Java之常见异常

package com.atguigu.java1;

import java.io.File;
import java.io.FileInputStream;
import java.util.Date;
import java.util.Scanner;

import org.junit.Test;

/*
 * 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
   @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));

   }

}