Question

Hello World！，我有一个关于Input Stream类的close（）方法的问题。这是我的代码 - ＆gt;

public class Main{
    InputStream consoleInputStream = System.in;
    byte[] bytes = new byte[2];

    consoleInputStream.read(bytes); // I gave the input --> abcdefghij and then enter key(line feed). 
                                    // Hence, abcdefghij and line feed(ASCII - 10) have all entered into consoleInputStream object. 
                                    // The first two bytes i.e. a and b have entered into bytes array.

    for(int i = 0; i < bytes.length; i++){
        System.out.print((char)bytes[i]); // it should print ab
    }

    consoleInputStream.skip(2); // should skip the next two bytes i.e. cd

    consoleInputStream.close(); // closes the connection with console.
                                // I am drawing analogy with the fileInputStream close()

    consoleInputStream.read(bytes); // should read the next two bytes from the consoleInputStream object i.e. e and f, and store them in bytes array.
                                    // Although the stream is closed i.e. connection with the console is closed but the stream already has these characters.

     for(int i = 0; i < bytes.length; i++){
        System.out.print((char)bytes[i]); // should print ef
    }
}

逐行我写了我认为应该发生的事情。但是程序在运行时引发异常如下 - ＆gt;

java.io.IOException: Stream closed

当我最初通过控制台输入 abcdefghij 时，所有这些字符都会进入consoleInputStream对象。我觉得应该是什么。这是因为skip（）方法工作正常，即它跳过接下来的两个字节。因此，consoleInputStream对象必须包含所有字符。

但如果发生这种情况，为什么在关闭后尝试从consoleInputStream对象中读取内容时会出现异常。如果流中已经包含这些字符，那么与控制台的连接是否关闭并不重要。

我刚开始使用溪流，我想在概念上很强大。谁能解释一下究竟发生了什么？我在概念上哪里错了？

Answer 1

您需要先阅读javadoc。 InputStream表示在大多数情况下与基础系统相关的内容的连接，在关闭流后，释放与此流关联的任何系统rosource，并且在调用该方法后此对象仍然无效。

InputStream类

1 个答案: