流程控制语句（上）

if 语句 条件判断语句

if (逻辑运算 条件判断) 语句;

if (逻辑运算 条件判断)
语句;

if (逻辑运算 条件判断){
语句一;
语句二;
语句三;
}

if(true){
//true执行代码
}else{
//false执行代码
}

if(){
//
}else if(){

}else if(){

}else{

}
int score = 68;
// >=90 优秀 >=80 良好 >=60 及格 >60 补考

if (score >= 90) {
System.out.println("优秀");
} else if (score >= 80) {
System.out.println("良好");
} else if (score >= 60) {
System.out.println("及格");
} else {
System.out.println("补考");
}

Date
LocalDate java8
Calendar c = Calendar.getInstance();

// Date d = new Date();
// int w = d.getDay();

LocalDate now = LocalDate.now();
// System.out.println(now.getDayOfWeek().getDisplayName(TextStyle.FULL,
// Locale.getDefault()));
int w = now.getDayOfWeek().getValue();// 1-7 星期天

if (w == 0 || w == 7)
System.out.println("星期日"); 
if (w == 1)
System.out.println("星期一");
if (w == 2)
System.out.println("星期二");
if (w == 3)
System.out.println("星期三");
if (w == 4)
System.out.println("星期四");
if (w == 5)
System.out.println("星期五");
if (w == 6)
System.out.println("星期六");        注意输出会全部执行。

 

 

 

CanDemo.java:

import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;

public class CanDemo {

public static void main(String[] args) {
Calendar c = Calendar.getInstance();
c.set(1200,12,23);
System.out.println(c.get(Calendar.YEAR)-1);
System.out.println(c.get(Calendar.MONTH));
System.out.println(c.get(Calendar.DATE));

System.out.println(c.get(Calendar.DAY_OF_MONTH));

//c.getTime() 返回一个Date

System.out.println(System.currentTimeMillis());
System.out.println(new Date().getTime());
System.out.println(Calendar.getInstance().getTimeInMillis());


SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss S");
System.out.println(sdf.format(new Date()));

}

}

 

DateDemo.java:

import java.util.Date;

public class DateDemo {

public static void main(String[] args) {
// Date d = new Date();

System.out.println(new Date().getTime());

// 1589964507256 时间戳

// Date d = new Date(1589964507256L);

//千年虫 2000 bug 1997 97- 1967 9999 99 99 99 99
Date d = new Date();
System.out.println(d.getYear());
System.out.println(System.getProperty("java.version"));
System.out.println(d.getMonth());
System.out.println(d.getDate());
System.out.println(d.getHours());
System.out.println(d.getMinutes());
System.out.println(d.getSeconds());

}

}