javaio流面试题

引的内容涉及到Java IO流的相关面试题。具体包括统计给定文件中给定字符串的出现次数的方法、将字符串写入文件的方法等。

1. 统计给定文件中给定字符串的出现次数的方法：

public static int countWordInFile(String filename, String word) {
    int counter = 0;
    try (FileReader fr = new FileReader(filename)) {
        try (BufferedReader br = new BufferedReader(fr)) {
            String line = null;
            while ((line = br.readLine()) != null) {
                int index = -1;
                while (line.length() >= word.length() && (index = line.indexOf(word)) >= 0) {
                    counter++;
                    line = line.substring(index + word.length());
                }
            }
        }
    } catch (Exception ex) {
        ex.printStackTrace();
    }
    return counter;
}

2. 将字符串写入文件的方法：

public static void writeFile(String str) {
    File file = new File("c:/test.txt");
    PrintStream ps = null;
    try {
        OutputStream fos = new FileOutputStream(file);
        ps = new PrintStream(fos);
        ps.print(str);
    } catch (FileNotFoundException e) {
        e.printStackTrace();
    } finally {
        ps.close();
    }
}