从文件中读取可变数量的行

Question

I am trying to read a variable number of lines from a file, hopefully using InputStream object. What I'm trying to do (in a very general sense) is as follows:

Pass in long maxLines to function
Open InputStream and OutputStream for reading/writing
WHILE (not at the end of read file AND linesWritten < maxLines)
   write to file

I know InputStream goes on bytes, not lines, so I'm not sure if that's a good API to use for this. If anyone has any reccomendations on what to look at in terms of a solution (other API's, different algorithm) that's be very helpful.

Answer 1

You can have something like this

       BufferedReader br = new BufferedReader(new FileReader("FILE_LOCATION"));
       while (br.readLine() != null && linesWritten < maxLines) { 
         //Your logic goes here
        }

Answer 2

Have a look at these:

Buffered Reader and Buffered Writer

//Read file into String allText
InputSream fis = new FileInputStream("filein.txt");
BufferedReader br = new BufferedReader(new InputStreamReader(fis));
String line, allText = "";
try {
    while ((line = br.readLine()) != null) {
        allText += (line + System.getProperty("line.separator")); //Track where new lines should be for output
    }
} catch(IOException e) {} //Catch any errors
br.close(); //Close reader

//Write allText to new file
BufferedWriter bw = new BufferedWriter(new FileWriter("fileout.txt"));
try {
    bw.write(allText);
} catch(IOException e) {} //Catch any errors
bw.close(); //Close writer