import java.util.Scanner;

public class MethodScanner {

    public static void main(String[] args) {

        Scanner scanner = new Scanner(System.in);

        int intScanner = scanner.nextInt(); // 读取下个整数
        double doubleScanner = scanner.nextDouble(); // 读取下个双精度浮点数
        String stringScanner1 = scanner.next(); // 读取下个单词！
        String stringScanner2 = scanner.nextLine(); // 读取下个句子

        while (scanner.hasNext()) { // 实现循环输入
            String name = scanner.next();
            if (name.equalsIgnoreCase("quit")) {
                break;
            }
        }

        scanner.close(); // 释放资源
    }

}

import java.util.Random;

public class MethodRandom {

    public static void main(String[] args) {

        Random random = new Random(); // 不加参数，以时间戳为种子
        Random seedRandom = new Random(123); // 以123为种子生成随机数

        // 生成整数
        int intRandom1 = random.nextInt(); // 生成所有范围的整数
        int intRandom2 = random.nextInt(100); // 生成[0, 100)范围的整数
        int intRandom3 = random.nextInt(1, 100); // 生成指定范围的整数
        System.out.println(intRandom1 + " " + intRandom2 + " " + intRandom3);

    }

}

import java.time.LocalDateTime;
import java.time.Month;
import java.time.format.DateTimeFormatter;

public class MethodDate {

    public static void main(String[] args) { // LocalDateTime 和 LocalDate 类

        // 生成当前日期
        LocalDateTime now = LocalDateTime.now();
        System.out.println(now);
        System.out.println("============================================================");

        // 生成指定日期
        LocalDateTime dateTime1 = LocalDateTime.of(2024, 1, 2, 3, 4, 5);
        System.out.println(dateTime1);
        System.out.println("============================================================");

        // 字符串日期转换
        LocalDateTime parse = LocalDateTime.parse("2024-01-01T08:01:01"); // 固定格式
        System.out.println(parse);
        System.out.println("============================================================");

        // 获取年月日时分秒
        int year = dateTime1.getYear();
        Month month = dateTime1.getMonth();
        int day = dateTime1.getDayOfMonth();
        int hour = dateTime1.getHour();
        int minute = dateTime1.getMinute();
        int second = dateTime1.getSecond();
        System.out.println(year + " " + month.getValue() + " " + day + " " + hour + " " + minute + " " + second);
        System.out.println("============================================================");

        // 更改时间格式
        String stringDate = "2021-01-01 08:01:01";
        DateTimeFormatter dateTimeFormatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss"); // 创建格式转换器 固定格式
        LocalDateTime dateTime2 = LocalDateTime.parse(stringDate, dateTimeFormatter); // 将时间转换为指定格式
        System.out.println(dateTime2);
        System.out.println("============================================================");

        // 获取本周第几天，本月第几天，本年第几天
        System.out.println(dateTime1); // 当前日期
        System.out.println(dateTime1.getDayOfWeek().getValue()); // 本周第几天 (不加getValue则显示周几)
        System.out.println(dateTime1.getDayOfMonth()); // 本月第几天
        System.out.println(dateTime1.getDayOfYear()); // 本年第几天
        System.out.println("============================================================");

        // 增加 / 减少日期，周，月，年
        LocalDateTime dateTime3 = dateTime1.plusDays(1); // 加一天
        System.out.println(dateTime3);

        LocalDateTime dateTime4 = dateTime1.minusDays(1); // 减一天
        System.out.println(dateTime4);
        System.out.println("============================================================");

        LocalDateTime dateTime5 = dateTime1.plusWeeks(1); // 加一周
        System.out.println(dateTime5);

        LocalDateTime dateTime6 = dateTime1.minusWeeks(1); // 减一周
        System.out.println(dateTime6);
        System.out.println("============================================================");

        LocalDateTime dateTime7 = dateTime1.plusMonths(1); // 加一月
        System.out.println(dateTime7);

        LocalDateTime dateTime8 = dateTime1.minusMonths(1); // 减一月
        System.out.println(dateTime8);
        System.out.println("============================================================");

        LocalDateTime dateTime9 = dateTime1.plusYears(1); // 加一年
        System.out.println(dateTime9);

        LocalDateTime dateTime10 = dateTime1.minusYears(1); // 减一年
        System.out.println(dateTime10);
        System.out.println("============================================================");


    }
}

import java.math.BigDecimal;
import java.math.MathContext;
import java.math.RoundingMode;

public class AboutBigDecimal {

    public static void main(String[] args) { // BigDecimal类 用于进行高精度浮点计算

        BigDecimal num1 = new BigDecimal("6.66"); // 用String类进行初始化

        BigDecimal num2 = new BigDecimal("3.34");

        // BigDecimal类的加减乘，运算后会生成新的BigDecimal对象
        BigDecimal add = num1.add(num2);
        BigDecimal sub = num1.subtract(num2);
        BigDecimal mul = num1.multiply(num2);
        System.out.println(add + " " + sub + " " + mul);

        // 通过 指定精度和舍入模式 实现除法
        BigDecimal div1 = num1.divide(num2, 3, RoundingMode.HALF_UP); // 保留小数点后 3 位，四舍五入（默认）
        System.out.println(div1);

        // 通过 MathContext 实现除法
        BigDecimal div2 = num1.divide(num2, new MathContext(4));
        System.out.println(div2);
    }

}