The readline method, however, reads the specified number of characters and continues reading until the end of that line.

但是readline方法在读入指定数量的字符后，还会继续读取，直到行尾。

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This method returns -1 if it reaches the end of the input stream before reading the maximum number of bytes.

如果在读入最大数量的字节前，抵达输入流结尾，方法返回- 1。

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