目录

• 日期与时间
• • Date
  • SimpleDateFormat
  • Calendar概述
• JDK8新增日期类
• • 概述、LocalTime /LocalDate / LocalDateTime
  • Instant
  • DateTimeFormatter
  • Duration/Period
  • chronoUnit
• 包装类
• 正则表达式
• Arrays类
• • Arrays类概述，常用功能演示
  • Arrays类对于Comparator比较器的支持
• 常见算法
• • 选择排序
  • 二分查找
• Lambda表达式
• • Lambda概述
  • Lambda实战-简化函数式接口
  • Lambda表达式的省略规则

日期与时间

Date

package com.itzixin.d1_date;import java.util.Date;public class DateDemo1 {public static void main(String[] args) {Date d =new Date();System.out.println(d);long time = d.getTime();System.out.println(time);System.out.println("------------");Date d1 = new Date();System.out.println(d1);long time2 = System.currentTimeMillis();time2+=(60*60+121)*1000;Date d2 = new Date(time2);System.out.println(d2);Date d3 = new Date();d3.setTime(time2);System.out.println(d3);}
}

SimpleDateFormat

package com.itzixin.d2_simpledateformat;import java.text.SimpleDateFormat;
import java.util.Date;public class SimpleDateFormatDemo01 {public static void main(String[] args) {Date d =new Date();System.out.println(d);SimpleDateFormat sdf = new SimpleDateFormat("yyyy年MM月dd日 HH:mm:ss EEE a");String rs = sdf.format(d);System.out.println(rs);System.out.println("--------------");long time1 = System.currentTimeMillis()+121*1000;String rs2 = sdf.format(time1);System.out.println(rs2);System.out.println("-----------");}}

package com.itzixin.d2_simpledateformat;import java.sql.SQLOutput;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;public class SimpleDateFormatDemo2 {public static void main(String[] args) throws ParseException {String dateStr = "2021年08月06日 11:11:11";SimpleDateFormat sdf =new SimpleDateFormat("yyyy年MM月dd日 HH:mm:ss");Date d =sdf.parse(dateStr);long time  = d.getTime()+(2L*24*60*60+ 14*60*60 + 49*60+ 6)*6000;System.out.println(sdf.format(time));}
}

package com.itzixin.d2_simpledateformat;import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;public class SimpleDateFormatTest3 {public static void main(String[] args) throws ParseException {String startTime = "2021-11-11 00:00:00";String endTime = "2021-11-11 00:10:00";String xiaoJia = "2021-11-11 00:03:47";String xiaoPi = "2021-11-11 00:10:11";SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");Date d1 = sdf.parse(startTime);Date d2 = sdf.parse(endTime);Date d3 = sdf.parse(xiaoJia);Date d4 = sdf.parse(xiaoPi);if(d3.after(d1)&&d3.before(d2)){System.out.println("小佳秒杀成功，可以发货了");}else{System.out.println("小佳秒杀失败了");}if(d4.after(d1)&&d4.before(d2)){System.out.println("小皮秒杀成功，可以发货了");}else{System.out.println("小皮秒杀失败！");}}
}

Calendar概述

package com.itzixin.d2_simpledateformat;import java.util.Calendar;
import java.util.Date;public class d3_calendar {public static void main(String[] args) {Calendar cal = Calendar.getInstance();System.out.println(cal);int year = cal.get(Calendar.YEAR);System.out.println(year);int mm = cal.get(Calendar.MONTH)+1;System.out.println(mm);int days = cal.get(Calendar.DAY_OF_YEAR);System.out.println(days);cal.add(Calendar.DAY_OF_YEAR,66);cal.add(Calendar.MINUTE,59);Date d = cal.getTime();System.out.println(d);long time = cal.getTimeInMillis();System.out.println(time);}
}

