动手动脑10.16

多层tyr-catch嵌套来挂测其先后顺序：

public class CatchWho { 
    public static void main(String[] args) { 
        try { 
            	try { 
                	throw new ArrayIndexOutOfBoundsException(); 
            	} 
            	catch(ArrayIndexOutOfBoundsException e) { 
               		System.out.println(  "ArrayIndexOutOfBoundsException" +  "/内层try-catch"); 
            	}
 
            throw new ArithmeticException(); 
        } 
        catch(ArithmeticException e) { 
            System.out.println("发生ArithmeticException"); 
        } 
        catch(ArrayIndexOutOfBoundsException e) { 
           System.out.println(  "ArrayIndexOutOfBoundsException" + "/外层try-catch"); 
        } 
    } 
}

public class CatchWho2 {
    public static void main(String[] args) {
        try {
            try {
                throw new ArrayIndexOutOfBoundsException();
            } catch (ArithmeticException e) {
                System.out.println("ArrayIndexOutOfBoundsException" + "try-catch");
            }
            throw new ArithmeticException();
        } catch (ArithmeticException e) {
            System.out.println("·¢ÉúArithmeticException");
        } catch (ArrayIndexOutOfBoundsException e) {
            System.out.println("ArrayIndexOutOfBoundsException" + "2132123aaatry-catch");
        }
    }
}

上面是同样道理

观测异常处理，catch抓取几个异常

import java.io.*;

public class CheckedExceptionDemo {
    public static void main(String[] args) {
        try {
            BufferedReader buf = new BufferedReader(
                    new InputStreamReader(System.in)); // 抛出受控的异常
            System.out.print("请输入整数: ");
            int input = Integer.parseInt(buf.readLine()); // 有可能引发运行时异常
            System.out.println("input x 10 = " + (input * 10));
        }
        // 以下异常处理语句块是必须的，否则无法通过编译
        catch (IOException e) {
            System.out.println("I/O错误");
        }
        // 以下异常处理语句块可以省略，不影响编译，但在运行时出错
        catch (NumberFormatException e) {
            System.out.println("输入必须为整数");
        }
    }
}

查看try-catch先后嵌套顺序

public class EmbededFinally {

	public static void main(String args[]) {

		int result;

		try {

			System.out.println("in Level 1");

			try {

				System.out.println("in Level 2");
				// result=100/0; //Level 2

				try {

					System.out.println("in Level 3");

					result = 100 / 0; // Level 3

				}

				catch (Exception e) {

					System.out.println("Level 3:" + e.getClass().toString());

				}

				finally {

					System.out.println("In Level 3 finally");

				}

				// result=100/0; //Level 2

			}

			catch (Exception e) {

				System.out.println("Level 2:" + e.getClass().toString());

			} finally {

				System.out.println("In Level 2 finally");

			}

			// result = 100 / 0; //level 1

		}

		catch (Exception e) {

			System.out.println("Level 1:" + e.getClass().toString());

		}

		finally {

			System.out.println("In Level 1 finally");

		}

	}

}

浮点数除以0是infinity，不是异常

public class ThrowDemo { 
    public static void main(String[] args) { 
//        try {
            double data = 100 / 0.0;
            System.out.println("浮点数除以零：" + data); 
//            if(String.valueOf(data).equals("Infinity"))
//            { 
//            	System.out.println("In Here" ); 
//                throw new ArithmeticException("除零异常");
//            }
//        } 
//        catch(ArithmeticException e) { 
//            System.out.println(e); 
//        } 
    } 
	
	```
	![image](https://img2023.cnblogs.com/blog/2973495/202310/2973495-20231016225007019-1437710534.png)

import java.io.*;

public class ThrowMultiExceptionsDemo {
public static void main(String[] args) {
try {
throwsTest();
} catch (IOException e) {
System.out.println("捕捉异常");
}
}

private static void throwsTest() throws ArithmeticException, IOException {
    System.out.println("这只是一个测试");
    // 程序处理过程假设发生异常
    throw new IOException();
    // throw new ArithmeticException();
}

}