每天一点点java---继承exception类来实现自己的异常类

package prac_1;

/**
* <p>Title: 捕获异常和实现自己的异常类</p>
* <p>Description: 通过继承Exception类来实现自己的异常类。并使用try－catch来捕获这个异常。</p>
* <p>Copyright: Copyright (c) 2014</p>
* <p>Filename: </p>
* @author 王海涛
* @version 0.1
*/
class MyException extends Exception {
public MyException() {}
public MyException(String msg) {
super(msg);
}
public MyException(String msg, int x) {
super(msg);
i = x;
}
public int val() { return i; }
private int i;
}

public class ExceptionDemo {
/**
*<br>方法说明：使用MyException类中默认的构造器
*/
public static void a() throws MyException {
System.out.println(
"Throwing MyException from a()");
throw new MyException();//抛出异常，结束方法
}
/**
*<br>方法说明：使用MyException类中带信息的构造器
*/
public static void b() throws MyException {
System.out.println(
"Throwing MyException from b()");
throw new MyException("error in b ()");
}
/**
*<br>方法说明：使用了MyException中有编码的构造器
*/
public static void c() throws MyException {
System.out.println(
"Throwing MyException from c()");
throw new MyException(
"error in c()", 404);
}
public static void main(String[] args) {
try {
a();
} catch(MyException e) {
System.out.println( "Error="+e.getMessage());
}
try {
b();
} catch(MyException e) {
System.out.println( "Error="+e.getMessage());
//e.toString();
}
try {
c();
} catch(MyException e) {
System.out.println( "Error="+e.getMessage());
e.printStackTrace();
System.out.println("error code: " + e.val());
}
}
} //end :)