异常体系结构

 

 

/*
* 一、异常体系结构
*
* java.lang.Throwable
* |-----java.lang.Error:一般不编写针对性的代码进行处理。
* |-----java.lang.Exception:可以进行异常的处理
* |------编译时异常(checked)
* |-----IOException
* |-----FileNotFoundException
* |-----ClassNotFoundException
* |------运行时异常(unchecked,RuntimeException)
* |-----NullPointerException
* |-----ArrayIndexOutOfBoundsException
* |-----ClassCastException
* |-----NumberFormatException
* |-----InputMismatchException
* |-----ArithmeticException
*
*
*
* 面试题：常见的异常都有哪些？举例说明
*/

public class ExceptionTest {
    
    //******************以下是编译时异常***************************
    @Test
    public void test7(){
//        File file = new File("hello.txt");
//        FileInputStream fis = new FileInputStream(file);
//        
//        int data = fis.read();
//        while(data != -1){
//            System.out.print((char)data);
//            data = fis.read();
//        }
//        
//        fis.close();
        
    }
    
    //******************以下是运行时异常***************************
    //ArithmeticException算数异常
    @Test
    public void test6(){
        int a = 10;
        int b = 0;
        System.out.println(a / b);
    }
    
    //InputMismatchException输入类型错误异常 
    @Test
    public void test5(){
        Scanner scanner = new Scanner(System.in);
        int score = scanner.nextInt();
        System.out.println(score);
        
        scanner.close();
    }
    
    //NumberFormatException字符串转成数值类型时的异常
    @Test
    public void test4(){
        
        String str = "123";
        str = "abc";
        int num = Integer.parseInt(str);
        
        
        
    }
    
    //ClassCastException类型转换异常
    @Test
    public void test3(){
        Object obj = new Date();
        String str = (String)obj;
    }
    
    //IndexOutOfBoundsException数组角标越界
    @Test
    public void test2(){
        //ArrayIndexOutOfBoundsException
//        int[] arr = new int[10];
//        System.out.println(arr[10]);
        //StringIndexOutOfBoundsException
        String str = "abc";
        System.out.println(str.charAt(3));
    }
    
    //NullPointerException空指针异常
    @Test
    public void test1(){
        
//        int[] arr = null;
//        System.out.println(arr[3]);
        
        String str = "abc";
        str = null;
        System.out.println(str.charAt(0));
        
    }
    
    
}