Java StringReader读取超出输入。(Java StringReader reads beyond input. Is this a bug or expected behavior? [

Java StringReader读取超出输入。(Java StringReader reads beyond input. Is this a bug or expected behavior? [closed])

试试这个代码 -

import java.io.StringReader; public class StringReaderTest { public static void main(String[] args) throws Exception { String sampleString = "abcdefg"; StringReader reader = new StringReader(sampleString); for(int i=0; i<40; i++) { char c = (char) reader.read(); System.out.print(c); } } }

输出是 -

abcdefg?????????????????????????????????

所以读者实际上已经阅读了输入的结尾。 我的印象是，当它试图超越“g”时应该抛出一个例外，但事实并非如此。 它反而返回一个“？” 字符。 这是一个错误还是这种预期的行为？

Try this code -

import java.io.StringReader; public class StringReaderTest { public static void main(String[] args) throws Exception { String sampleString = "abcdefg"; StringReader reader = new StringReader(sampleString); for(int i=0; i<40; i++) { char c = (char) reader.read(); System.out.print(c); } } }

The output is -

abcdefg?????????????????????????????????

So the reader actually read past the end of the input. I was under the impression that it should have thrown an exception when it tried to read beyond "g", but it did not. It instead returned a "?" character. Is this a bug or is this expected behavior?

最满意答案

这种情况下的文档很清楚：

StringReader.read()

返回：读取的字符，如果已到达流的末尾，则返回 -1

The documentation is quite clear in this case:

StringReader.read()

Returns: The character read, or -1 if the end of the stream has been reached