Java（8題）：異常，通過try catch進(jìn)行處理，登錄，商品，使用jdbc進(jìn)行讀取，詳細(xì)圖析
1.要求輸入班級(jí)人數(shù)，人數(shù)必須是正整數(shù)。通過異常機(jī)制來處理下，提示輸入的人數(shù)不能為負(fù)數(shù)
package a;
import java.util.Scanner;
public class yichang {
public static void main(String[] args) {
try {
System.out.println("請(qǐng)輸入班級(jí)的人數(shù)");
Scanner s = new Scanner(System.in);
int renshu = s.nextInt();
if (renshu < 0) {
throw new RuntimeException("人數(shù)必須為正整數(shù)");
}
System.out.println("班級(jí)人數(shù)為" + renshu);
} catch (RuntimeException e) {
System.out.println("輸入的人數(shù)不能為負(fù)數(shù)");
}
}
}
2.定義一個(gè)數(shù)組長(zhǎng)度為3的數(shù)組，打印其數(shù)據(jù)，要求（使用異常制作）
package a;
public class yichang {
public static void main(String[] args) {
try {
int[] up=new int[3];
int num1=10;
int num2=1;
int num3=num1/num2;//除數(shù)為0的異常
up[0]=11;
up[1]=22;
up[2]=33;
up[3]=44;//下標(biāo)越界的異常
} catch (ArithmeticException e) {
//出現(xiàn)除數(shù)為0的時(shí)候執(zhí)行這塊的內(nèi)容
//除數(shù)為的操作
System. out. println("b站up主詩書畫唱提醒你，你的除數(shù)為0啦，快點(diǎn)贊！");
}catch(ArrayIndexOutOfBoundsException e1){
//下標(biāo)越界操作
System. out. println("b站up主詩書畫唱提醒你，下標(biāo)越界啦，快投幣！");
}
catch(Exception e2){
//其他異常
System. out. println( "b站up主詩書畫唱提醒你，出現(xiàn)了其他類型的異常，快三連，關(guān)注！");
}
}
}
3、創(chuàng)建Student對(duì)象，設(shè)置name和age屬性,在main方法中添加如下的代碼：
Student stu = null;
stu.setName("張三");
System.out.println("學(xué)生的姓名設(shè)置完畢");
4.請(qǐng)分析以上的代碼出現(xiàn)的錯(cuò)誤，并通過try catch進(jìn)行處理。
package a;
public class yichang {
public static void main(String[] args) {
try {
Student stu=null;
stu. setName("張三");
System . out. println("詩書畫唱提醒你，學(xué)生的姓名設(shè)置完畢");
} catch (Exception e) {
// TODO: handle exception
System. out. println("詩書畫唱提醒你，學(xué)生的姓名設(shè)置有誤");
}
}
class Student{
private String name;
private int age;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
}}
5.定義人的年齡不能大于100歲并小于1歲（使用異常制作）
package a;
import java.util.Scanner;
public class yichang {
public static void main(String[] args) {
try {System.out.println("請(qǐng)輸入年齡");
Scanner s=new Scanner(System.in);//聲明Scanner接收的類
int age= s.nextInt();//接收用戶輸入整形的數(shù)據(jù)
if(100<age||age<1){throw new Exception();
}
else{System . out. println("詩書畫唱提醒你，人的年齡設(shè)置完畢");}
} catch (Exception e) {
// TODO: handle exception
System. out. println("詩書畫唱提醒你，人的年齡不能大于100歲并不能小于1歲");
}
}
class shangpin{
private String name;
private int age;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age =age;
}
}}
//6.制作登錄界面，使用異常判斷用戶輸入是否為空，輸入內(nèi)容長(zhǎng)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 a;
import java.util.Scanner;
public class yichang {
public static void main(String[] args) {
che timegame = new huoche(1, "時(shí)間游戲", 30, 0, 3);
che mengame = new huoche(2, "爺們游戲", 50, 0, 5);
che? ?woman= new keche(3, "女人游戲", 40, 4, 0);
che run = new keche(4, "跑步游戲", 80, 10, 0);
che swim = new pika(5, "游泳游戲", 60, 2, 4);
che sing = new pika(6, "唱歌游戲", 100, 4, 8);
che[] c = new che[6];
c[0] = timegame;
c[1] = mengame;
c[2] = woman;
c[3] = run;
c[4] = swim;
c[5] = sing;
yonghu yh = new yonghu();
che[] c_zuche = null;
while (true) {
System.out.println("---------“詩書畫唱”名品牌游戲購(gòu)買系統(tǒng)-----------");
System.out.println("請(qǐng)輸入你的操作:1.登錄? 2.注冊(cè)? 3.跳出系統(tǒng)");
