3.throws throw try-catch-finally 自定义异常类

import java.io.*;

public class ExceptionTest {
    /**
     * 参考：https://blog.csdn.net/qq_29229567/article/details/80773970
     * Error(错误) VS Exception(异常)
     * Exception分为：运行时异常(RuntimeException) VS 非运行时异常(非RuntimeException)
     * 可查异常(Exception下非RuntimeException) VS 不可查异常/错误(RuntimeException+Error)
     * Java规定，对于可查异常必须捕捉、或者声明抛出，允许忽略不可查异常/错误
     * NoClassDefFoundError类定义错误(属于Error) VS ClassNotFoundException类找不到异常(属于Exception)
     * throws throw try-catch-finally 如何使用？
     * 如何自定义异常类？
     */

    public static void main(String[] args) {
        ArithmeticExceptionTest(0);
        FileNotFoundExceptionANDIOExceptionTest("E://test.txt");
        try {
            ThrowsTest("E://test.txt");
        } catch (IOException e) {
            e.printStackTrace();
        }
        ThrowTest(5);
        SelfDefExceptionTest(5);
    }
    
    // 属于RuntimeException (执行时才会报出异常)
    public static void ArithmeticExceptionTest(int i) {
        System.out.println(10 / i);
    }

    // 非RuntimeException=可查异常(编译器要求必须处置的异常)
    public static void FileNotFoundExceptionANDIOExceptionTest(String filename) {
        try {
            BufferedReader in = new BufferedReader(new FileReader(filename));
            String str;
            while ((str = in.readLine()) != null) {
                System.out.println(str);
            }
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    // throws在方法上外抛异常,上面处理异常或者再往上面throws异常,main方法可以抛出异常。
    private static void ThrowsTest(String filename) throws IOException {
        BufferedReader in = new BufferedReader(new FileReader(filename));
        String str;
        while ((str = in.readLine()) != null) {
            System.out.println(str);
        }
    }

    // throw(try代码块中自定义抛出什么异常)
    private static void ThrowTest(int a) {
        try {
            if (10 > a) {
                throw new Exception("对不起,您输入的值不能小于10!");
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            System.out.println("finally 除开一些特例一定都会执行的！\n" +
                    "     1）在finally语句块中发生了异常。\n" +
                    "     2）在前面的代码中用了System.exit()退出程序。\n" +
                    "     3）程序所在的线程死亡。\n" +
                    "     4）关闭CPU。");
        }

    }

    // 抛出自定义异常,捕获自定义异常类MyException
    private static void SelfDefExceptionTest(int a) {
        try {
            if (10 > a) {
                throw new MyException("对不起,您输入的值不能小于10!");
            }
        } catch (MyException e) {
            e.printStackTrace();
        }
    }
}

// 自定义MyException类
class MyException extends Exception {
    public MyException(String msg) {
        super(msg);
    }
}