try 和 finally 给出没有返回语句的异常，但是在方法中写入返回语句时没有异常 [英] try and Finally giving exception with no return statement , but there is no exception when return statement is written in method

问题描述

请解释为什么异常出现在第一个程序中，但没有出现在第二个程序中.

Please explain why Exception comes in first program but not in second program.

1) read 方法中没有返回语句

1) without return statement in read method

class Example
{   
    public static void read()
    {
        try
        {
             int i = 9/0;
        }
        finally
        {
              System.out.println("This proogram is giving exception");
        }       
    }

    public static void main(String[] fel)
    {
         read();
    }
}

2)read方法中带有return语句

2)with return statement in read method

class Example
{   
    public static void read()
    {
         try
         {
               int i = 9/0;
         }
        finally
        {
               System.out.println("This proogram is not giving exception");
               return;
        }       
    }

    public static void main(String[] fel)
    {
          read();
    }
}

推荐答案

分支语句(return ,goto )不能在finally内部使用，因为执行这样的语句会使finally之前执行的其他指令无效.

Branching statements(return ,goto ) should no be used inside finally because execution of such statement nullifies other instructions which are executed before finally.

Java 语言规范 说:如果 try 块的执行由于任何其他原因 R 突然完成，则执行 finally 块，然后有一个选择:

The Java Language Specification says : If execution of the try block completes abruptly for any other reason R, then the finally block is executed, and then there is a choice:

1. 如果 finally 块正常完成，则由于原因 R，try 语句会突然完成.
2. 如果 finally 块由于原因 S 突然完成，则 try 语句由于原因 S 突然完成(并且原因 R 被丢弃).

注意 - finally 块中的 return 语句将导致 try 或 catch 块中可能引发的任何异常被丢弃.

Note - A return statement inside a finally block will cause any exception that might be thrown in the try or catch block to be discarded.

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