异常+异常链

try{
//代码段(此处不会出现异常)
}catch(异常Exception或Exception的子类){
//对异常进行处理的代码段
}
//代码段
}
    public class Test1 {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        System.out.print("请输入被除数:");
//        除数为0异常: ArithmeticException
//        输入格式不正确: InputMismathException(子类)
        try{
            //程序中可能出现异常的代码
            int num1 = in.nextInt();
            System.out.print("请输入除数:");
            int num2 = in.nextInt();
            System.out.println(num1+"/"+ num2 +"="+ num1/ num2);
        }catch(ArithmeticException e){
            //在程序出现异常的情况下执行的代码
            System.err.print("出现错误操作"+"\n");
            //异常对象 e printStackTrace();打印异常堆栈信息
            e.printStackTrace();
        }
        System.out.println("感谢使用本程序！");

    }
}

try{
//代码块
}cetch(){
//代码块
}finally{
//代码块
}


  public class Test2 {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        System.out.print("请输入被除数:");
        // 除数为0异常: ArithmeticException
        // 输入格式不正确: InputMismathException(子类)
        try {
            //程序中可能出现异常的代码
            int num1 = in.nextInt();
            System.out.print("请输入除数:");
            int num2 = in.nextInt();
            System.out.println(num1 + "/" + num2 + "=" + num1 / num2);
        } catch (ArithmeticException e) {
            //在程序出现异常的情况下执行的代码
            System.err.print("出现错误操作" + "\n");
            // 异常对象 e printStackTrace();打印异常堆栈信息
            e.printStackTrace();
        } finally {
            System.out.println("感谢使用本程序！");
        }
    }
}

try{
//代码块
}cetch(){
//代码块
}cetch(){
//代码块
}cetch(){
//代码块
}finally{
//代码块
}


public class Test3 {
public static void main(String[] args) {
    Scanner in = new Scanner(System.in);
    System.out.print("请输入被除数:");
    // 除数为0异常: ArithmeticException
    // 输入格式不正确: InputMismatchException(子类)
    try {
        int num1 = in.nextInt();
        System.out.print("请输入除数:");
        int num2 = in.nextInt();
        System.out.println(num1 + "/" + num2 + "=" + num1 / num2);
    } catch (ArithmeticException e) {
        System.err.print("除数不能为0" + "\n");
        // 异常对象 e printStackTrace();打印异常堆栈信息
        e.printStackTrace();
    } catch (InputMismatchException e) {
        System.err.print("输入格式不正确" + "\n");
        e.printStackTrace();
    } catch (Exception e) {
        System.err.print("未知异常" + "\n");
        e.printStackTrace();
    }finally {
        System.out.println("感谢使用本程序！");
    }
}

public void 方法名（）throws 异常类型{
//代码块
}
public static void main(String[] args){
类名 t = new 类名();
try{
t.方法名();
}
}

 public static void a() throws ArithmeticException{
            int num=5/0;
            throw  new ArithmeticException("除数不能为0");
    }
    
    public static void b(){
    try{
        a();
    }catch(ArithmeticException e){
        e.printStackTrace();
    }
    }

public void 方法名（）throws 异常类型{
 //代码块
}
public static void     main(String[] args) throws 异常类型{
类名 t = new 类名();
 t.方法名();
}
    

public static void main(String[] args) {
        try{
            b();
        }catch(ArithmeticException e){
            e.printStackTrace();
        }
    }
    
    public static void a() throws ArithmeticException{
            int num=5/0;
            throw  new ArithmeticException("除数不能为0");
    }
    
    public static void b() throws ArithmeticException{
            a();
    }

public void 方法名（）throws Exception{
           throw new Exception(“性别只能为男女”);
    }
    throw  new ArithmeticException("除数不能为0");

public class LoginFaildException extends Exception {
public LoginFaildException() {
        super();
        
    }

    public LoginFaildException(String message, Throwable cause) {
        super(message, cause);
        
    }

    public LoginFaildException(String message) {
        super(message);
        
    }

    public LoginFaildException(Throwable cause) {
        super(cause);
        
    }

public  class User {
    private String userName;
    private String passWord;
    
    public String getUserName() {
        return userName;
    }
    public void setUserName(String userName) {
        this.userName = userName;
    }
    public String getPassWord() {
        return passWord;
    }
    public void setPassWord(String passWord) {
        this.passWord = passWord;
    }

// 注册方法
        public static boolean register(User user) throws RegisterException {     //声明一个返回值为布尔类型的方法
            boolean flag = false;             //声明返回值变量
            if (user.getUserName() == null) {   
                if (!flag) {
                    throw new RegisterException("用户名不能为空，注册失败");    //抛出注册异常
                } else {
                    return true;
                }
            }else if(user.getPassWord().equals(null)){
                return false;
            }
            return true;
        }

// 登录方法
    public static void login(User user) throws LoginFaildException {  
        try {
             boolean register= register(user);    
            
        } catch (RegisterException e) {
            e.printStackTrace();
            throw new LoginFaildException("登录失败",e);    //核心代码，将注册与登录异常抛给登录异常构造方法
        }

    }

public static void main(String[] args) {
        User user = new User();
        try {
            login(user);
        } catch (LoginFaildException e) {
            e.printStackTrace();      //抛出异常
    }

exception.RegisterException: 用户名不能为空，注册失败
    at test.Test4.register(Test4.java:23)
    at test.Test4.login(Test4.java:36)
    at test.Test4.main(Test4.java:12)
exception.LoginFaildException: 登录失败
    at test.Test4.login(Test4.java:40)
    at test.Test4.main(Test4.java:12)
Caused by: exception.RegisterException: 用户名不能为空，注册失败
    at test.Test4.register(Test4.java:23)
    at test.Test4.login(Test4.java:36)
    ... 1 more