异常

异常介绍

异常体系

一定要能阐述异常的体系结构！
异常类的祖先类：Throwable
所有的异常都是一个类，如果不清楚可以在API帮助文档查询

运行时异常：编译时没有错误，运行时可能会出错，通常是代码不严谨导致的
编译时异常（不包含语法错误）：主要起提醒作用，需要在运行之前给出解决方式

异常处理方式

异常的默认处理流程

异常处理方式的选择

方式1：try catch捕获异常

方式2：throws抛出异常

throw和throws的区别

Student.java

package com.EveX.domain;

public class Student {
    String name;
    int age;

    public Student() {
    }

    public Student(String name, int age) {
        this.name = name;
        this.age = age;
    }

    /**
     * 获取
     * @return name
     */
    public String getName() {
        return name;
    }

    /**
     * 设置
     * @param name
     */
    public void setName(String name) {
        this.name = name;
    }

    /**
     * 获取
     * @return age
     */
    public int getAge() {
        return age;
    }

    /**
     * 设置
     * @param age
     */
    public void setAge(int age) throws Exception {
        if(age > 120 || age < 0) {
            throw new Exception("输入年龄范围有误，请重新输入");
        }
        this.age = age;
    }

    public String toString() {
        return "Student{name = " + name + ", age = " + age + "}";
    }
}

ExceptionDemo.java

package com.EveX.exception.handle;

import com.EveX.domain.Student;

import java.util.Scanner;

public class ExceptionDemo {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);

        Student stu = new Student();
        System.out.println("请输入姓名：");
        String name = in.nextLine();
        stu.setName(name);
        System.out.println("请输入年龄：");
        int age = 0;

        while (true) {
            try {
                age = Integer.parseInt(in.nextLine());
                stu.setAge(age);
                break;
            } catch (NumberFormatException e) {
                System.out.println("NumberFormatException，请重新输入整数：");
            } catch (Exception e) {
                System.out.println(e.getMessage());
            }
        }


        System.out.println(stu);

    }
}

自定义异常

StudentAgeException.java

package com.EveX.exception;

public class StudentAgeException extends RuntimeException{
    public StudentAgeException() {
    }

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

Student.java

package com.EveX.domain;

import com.EveX.exception.StudentAgeException;

public class Student {
    String name;
    int age;

    public Student() {
    }

    public Student(String name, int age) {
        this.name = name;
        setAge(age);
    }

    /**
     * 获取
     * @return name
     */
    public String getName() {
        return name;
    }

    /**
     * 设置
     * @param name
     */
    public void setName(String name) {
        this.name = name;
    }

    /**
     * 获取
     * @return age
     */
    public int getAge() {
        return age;
    }

    /**
     * 设置
     * @param age
     */
    public void setAge(int age) throws StudentAgeException {
        if(age > 120 || age < 0) {
            throw new StudentAgeException("输入年龄范围有误，请重新输入");
        }
        this.age = age;
    }

    public String toString() {
        return "Student{name = " + name + ", age = " + age + "}";
    }
}

TryCatchDemo.java

package com.EveX.exception.handle;

import com.EveX.domain.Student;
import com.EveX.exception.StudentAgeException;

import java.util.Scanner;

public class TryCatchDemo {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);

        Student stu = new Student();
        System.out.println("请输入姓名：");
        String name = in.nextLine();
        stu.setName(name);
        System.out.println("请输入年龄：");
        int age = 0;

        while (true) {
            try {
                age = Integer.parseInt(in.nextLine());
                stu.setAge(age);
                break;
            } catch (NumberFormatException e) {
                System.out.println("NumberFormatException，请重新输入整数：");
            } catch (StudentAgeException e) {
                System.out.println(e.getMessage());
            }
        }

        System.out.println(stu);

    }
}