JAVA学习--异常Exception的处理

  1 import java.io.File;
  2 import java.io.FileInputStream;
  3 import java.io.FileNotFoundException;
  4 import java.io.IOException;
  5 import java.util.Date;
  6 import java.util.InputMismatchException;
  7 import java.util.Scanner;
  8 
  9 import org.junit.Test;
 10 
 11 
 12 public class TestException1 {
 13     // 编译时异常
 14     @Test
 15     public void test6() {
 16         FileInputStream fis = null;
 17         try {
 18             fis = new FileInputStream(new File("hello.txt"));
 19             int b;
 20             while ((b = fis.read()) != -1) {
 21                 System.out.print((char) b);
 22             }
 23 
 24         } catch (FileNotFoundException e1) {
 25             System.out.println("文件找不到了！");
 26         } catch (IOException e1) {
 27             System.out.println(e1.getMessage());
 28         } finally {
 29             try {
 30                 fis.close();
 31             } catch (IOException e) {
 32                 // TODO Auto-generated catch block
 33                 e.printStackTrace();
 34             }
 35         }
 36     }
 37 
 38     // 常见的运行时异常
 39     // 4.空指针异常：NullPointerExcetion
 40     @Test
 41     public void test5() {
 42         // Person p = new Person();
 43         // p = null;
 44         // System.out.println(p.toString());
 45 
 46         try {
 47             String str = new String("AA");
 48             str = null;
 49             System.out.println(str.length());
 50         } catch (Exception e) {
 51             // e.printStackTrace();
 52             System.out.println("出现空指针的异常了");
 53         }
 54     }
 55 
 56     // 3.类型转换异常：ClassCastException
 57     @Test
 58     public void test4() {
 59         try {
 60             Object obj = new Date();
 61             String str = (String) obj;
 62         } catch (ClassCastException e) {
 63             System.out.println("出现类型转换的异常了");
 64             //System.out.println(10 / 0);
 65         } catch (Exception e) {
 66             e.printStackTrace();
 67         } finally {
 68             System.out.println("hello!美女！");
 69         }
 70         // String str1 = (String)new Date();
 71     }
 72 
 73     // 2.算术异常：ArithmeticException
 74     @Test
 75     public void test3() {
 76         try {
 77             int i = 10;
 78             System.out.println(i / 0);
 79         } catch (Exception e) {
 80             // e.printStackTrace();
 81             System.out.println(e.getMessage());
 82         }
 83     }
 84 
 85     // 1.数组下标越界的异常:ArrayIndexOutOfBoundsException
 86     @Test
 87     public void test2() {
 88         try {
 89             int[] i = new int[10];
 90             // System.out.println(i[10]);
 91             System.out.println(i[-10]);
 92         } catch (Exception e) {
 93             System.out.println("出现异常了！");
 94         }
 95     }
 96 
 97     @Test
 98     public void test1() {
 99         Scanner s = new Scanner(System.in);
100         try {
101             int i = s.nextInt();
102             System.out.println(i);
103         } catch (InputMismatchException e) {
104             System.out.println("出现类型不匹配的异常了！");
105         }
106     }
107 }