Java BufferedReader在循环之前检查循环的下几行

问题描述

我正在解析.cvs文件.对于cvs的每一行，我都会创建一个具有解析值的对象，并将它们放入集合中.

I'm parsing a .cvs file.For each line of the cvs, I create an object with the parsed values, and put them into a set.

在将对象放入地图并循环到下一个对象之前，我需要检查下一个cvs的行是否与实际对象相同，但特定属性值不同.

Before putting the object in the map and looping to the next, I need to check if the next cvs's line is the same object as the actual, but with a particular property value different.

为此，我需要检查缓冲区的下几行，但将循环缓冲区保持在相同位置.

For that, I need check the next lines of the buffer, but keep the loop's buffer in the same position.

例如:

BufferedReader input  = new BufferedReader(new InputStreamReader(new FileInputStream(file),"ISO-8859-1"));
String line = null;

while ((line = input.readLine()) != null) {
    do something

    while ((nextline = input.readLine()) != null) { //now I have to check the next lines
       //I do something with the next lines. and then break.
    }
    do something else and continue the first loop.
}

推荐答案

1. 您可以使用 BufferedReader.mark(int) .要返回到该位置，请调用BufferedReader.reset(). mark的参数是预读限制"；如果您尝试读取的内容超过了限制，而又尝试reset()，则可能会得到IOException.

1. You can mark the current position using BufferedReader.mark(int). To return to the position you call BufferedReader.reset(). The parameter to mark is the "read ahead limit"; if you try to reset() after reading more than the limit you may get an IOException.

或者您可以使用 RandomAccessFile 代替:

Or you could use RandomAccessFile instead:

// Get current position
long pos = raf.getFilePointer();
// read more lines...
// Return to old position
raf.seek(pos);

或者您可以使用 PushbackReader ，您可以输入unread个字符.但是有一个缺点:PushbackReader不提供readLine方法.

Or you could use PushbackReader which allows you to unread characters. But there's the drawback: PushbackReader does not provide a readLine method.

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