【2023级】智能医学工程专业-计算机程序设计-第03章-数据类型
作者: 阮晓龙 发布时间: 2024/9/4 7:28:55
基本信息：
章节名称：智能医学工程专业-计算机程序设计-第03章-数据类型
授课教师：信息技术学院互联网技术教学团队（与河南方和信息科技有限公司合作建设）
完成时间：2024年09月
适用年级：2023级
适用专业：智能医学工程
文档内容：
讲稿课件（教学版）：智能医学工程-计算机程序设计-课件-第03章-数据类型-教学版.pdf
讲稿课件（笔记版）：智能医学工程-计算机程序设计-课件-第03章-数据类型-笔记版.pdf
讲稿课件（在线版）：
学习资源：
代码：eg3.1
public class PrimitiveTypesDemo {
public static void main(String[] args) {
byte age = 18;
short year = 2024;
int population = 780000000;
long distance = 150000000000L;
float pi = 3.14f;
double e = 2.71828;
char grade = 'A';
boolean isJavaFun = true;
System.out.println("Age: " + age);
System.out.println("Year: " + year);
System.out.println("Population: " + population);
System.out.println("Distance: " + distance);
System.out.println("Pi: " + pi);
System.out.println("Euler's Number: " + e);
System.out.println("Grade: " + grade);
System.out.println("Is Java Fun: " + isJavaFun);
}
}代码：eg3.2
import java.util.*;
public class BuiltInTypesDemo {
public static void main(String[] args) {
String message = "Hello, Java!";
int[] numbers = {1, 2, 3, 4, 5};
System.out.println("Message: " + message);
System.out.print("Numbers: ");
for (int number : numbers) {
System.out.print(number + " ");
}
System.out.println();
List<Integer> list = new ArrayList<>();
list.add(1);
list.add(2);
list.add(3);
list.add(4);
list.add(5);
for (Integer number : list) {
System.out.println(">>>number = " + number);
}
}
}代码：eg3.3.1
public class StringDemo {
public static void main(String[] args) {
String greeting = "Hello";
String name = "World";
String message = greeting + ", " + name + "!";
System.out.println("Message: " + message);
System.out.println("Uppercase: " + message.toUpperCase());
System.out.println("Substring: " + message.substring(7));
//换一种写法
StringBuffer sb = new StringBuffer();
sb.append(greeting);
sb.append(", ");
sb.append(name);
sb.append("!");
System.out.println(">>>Substring: " + sb.toString());
}
}代码：eg3.3.2
public class StringBufferDemo {
public static void main(String[] args) {
StringBuffer sb = new StringBuffer("Hello");
sb.append(" World");
sb.insert(5, ",");
sb.replace(6, 11, "Java");
System.out.println(">>>StringBuffer: " + sb.toString());
}
}代码：eg3.4
public class WrapperClassDemo {
public static void main(String[] args) {
int num = 100;
Integer numObj = Integer.valueOf(num); // 将 int 转换为 Integer 对象
System.out.println("Primitive int: " + num);
System.out.println("Wrapper Integer: " + numObj);
// 自动装箱和拆箱
Integer autoBoxed = num; // 自动装箱
int autoUnboxed = autoBoxed; // 自动拆箱
System.out.println("Auto-boxed Integer: " + autoBoxed);
System.out.println("Auto-unboxed int: " + autoUnboxed);
}
}代码：eg3.5
import java.math.BigInteger;
public class BigIntegerDemo {
public static void main(String[] args) {
BigInteger bigNum1 = new BigInteger("123456789012345678901234567890");
BigInteger bigNum2 = new BigInteger("987654321098765432109876543210");
BigInteger sum = bigNum1.add(bigNum2);
BigInteger product = bigNum1.multiply(bigNum2);
System.out.println("Sum: " + sum);
System.out.println("Product: " + product);
}
}代码：eg3.6.1
import java.util.Date;
import java.text.SimpleDateFormat;
public class DateDemo {
public static void main(String[] args) {
Date now = new Date();
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
System.out.println("Current Date: " + sdf.format(now));
}
}代码：eg3.6.2
import java.util.Calendar;
public class CalendarDemo {
public static void main(String[] args) {
Calendar cal = Calendar.getInstance();
cal.add(Calendar.DAY_OF_MONTH, 5); // 加5天
System.out.println("Date after 5 days: " + cal.getTime());
}
}代码：eg3.6.3
//Java 8引入了全新的日期和时间API，这是因为旧版的java.util.Date和java.util.Calendar不够灵活和易用。以下是一些使用Java 8日期/时间特性的示例：
//获取当前日期和时间：
import java.time.LocalDateTime;
public class Main {
public static void main(String[] args) {
LocalDateTime now = LocalDateTime.now();
System.out.println(">>>当前日期和时间：" + now);
}
}
//解析和格式化日期：
import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
public class Main {
public static void main(String[] args) {
LocalDateTime now = LocalDateTime.now();
DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
// 格式化日期
String formattedDate = now.format(formatter);
System.out.println(">>>格式化后的日期：" + formattedDate);
}
}
//计算日期时间的差异：
import java.time.LocalDateTime;
import java.time.temporal.ChronoUnit;
public class Main {
public static void main(String[] args) {
LocalDateTime dateTime1 = LocalDateTime.of(2023, 1, 1, 10, 30);
LocalDateTime dateTime2 = LocalDateTime.now();
long daysDiff = ChronoUnit.DAYS.between(dateTime1, dateTime2);
System.out.println(">>>两个日期之间相差的天数：" + daysDiff);
}
}
//使用java.time.Duration计算时间差：
import java.time.Duration;
import java.time.LocalTime;
public class Main {
public static void main(String[] args) {
LocalTime time1 = LocalTime.of(10, 30);
LocalTime time2 = LocalTime.now();
Duration duration = Duration.between(time1, time2);
long secondsDiff = duration.getSeconds();
System.out.println(">>>两个时间之间相差的秒数：" + secondsDiff);
}
}
//使用java.time.Period计算日期差：
import java.time.LocalDate;
import java.time.Period;
public class Main {
public static void main(String[] args) {
LocalDate date1 = LocalDate.of(2023, 1, 1);
LocalDate date2 = LocalDate.now();
Period period = Period.between(date1, date2);
int yearsDiff = period.getYears();
int monthsDiff = period.getMonths();
int daysDiff = period.getDays();
System.out.println(">>>两个日期之间的差异：\n年份：" + yearsDiff + "\n月份：" + monthsDiff + "\n天数：" + daysDiff);
}
}软件资源：