestScore = 0;

                    for (int i = 0; i < yearCount; i++) {
                        for (int j = 0; j < totalScoreCount; j++) {
                            if (scores[bestYear][bestScore] < scores[i][j]) {
                                bestYear = i;
                                bestScore = j;
                            }
                        }
                    }
                    // 视频中代码有错误，应该是使用 bestYear 而不是 year， 鸣谢 @zZGod 帮忙揪出 bug 一只。
                    System.out.println("所有年度最好成绩为第" + (bestYear + 1) + "年的" + names[bestScore] + "，成绩为" + scores[bestYear][bestScore] + "。");
                    break;
                case 4:
                    System.out.println("请输入科目编号");
                    int subjectId = scanner.nextInt();
                    if (subjectId <= 0 || totalScoreCount < subjectId) {
                        System.out.println("非法的科目编号：" + subjectId);
                        cont = false;
                        break;
                    }
                    subjectId = subjectId - 1;
                    year = 0;
                    for (int i = 1; i < yearCount; i++) {
                        if (scores[year][subjectId] < scores[i][subjectId]) {
                            year = i;
                        }
                    }
                    System.out.println("第" + (year + 1) + "年度" + names[subjectId] + "成绩最好，为" + scores[year][subjectId] + "。");

                    break;
                default:
                    cont = false;
                    System.out.println("不支持：" + oprtId + "， 程序结束。");
            }
        }

    }
}

import java.util.Scanner;

public class OneYearOneArray {
    public static void main(String[] args) {
        // 声明六个变量， 分别代表六门科目的成绩
        int YuWenIndex = 0;
        int ShuXueIndex = 1;
        int WaiYuIndex = 2;
        int WuLiIndex = 3;
        int HuaXueIndex = 4;
        int ShengWuIndex = 5;

        // 每门课的名字
        String[] names = new String[6];
        names[YuWenIndex] = "语文";
        names[ShuXueIndex] = "数学";
        names[WaiYuIndex] = "外语";
        names[WuLiIndex] = "物理";
        names[HuaXueIndex] = "化学";
        names[ShengWuIndex] = "生物";

        // 每门课的成绩
        double[] year1 = new double[6];

        // 用随机数给成绩赋值
        for (int i = 0; i < 6; i++) {
            year1[i] = 80 + Math.random() * 20;
        }

        // 每门课的成绩
        double[] year2 = new double[6];

        // 用随机数给成绩赋值
        for (int i = 0; i < 6; i++) {
            year2[i] = 80 + Math.random() * 20;
        }

        // 每门课的成绩
        double[] year3 = new double[6];

        // 用随机数给成绩赋值
        for (int i = 0; i < 6; i++) {
            year3[i] = 80 + Math.random() * 20;
        }

        double[] yearToUse;

        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入要查看第几年的成绩：");
        int year = scanner.nextInt();

        switch (year) {
            case 1:
                yearToUse = year1;
                break;
            case 2:
                yearToUse = year2;
                break;
            case 3:
                yearToUse = year3;
                break;
            default:
                System.out.println("输入的年份不对，将查看的是最新一年的成绩");
                yearToUse = year3;
                break;

        }

        System.out.println("请输入要查看的成绩编号：");

        int scoreIndex = scanner.nextInt();

        System.out.println("第" + year + "年的" + names[scoreIndex] + "的成绩是：" + yearToUse[scoreIndex]);

    }
}

import java.util.Scanner;

public class UseVariable {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);

        int a;
        System.out.println("创建了变量 a，输入一个整数：");
        a = in.nextInt();
        System.out.println("给 a 赋值，a 的值为" + a + "，请再次输入一个整数：");

        a = in.nextInt();
        System.out.println("再次给赋值，现在 a 的值为" + a);
    }
}

public class SevenScore {
    public static void main(String[] args) {
        // 声明六个变量， 分别代表六门科目的成绩
        int YuWen = 0;
        int ShuXue = 0;
        int WaiYu = 0;
        int WuLi = 0;
        int HuaXue = 0;
        int ShengWu = 0;
    }
}

public class IfElseNum {
    public static void main(String[] args) {

        int n = 1;

        String ret = n + "对应的汉字是";
        if (n == 0) {
            ret = ret + "零";
        } else if (n == 1) {
            ret = ret + "壹";
        } else if (n == 2) {
            ret = ret + "贰";
        } else if (n == 3) {
            ret = ret + "叁";
        } else if (n == 4) {
            ret = ret + "肆";
        } else if (n == 5) {
            ret = ret + "伍";
        } else if (n == 6) {
            ret = ret + "陆";
        } else if (n == 7) {
            ret = ret + "柒";
        } else if (n == 8) {
            ret = ret + "捌";
        } else if (n == 9) {
            ret = ret + "玖";
        } else {
            System.out.println("错误的值" + n + "。值需要在大于等于1，小于等于9。");
        }

        System.out.println(ret);
    }
}

public class demo {
    public static void main(String[] args) {
        int a = 1;
        int a = 2;
    }
}
// 输出：
java: 已在方法 main(java.lang.String[])中定义了变量 a

public class AssignFirst {
    public static void main(String[] args) {
        int a;
        int b = a + 1; // 其实就是没有初始化
        /*java: 可能尚未初始化变量a
        * 初始化，就是你要给他赋值，你创建变量的时候要给它一个值。
        * 如果你不用这个变量 a 直接声明变量也是可以的*/
    }
}

/*
 * project = 'Java_Coder', file_name = '笔记', author = 'AI悦创'
 * time = '2020/5/8 下午6:15', product_name = IntelliJ IDEA, 公众号：AI悦创
 * code is far away from bugs with the god animal protecting
 *    I love animals. They taste delicious.
 */

public class notes {
	public static void main(String[] args){
		boolean a = true;
		boolean b = false;
		
		System.out.println(a & b); // & 且 （and）
		System.out.println(a && b); // && 且且 （andand）
		System.out.println(a | b); // | 或 （or）
		System.out.println(a || b); // | 或或 （oror）
		// 对比
		System.out.println(a || (10 / 0 > 1));
		System.out.println(a | (10 / 0 > 1));
	}
}

public class BigNumber {
    public static void main(String[] args) {
        int bigNum = 9999999999;  // 会报错：java: 整数太大
        long number = 9999999999L;  // 解决方法
    }
}

String myStr = "Hello";
char result = myStr.charAt(0);
System.out.println(result);  // H