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(qǐng)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(nèi)容長(zhǎng)度已經(jīng)小于6");
/*拋出異常*/
}
else{System . out. println("輸入內(nèi)容長(zhǎng)度已經(jīng)不小于6");
}
} catch (StringIndexOutOfBoundsException e) {
// TODO: handle exception
System. out. println("詩書畫唱提醒你，輸入內(nèi)容長(zhǎng)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(qǐng)輸入你的密碼");
String pwd = s.next();
System.out.println("請(qǐng)輸入你的年齡");
int age = s.nextInt();
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");
}
} else if (num == 2) {
System.out.println("----執(zhí)行注冊(cè)操作----");
System.out.println("請(qǐng)輸入用戶名:");
String uname = s.next();
System.out.println("請(qǐng)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(gòu)買這款游戲！");
}else{System . out. println("詩書畫唱提醒你，年齡設(shè)置成功！");}
}
catch (Exception e) {
// TODO: handle exception
System. out. println("詩書畫唱警告你，你未滿18歲！");
}
System.out.println("請(qǐng)輸入你的密碼（最好輸入內(nèi)容長(zhǎng)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(shè)置成功！");}
} catch (StringIndexOutOfBoundsException e) {
// TODO: handle exception
System. out. println("詩書畫唱提醒你，輸入內(nèi)容長(zhǎng)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) {
// TODO: handle exception
System. out. println("詩書畫唱提醒你，密碼不能為空！");
}
System.out.println("因?yàn)閲?guó)家法律，要實(shí)名認(rèn)證，請(qǐng)輸入你的真實(shí)姓名");
String name = s.next();
yh.uname = uname;
yh.pwd = pwd;
yh.name = name;
yh.age = age;
System.out.println("注冊(cè)成功!");
} else if (num == 3) {
System.exit(0);
}
}
// 購(gòu)買游戲操作
while (true) {
System.out.println("歡迎," + yh.name + "請(qǐng)選擇你的操作:");
System.out
.println("1.查看游戲列表? 2.進(jìn)行購(gòu)買? 3.查看我的購(gòu)買總價(jià)格，總可在線玩人數(shù)，總可下線玩人數(shù) 4.跳出系統(tǒng)");
Scanner s1 = new Scanner(System.in);
int num = s1.nextInt();
if (num == 1) {
for (che i : c) {/* 相當(dāng)于for(int i=0；i<c.length；i++) */
i.jieshao();
}
} else if (num == 2) {
System.out.println("請(qǐng)輸入你要買的游戲數(shù)");
int num1 = s1.nextInt();
c_zuche = new che[num1];
for (int i = 0; i < num1; i++) {
System.out.println("請(qǐng)輸入第" + (i + 1) + "游戲的編號(hào)");
int bianhao = s1.nextInt();
switch (bianhao) {
case 1:
c_zuche[i] = timegame;
break;
case 2:
c_zuche[i] = mengame;
break;
case 3:
c_zuche[i] = woman;
break;
case 4:
c_zuche[i] = run;
break;
case 5:
c_zuche[i] = swim;
break;
case 6:
c_zuche[i] = sing;
break;
}
}
System.out.println("購(gòu)買成功!");
} else if (num == 3) {
if (c_zuche == null) {
System.out.println("你還沒有進(jìn)行購(gòu)買呢！");
} else {
int zongjiage = 0;
int zongkezaixianwanrenshu = 0;
int zongkexiaxianwanrenshu = 0;
for (che i : c_zuche) {
i.jieshao();
zongjiage += i.jiage;
zongkezaixianwanrenshu += i.zaikeliang;
zongkexiaxianwanrenshu += i.zaiwuliang;
}
System.out.println("總價(jià)格" + zongjiage + "總可在線玩人數(shù)" +
zongkezaixianwanrenshu + "總可下線玩人數(shù)" + zongkexiaxianwanrenshu);
}
} else {
System.exit(0);/* 終止系統(tǒng)，不可為break，break是跳出循環(huán) */
}
}
}
}
class yonghu {
String uname;
String pwd;
String name;
int age;
}
abstract class che {
int bianhao;
String name;
int jiage;
int zaikeliang;
int zaiwuliang;
public che(int bianhao, String name, int jiage, int zaikeliang,int zaiwuliang) {
this.bianhao = bianhao;
