如何在java中刷新How

try {
    FileWriter fileWriter = new FileWriter("output.txt");
    BufferedWriter bufferedWriter = new BufferedWriter(fileWriter);
    
    bufferedWriter.write("Hello, World!");
    bufferedWriter.flush(); // 刷新缓冲区，将数据写入文件
    
    bufferedWriter.close();
} catch (IOException e) {
    e.printStackTrace();
}

try {
    FileWriter fileWriter = new FileWriter("output.txt");
    PrintWriter printWriter = new PrintWriter(fileWriter);
    
    printWriter.println("Hello, World!");
    printWriter.flush(); // 刷新缓冲区，将数据写入文件
    
    printWriter.close();
} catch (IOException e) {
    e.printStackTrace();
}

try {
    RandomAccessFile file = new RandomAccessFile("output.txt", "rw");
    FileChannel channel = file.getChannel();
    
    ByteBuffer buffer = ByteBuffer.wrap("Hello, World!".getBytes());
    channel.write(buffer);
    
    channel.force(true); // 刷新缓冲区，将数据写入文件
    
    channel.close();
    file.close();
} catch (IOException e) {
    e.printStackTrace();
}