package bwk;
import java.util.Random;
public class Mjdu {
public static void main(String[] args) {
// TODO Auto-generated method stub
Random r1 = new Random();
System.out.print("随机数为:");
for(int i=1;i<=10;i++) {
int sj = r1.nextInt(100);
System.out.print(" "+sj);
}
}
}
![](https://img2020.cnblogs.com/blog/1962599/202005/1962599-20200528143304869-5353918.png)
package bwk;
import java.text.SimpleDateFormat;
import java.util.Date;
public class Mjdu {
public static void main(String[] args) {
// TODO Auto-generated method stub
SimpleDateFormat s1 = new SimpleDateFormat("Gyyyy年MM月dd日");
SimpleDateFormat s2=new SimpleDateFormat("今天是Gyyyy年的第D天,E");
Date d=new Date();
String a=s1.format(d);
String b=s2.format(d);
System.out.println(a+' '+b);
}
}
![](https://img2020.cnblogs.com/blog/1962599/202005/1962599-20200528143512880-887283314.png)
package bwk;
import java.util.Scanner;
public class Mjdu {
public static void main(String[] args) {
// *3.输入一个邮箱地址,判断是否合法.如果合法,输出用户名. 合法:必须包含@ 和 . 并且.在@的后面 (用indexof)
Scanner input=new Scanner(System.in);
System.out.print("请输入合法的邮箱:");
String str =input.nextLine();
int count=0;
int count2=0;
int x=0;
int y=0;
for(int j=0;j<str.length()-1;j++) {
String str1=str.substring(j,j+1);
if(str1.contentEquals("@")) {
count++;
x=j;
}
if(str1.contentEquals(".")) {
count2++;
y=j;
}
}
if(count==1&&count2==1&&x<(y-1)&&x!=0&&y!=str.length()-1) {
System.out.println("合法");
}else {
System.out.println("不合法");
}
![](https://img2020.cnblogs.com/blog/1962599/202005/1962599-20200528143735243-2114845208.png)