Java 注冊后登錄界面程序，異常判斷是否為空等，ArrayList，學生類，集合【詩書畫唱】
制作注冊后登錄界面，使用異常判斷用戶輸入是否為空，輸入內容長度是否大于6位數(shù)，密碼是否為空，年齡是否滿18（使用異常制作）
package fuXi;
import java.util.Scanner;
public class yichang {
public static void main(String[] args) {
yonghu yh = new yonghu();
while (true) {
System.out.println("請輸入你的操作:1.登錄? 2.注冊");
Scanner s = new Scanner(System.in);
int num = s.nextInt();
if (num == 1) {
System.out.println("----執(zhí)行登錄操作----");
System.out.println("請輸入用戶名:");
String uname = s.next();
try{
if(uname.length()<6){throw new StringIndexOutOfBoundsException("詩書畫唱提醒你，"
+ "輸入內容長度已經(jīng)小于6");
}
else{System . out. println("輸入內容長度已經(jīng)不小于6，輸入成功！");
}
} catch (StringIndexOutOfBoundsException e) {
System. out. println("詩書畫唱提醒你，輸入內容長度已經(jīng)小于6，為確保你的安全，"
+ "最好大于6位數(shù)！且密碼不能為空！");
}
System.out.println("請輸入你的密碼");
String pwd = s.next();
System.out.println("請輸入你的年齡");
int age = s.nextInt();
try{
if(age<18){throw new Exception("詩書畫唱提醒你，你未滿18歲，不能玩和購買這款游戲！");
}else{System . out. println("詩書畫唱提醒你，年齡設置成功！");}
}
catch (Exception e) {
System. out. println("詩書畫唱警告你，你未滿18歲！");
}
if (uname.equals(yh.uname) && pwd.equals(yh.pwd)&& age ==yh.age) {
System.out.println("登錄成功!");
break;
} else {
System.out.println("登錄失敗，你未注冊，請先注冊 ");
}
} else if (num == 2) {
System.out.println("----執(zhí)行注冊操作----");
System.out.println("請輸入用戶名:");
String uname = s.next();
System.out.println("請輸入你的年齡");
int age = s.nextInt();
try{
if(age<18){throw new Exception("詩書畫唱提醒你，你未滿18歲，不能玩和購買這款游戲！");
}else{System . out. println("詩書畫唱提醒你，年齡設置成功！");}
}
catch (Exception e) {
System. out. println("詩書畫唱警告你，你未滿18歲！");
}
System.out.println("請輸入你的密碼（最好輸入內容長度大于6位數(shù)，不能為空）");
String pwd = s.next();
//pwd=null;
try{
if(pwd.length()<6){throw new StringIndexOutOfBoundsException("詩書畫唱提醒你，密碼不能小于6位數(shù)！");
/*拋出異常*/
}
else{System . out. println("詩書畫唱提醒你，密碼設置成功！");}
} catch (StringIndexOutOfBoundsException e) {
System. out. println("詩書畫唱提醒你，輸入內容長度不大于6位數(shù)，為確保你的安全，"
+ "必須大于6位數(shù)！且密碼不能為空！");
}
catch (NullPointerException e) {
System. out. println("詩書畫唱提醒你，密碼不能為空！");
}
System.out.println("因為國家法律，要實名認證，請輸入你的真實姓名");
String name = s.next();
yh.uname = uname;
yh.pwd = pwd;
yh.name = name;
yh.age = age;
System.out.println("注冊成功!");
}?
}
}
}
class yonghu {
String uname;
String pwd;
String name;
int age;
}
用ArrayList:創(chuàng)建一個學生類，包含學生編號，姓名，性別，成績，將學生放入類集合中，添加5名學生，算出學生的平均成績
package fuXi;
import java.util.ArrayList;
public class jiHe {
public static void main(String[] arrgs) {
ArrayList s = new ArrayList();
student A1 = new student("點贊編號ID:233", "詩名", '男', 100);
student A2 = new student("點贊編號ID:666", "書名", '男', 100);
student A3 = new student("點贊編號ID:999", "畫名", '男', 100);
student A4 = new student("點贊編號ID:888", "唱名", '男', 100);
student A5 = new student("點贊編號ID:20U(喲)~", "帥名", '男', 100);
s.add(A1);
s.add(A2);
s.add(A3);
s.add(A4);
s.add(A5);
double ChengJiZongHe = 0;
for (int i = 0; i < s.size(); i++) {
student k = (student) s.get(i);
ChengJiZongHe += k.chengji;
}
System.out.println("學生的平均成績:" + ChengJiZongHe / s.size());
}
}
class student {
String ID;
String name;
char sex;
double chengji;
public student(String ID, String name, char sex, double chengji) {
this.ID = ID;
this.name = name;
this.sex = sex;
this.chengji = chengji;
}
}
