我正在尝试使用 PrintWriter.java， 但是却遇到了一个很奇怪的问题，我无法弄清楚我在这里缺少什么。

MyPrintWriter.java

public class MyPrintWriter {

    public static void main(String[] args) {

        File myFile = new File("myFileDirectory/myFileName.txt");
        try {

            FileWriter fw = new FileWriter(myFile);
            PrintWriter pw = new PrintWriter(fw);
            pw.println("Hello World!");

            pw.close();

        }   catch (FileNotFoundException e) {
                System.err.println("File not found: " + myFile);
        }   catch (Exception e) {
                e.printStackTrace();
        }       
    }

}

MyFileWriter.java

public class MyFileWriter {
    public static void main(String[] args) {

        File myFile = new File("myFileDirectory/myFileName.txt");
        try {
            InputStreamReader isr = new InputStreamReader(System.in);
            BufferedReader br = new BufferedReader(isr);

            FileWriter fw = new FileWriter(myFile);
            PrintWriter pw = new PrintWriter(fw);

            String input;
            input = br.readLine();
            while(input != null) {
                pw.println(input);
                input = br.readLine();
            }           
            br.close();
            pw.close();

        }   catch (FileNotFoundException e) {
                System.err.println("File not found: " + myFile);
        }   catch (Exception e) {
                e.printStackTrace();
        }       
    }

}

MyPrintWriter.java 很高兴写入 myFileName.txt 文件，但 MyFileWrite.java 不能。

有人可以帮助我了解我在这里想念的东西吗？