day20 异常1

* 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

 

//******************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
@Test
public void test6(){
int a = 10;
int b = 0;
System.out.println(a / b);
}

//InputMismatchException
@Test
public void test5(){
Scanner scanner = new Scanner(System.in);
int score = scanner.nextInt();
System.out.println(score);

scanner.close();
}

//NumberFormatException
@Test
public void test4(){

String str = "123";
str = "abc";
int num = Integer.parseInt(str);



}

//ClassCastException
@Test
public void test3(){
Object obj = new Date();
String str = (String)obj;
}

//IndexOutOfBoundsException
@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
@Test
public void test1(){

// int[] arr = null;
// System.out.println(arr[3]);

String str = "abc";
str = null;
System.out.println(str.charAt(0));

}