类Exception的默认构造函数？

Question

package com.psl.exception;

public class NoDataFoundException extends Exception {

    public NoDataFoundException(){
        super("No Data Found");
    }

    public NoDataFoundException(String msg){
        super(msg);
    }
}

What does the class Exception do with the string that is passed? I tried it and it does nothing. What is the point of passing the string to the constructor of Exception then?

Answer 1

它在Throwable设置作为消息传递的String ，这通常是有用的自定义消息，当引发异常时会打印该消息，也可以通过Throwable上的getMessage()方法进行检索

Answer 2

The documentation says:

Constructs a new exception with the specified detail message.

The detail message is available from getMessage and usually included in toString and such.

Answer 3

One of the constructors of Exception takes a string to use as the detail message.

See here: http://docs.oracle.com/javase/7/docs/api/java/lang/Exception.html

The default constructor uses a null detail message, but other components such as a message and throwable can be specified