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

class MyException extends Exception {
	private static final long serialVersionUID = 1L;
 
	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 DemoException {
	/**
	 *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();
	}
 
	/**
	 *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("Originated in b()");
	}
 
	/**
	 *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("Originated in c()", 47);
	}
 
	public static void main(String[] args) {
		try {
			a();
		} catch (MyException e) {
			e.getMessage();
		}
		try {
			b();
		} catch (MyException e) {
			e.toString();
		}
		try {
			c();
		} catch (MyException e) {
			e.printStackTrace();
			System.out.println("error code: " + e.val());
		}
	}
} // end :)