Java-当我使用PrintWriter，BufferedWriter和FileWriter进行写入时，如何从文件读取? [英] Java - how to read from file when I used PrintWriter, BufferedWriter and FileWriter to write?

问题描述

我有将一些数据写入文件的方法.我使用如下所示的PrintWriter，BufferedWriter和FileWriter

I have method which writes some data to file. I use PrintWriter, BufferedWriter and FileWriter as shown below

public void writeToFile(String FileName){
    PrintWriter pw = null;
    try {
        pw = new PrintWriter(new BufferedWriter(new FileWriter(FileName)));
        for(Cars car : list){
            pw.println(car.getType());
            pw.println(car.getMaxSpeed());
            pw.println(car.getOwner());
            pw.println();
            pw.flush();
        }
        pw.close();
    }
    catch(IOException ex){
        System.err.println(ex);
    }
}

现在如何从文件读取此数据?我尝试使用InputStreamReader，BufferedReader和FileInputStream，但是我的NetBeans向我显示错误消息

Now how can I read this data from file? I tried to use InputStreamReader, BufferedReader and FileInputStream, but my NetBeans shows me an error message

    public void readFromFile() throws IOException {
        InputStreamReader fr = null;
        try {
            fr = new InputStreamReader(new BufferedReader(new FileInputStream(new FileReader("c:\\cars.txt"))));
            System.out.println(fr.read());
        } catch (Exception ex) {
            System.out.println(ex.getMessage());
        } finally {
            fr.close();
        }
    }  

此方法有什么问题?

推荐答案

BufferedReader in = new BufferedReader(new FileReader("file.in"));
BufferedWriter out = new BufferedWriter(new FileWriter("file.out"));

String line = in.readLine(); // <-- read whole line
StringTokenizer tk = new StringTokenizer(line);
int a = Integer.parseInt(tk.nextToken()); // <-- read single word on line and parse to int

out.write(""+a);
out.flush();

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