this.name = name;
this.jiage = jiage;
this.zaikeliang = zaikeliang;
this.zaiwuliang = zaiwuliang;
}
abstract void jieshao();
}
class huoche extends che {
public huoche(int bianhao, String name, int jiage,
int zaikeliang, int zaiwuliang) {
super(bianhao, name, jiage, zaikeliang, zaiwuliang);
}
void jieshao() {
System.out.println("編號(hào)" + this.bianhao + "\t名稱:" + this.name +
"\t價(jià)格" + this.jiage + "\t總可在線玩人數(shù)" + this.zaiwuliang);
}
}
class keche extends che {
public keche(int bianhao, String name, int jiage, int zaikeliang,
int zaiwuliang) {
super(bianhao, name, jiage, zaikeliang, zaiwuliang);
}
void jieshao() {
System.out.println("編號(hào)" + this.bianhao + "\t名稱:" +
this.name + "\t價(jià)格" + this.jiage + "\t總可下線玩人數(shù)" + this.zaikeliang);
}
}
class pika extends che {
public pika(int bianhao, String name, int jiage, int zaikeliang,
int zaiwuliang) {
super(bianhao, name, jiage, zaikeliang, zaiwuliang);
}
void jieshao() {
System.out.println("編號(hào)" + this.bianhao + "\t名稱:" +
this.name + "\t價(jià)格" + this.jiage + "\t總可在線玩人數(shù)" + this.zaikeliang + "總可下線玩人數(shù)" +
this.zaiwuliang);
}
}
7.定義商品類，判斷商品的價(jià)格是否大于100并小于500（使用異常制作）
package a;
import java.util.Scanner;
public class yichang {
public static void main(String[] args) {
try {System.out.println("請(qǐng)輸入商品的價(jià)格");
Scanner s=new Scanner(System.in);//聲明Scanner接收的類
int jiage= s.nextInt();//接收用戶輸入整形的數(shù)據(jù)
if(500<jiage||jiage<100){throw new Exception();
}
else{System. out. println("詩書畫唱提醒你，商品的價(jià)格大于100并小于500");}
} catch (Exception e) {
// TODO: handle exception
System. out. println("詩書畫唱提醒你，商品的價(jià)格不大于100并且不小于500");
}
}
class shangpin{
private String name;
private int jiage;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getJiage() {
return jiage;
}
public void setJiage(int jiage) {
this.jiage =jiage;
}
}}
//JDBC作業(yè):
//1.建立一張數(shù)據(jù)庫表stu，包含編號(hào)，姓名，年齡，性別，成績(jī)屬性，使用jdbc進(jìn)行讀取數(shù)據(jù)庫中的數(shù)據(jù)
package a;
import java.sql.*;
public class yichang {
public static void main(String[] args) {
// TODO Auto-generated method stub
//Jar:各個(gè)數(shù)據(jù)庫廠商都實(shí)現(xiàn)了ODBC規(guī)范，形成了自己的API,就是我們導(dǎo)入的這個(gè)jar包
// 1.加載數(shù)據(jù)庫驅(qū)動(dòng)(非運(yùn)行時(shí)的異常)
try {
Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver");
// 2.建立連接(參數(shù)三個(gè),1用戶名? ?2密碼? ?3數(shù)據(jù)庫名稱)
//這個(gè)鏈接數(shù)據(jù)庫也要拋異常，為了方便，我將所有異常一塊拋出
Connection con=DriverManager.getConnection("jdbc:sqlserver://DESKTOP-49FTFSP;"
+ "databaseName=stud","sa","1234abcd");
// 3.執(zhí)行SQL語句
String sql="select * from Student";
Statement sta=con.createStatement();
// 4.獲取結(jié)果(存入到數(shù)據(jù)連接池中)
ResultSet res=sta.executeQuery(sql);
// 5.遍歷結(jié)果
while(res.next()){
System.out.print(res.getObject("Id")+"? ?");
System.out.print(res.getObject("Name")+"? ?");
System.out.print(res.getObject("Gender")+"? ?");
System.out.print(res.getObject("Height")+"? ?");
System.out.print(res.getObject("Weight")+"? ?");
System.out.print(res.getObject("Age")+"? ?");
System.out.print(res.getObject("Class")+"? ?");
System.out.println();
}
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
類比替換法。
相關(guān)知識(shí)圖：
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