Java Exception create your own Exception Subclasses

Introduction

The following code creates a new subclass of Exception.

It then uses that subclass to signal an error condition in a method.

It overrides the toString() method to provide a description of the exception. 

class MyException extends Exception {  
  private int detail;  
  
  public MyException(int a) {  
    detail = a;  /*from  w w  w  . j  a v  a  2 s. com*/
  }  
  
  public String toString() {  
    return "MyException[ value is " + detail + "]";  
  }  
}  
  
public class Main {  
  static void compute(int a) throws MyException {  
    throw new MyException(a);  
  }  
  
  public static void main(String args[]) {  
    try {  
      compute(1);  
      compute(20);  
    } catch (MyException e) {  
      System.out.println("Caught " + e);  
    }  
  }  
} 

public class Main {
   static Object chatServer = null;

   public static void main(String[] args) {
      try {/* w ww  . ja va  2  s.com*/
         sendChat("Hello, how are you?");
      } catch (ConnectionUnavailableException e) {
         System.out.println("Got a connection unavailable Exception!");
      }

      disconnectChatServer(chatServer);
   }

   private static void disconnectChatServer(Object chatServer) {
      if (chatServer == null)
         throw new IllegalChatServerException("Chat server is empty");
   }

   private static void sendChat(String chatMessage) throws ConnectionUnavailableException {
      if (chatServer == null)
         throw new ConnectionUnavailableException("Can't find the chat server");
   }

}

class ConnectionUnavailableException extends Exception {
   ConnectionUnavailableException(String message) {
      super(message);
   }
}

class IllegalChatServerException extends RuntimeException {
   IllegalChatServerException(String message) {
      super(message);
   }
}



PreviousNext

Related