JAVA学习--异常Exception

import java.io.File;
import java.io.FileInputStream;
import java.util.Date;
import java.util.Scanner;
import org.junit.Test;
public class TestException {
    //编译时异常
    @Test
    public void test6(){
//        FileInputStream fis = new FileInputStream(new File("hello.txt"));
//        int b;
//        while((b = fis.read()) != -1){
//            System.out.println((char)b);
//        }
//        fis.close();
    }
    
    //常见的运行时异常
    
    //4.空指针异常：NullPointerExcetion
    @Test
    public void test5(){
//        Person p = new Person();
//        p = null;
//        System.out.println(p.toString());
        
        String str = new String("AA");
        str = null;
        System.out.println(str.length());
    }
    
    //3.类型转换异常：ClassCastException
    @Test
    public void test4(){
        Object obj = new Date();
        String str = (String)obj;
        
        //String str1 = (String)new Date();
    }
    
    //2.算术异常：ArithmeticException
    @Test
    public void test3(){
        int i = 10;
        System.out.println(i / 0);
    }
    
    //1.数组下标越界的异常:ArrayIndexOutOfBoundsException
    @Test
    public void test2(){
        int[] i = new int[10];
        //System.out.println(i[10]);
        System.out.println(i[-10]);
    }
    
    @Test
    public void test1(){
        Scanner s = new Scanner(System.in);
        int i = s.nextInt();
        System.out.println(i);
    }
}
class Person{
    
}