JDK8新增日期类

概述、LocalTime /LocalDate / LocalDateTime

Instant

DateTimeFormatter

Duration/Period

chronoUnit

包装类

正则表达式

package com.itzixin.d6_regex;public class RegexDemo1 {public static void main(String[] args) {System.out.println(checkQQ("ofisjo33"));System.out.println(checkQQ("345534"));System.out.println(checkQQ(null));System.out.println("------------");System.out.println(checkQQ2("ofisjo33"));System.out.println(checkQQ2("345534"));System.out.println(checkQQ2(null));}public static boolean checkQQ2(String qq){return qq!=null && qq.matches("\\d{6,20}");}public static boolean checkQQ(String qq){if(qq==null || qq.length()<6||qq.length()>20){return false;}for(int i =0;ichar ch = qq.charAt(i);if(ch<'0'|| ch>'9'){return false;}}return true;}
}

package com.itzixin.d6_regex;import java.util.Scanner;public class RegexTest3 {public static void main(String[] args) {checkPhone();}private static void checkPhone() {Scanner sc = new Scanner(System.in);while(true){System.out.println("请您输入您的注册手机号码：");String phone = sc.next();if(phone.matches("1[3-9]\\d{9}")){System.out.println("手机号码格式正确，注册完成！");break;}else{System.out.println("格式有误！");}}}
}

package com.itzixin.d6_regex;public class RegexDemo4 {public static void main(String[] args) {String names = "小路gjojg蓉儿jjioaa过儿";String [] arrs = names.split("\\w+");for(int i = 0;iSystem.out.println(arrs[i]);}String names2 = names.replaceAll("\\w+","  ");System.out.println(names2);}
}

Arrays类

Arrays类概述，常用功能演示

package com.itzixin.d7_arrays;import java.util.Arrays;public class ArraysDemo1 {public static void main(String[] args) {int [] arr = {10,2,55,22,24,200};System.out.println(arr);System.out.println(Arrays.toString(arr));Arrays.sort(arr);System.out.println(Arrays.toString(arr));int index=Arrays.binarySearch(arr,55);System.out.println(index);int index2 = Arrays.binarySearch(arr,555);System.out.println(index2);int[] arr2={12,36,34,25,234}}
}

Arrays类对于Comparator比较器的支持

package com.itzixin.d7_arrays;import java.util.Arrays;
import java.util.Comparator;public class ArraysDemo2 {public static void main(String[] args) {int [] ages = {34,12,42,23};Arrays.sort(ages);System.out.println(Arrays.toString(ages));Integer[] ages1 = {34,12,42,23};Arrays.sort(ages1, new Comparator() {@Overridepublic int compare(Integer o1, Integer o2) {
//                if(o1>o2){
//                    return 1;
//                }else if(o1
//                    return -1;
//                }
//                return 0;
//                return o1-o2;return o2-o1;}});System.out.println(Arrays.toString(ages1));System.out.println("-------------");Student[] students = new Student[3];students[0] = new Student("吴磊",23,175);students[1]= new Student("谢欣",22,188);students[2]= new Student("王亮",18,222);System.out.println(Arrays.toString(students));Arrays.sort(students, new Comparator() {@Overridepublic int compare(Student o1, Student o2) {return o1.getAge()-o2.getAge();}});System.out.println(Arrays.toString(students));}
}

常见算法

选择排序

package com.itzixin.d8_sort_binarysearch;import java.util.Arrays;public class Test1 {public static void main(String[] args) {int [] arr = {5,1,3,2};for(int i =0;ifor(int j =i+1;jif(arr[i]>arr[j]){int temp = arr[i];arr[i]=arr[j];arr[j]=temp;}}}System.out.println(Arrays.toString(arr));}
}

二分查找

Lambda表达式

Lambda概述

package com.itzixin.d9_lambda;import java.sql.SQLOutput;public class LambdaDemo1 {public static void main(String[] args) {
//        Swimming s1 = new Swimming() {
//            @Override
//            public void swim() {
//                System.out.println("老师游泳六六六");
//            }
//        }Swimming s1 = () ->{System.out.println("老师游泳六六六");};go(s1);}private static void go(Swimming s) {System.out.println("开始了。。。");s.swim();System.out.println("结束。。。");}}@FunctionalInterface
interface Swimming{void swim();
}

Lambda实战-简化函数式接口

package com.itzixin.d9_lambda;import java.util.Arrays;public class LambdaDemo3 {public static void main(String[] args) {Integer [] ages1 = {34,12,42,23};Arrays.sort(ages1,(Integer o1,Integer o2)->{return o2-o1;});System.out.println(Arrays.toString(ages1));}
}

Lambda表达式的省略规则