声明异常、抛出异常

异常处理
package com.softeem.len11;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.net.SocketException;
public class Test {
                                  //申明此方法有可能会抛出一个空指针异常
    public void show(String param) throws SocketException , IOException ,Exception{
        int number=param.length();//得到字符串长度
        System.out.println("字符串长度"+number);
    }                           //申明泡池一个已检查异常（文件没找到）
    public void readFile(String filePath)throws FileNotFoundException {    
    }
    public void tets()throws FileNotFoundException{
        this.readFile("c:/123.txt");
    }
    //throws--声明异常           throw-----抛出异常对象
    public void test2(int i,int j)throws ArithmeticException{//运行时异常
        if (j==0) {
            ArithmeticException ex=new ArithmeticException("除数不能为零");
            throw ex;//抛出异常对象
        }
        int x=i/j;
        System.out.println("结果:"+x);
    }
    public static void main(String[] args){
        Test t=new Test();
            try {
                t.tets();
                t.show(null);//方法调用
                t.readFile("c:/123.txt");//方法调用
            } catch (FileNotFoundException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch (Exception e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
                t.test2(4, 0);
//        FileInputStream in=new FileInputStream("c:123.txt");    
    }
}