JavaEE开发重中之重 异常 捕获并抛出异常 自定义异常 2024详解

public class Main {
    public static void main(String[] args) {
        int arr[]=new int[]{1,2,3,4,5};
        try {
            System.out.println(arr[5]);
            //可能出现异常的代码
        }catch (ArrayIndexOutOfBoundsException e){
            System.out.println("数组越界");
            //出现异常后的处理
        }
        System.out.println("执行完毕");
    }
}

public class Main {
    public static void main(String[] args) {
        int arr[]=new int[]{1,2,3,4,5};
        try {
            System.out.println(arr[5]);
            System.out.println("未出现异常");
        }catch (ArrayIndexOutOfBoundsException e){
            e.printStackTrace();
            System.out.println("数组越界");
        }
        System.out.println("执行完毕");
    }
}

System.err.println("执行完毕");//打印错误信息(红色字体)

public class Main {
    public static void main(String[] args) {
        int arr[]=null;
        System.out.println(getMax(arr));
    }
    public static int getMax(int arr[]){
        int max=0;
        if(arr==null)
            //手动创建一个异常对象，并把这个异常交给方法调用者去处理
            //此时方法就会结束，下面的代码就不会再执行了
            throw new NullPointerException();
        for(int i :arr)
            if (i>max)
                max=i;
        return max;
    }
 
}

public class Student {
    private String name;
    private int age;
 
    public Student() {
    }
 
    public Student(String str) {
        //str依次表示流里面的每个数据
        //形参要和抽象方法形参一致
        String arr[]=str.split(",");
        this.name=arr[0];
        this.age=Integer.parseInt(arr[1]);
    }
 
    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) {
        this.age = age;
    }
 
    public  String toString() {
        return  name + "-" + age ;
    }
}

import java.util.Scanner;
 
public class Main {
    public static void main(String[] args) {
        Scanner sc=new Scanner(System.in);
        Friend f=new Friend();
        while(true){
            try {
                System.out.println("请录入名称");
                String name=sc.next();
                f.setName(name);
                System.out.println("请录入年龄");
                int age=sc.nextInt();
                f.setAge(age);
                //如果捕获到了异常，会进入catch()
                //如果所有数据都正确，那么会跳出循环
                break;
            } catch (RuntimeException e) {
                System.out.println("输入的年龄不符合规范,请重新输入");
            }
        }
        System.out.println(f);
    }
}

public class NameformatException extends RuntimeException{
    public NameformatException() {
    }
 
    public NameformatException(String message) {
        super(message);
    }
}

import java.util.Scanner;
 
public class Main {
    public static void main(String[] args) {
        Scanner sc=new Scanner(System.in);
        Friend f=new Friend();
        while(true){
            try {
                System.out.println("请录入名称");
                String name=sc.next();
                f.setName(name);
                System.out.println("请录入年龄");
                int age=sc.nextInt();
                f.setAge(age);
                //如果捕获到了异常，会进入catch()
                //如果所有数据都正确，那么会跳出循环
                break;
            } catch (NameformatException e) {
                e.printStackTrace();
                System.out.println("输入的年龄不符合规范,请重新输入");
            }
        }
        System.out.println(f);
    }
}

public class Friend {
    private String name;
    private int age;
 
    public Friend() {
    }
 
    public Friend(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;
        if(name.length()>3)
            throw new NameformatException("名称长度不符合规范");
    }
 
    /**
     * 获取
     * @return age
     */
    public int getAge() {
        return age;
    }
 
    /**
     * 设置
     * @param age
     */
    public void setAge(int age) {
        this.age = age;
    }
 
    public String toString() {
        return "Friend{name = " + name + ", age = " + age + "}";
    }
}