java - throwable 不会编译

Question

首先我必须说我阅读了以下内容： http: //docs.oracle.com/javase/tutorial/essential/exceptions/index.html！

我尝试编译时得到的错误如下：

TestException.java:14: error: incompatible types

static void doRisky(String test) throws ScaryException
                                                ^
required: Throwable
found:    ScaryException

TestException.java:19: error: incompatible types
                        throw new ScaryException();
                                      ^
required: Throwable
found:    ScaryException

TestException.java:34: error: incompatible types
                catch ( ScaryException  se)
                        ^
  required: Throwable
  found:    ScaryException

3 errors

我假设错误消息给了我某种类型的提示，但我只是不明白它是什么。

import java.lang.*;
/** add this as to get it to compile */
class ScaryException extends Exception
{
/** how come I can't put code here? */
}

public class  TestException {

    static void doRisky(String test) throws ScaryException{
        System.out.println ("start risky");    
        if ("yes".equals(test)) {
            throw new ScaryException();
        }
        System.out.println("end risky");
    }

    public static void main(String [] args){
        String test = "no";
        try{
            System.out.println("start try");
            doRisky(test);
            doRisky("yes");
            System.out.println("end try");
        }
        catch ( ScaryException  se){
            System.out.println("Got What " + se);
        }
        finally{
            System. out. println( "finally") ;
        }

        System.out.println("end of main");
    }
}

Answer 1

Java 异常必须扩展Throwable（直接扩展，或者最好通过扩展Exception或其子类之一间接扩展）。显然你的ScaryException班级没有。

Answer 2

要编译，ScaryException必须是扩展的类Throwable或其子类之一。要么ScaryException根本不存在，要么不扩展任何Throwable' 子级。