appendFile到文本文件中，不会覆盖

Question

我对append方法不感兴趣了。

我有一个程序，可以输入信息，然后打印成文本文件。

问题是，我想在不覆盖的情况下将新输入的信息附加到文本文件中，这意味着如果我重新运行程序，我编码的信息将与程序最后一次运行时编码的信息一起出现在文本文件中。

请帮帮我。下面是程序：

@SuppressWarnings("resource")
public static void main(String[] args) throws IOException
{
   System.out.println("STUDENT INFORMATION");
   System.out.println("-------------------");
   System.out.println("Full Name            :   ");
    Scanner sc = new Scanner(System.in);
    String name = sc.nextLine();
   System.out.println("\nCourse and Year      :   ");
    String yearcourse = sc.nextLine();
   System.out.println("\nStudent Number       :   ");
    String studentnumber = sc.nextLine();
   System.out.println("\nE-mail Address       :   ");
    String eadd = sc.nextLine();
   System.out.println("\nCellphone Number     :   ");
    String cpnumber = sc.nextLine();
   System.out.println("\nGender               :   ");
    String gender = sc.nextLine();
   System.out.println("\nAge                  :   ");
    String age = sc.nextLine();
   System.out.println("\nDate of Birth        :   ");
    String dob = sc.nextLine();
   System.out.println("\nCivil Status         :   ");
    String status = sc.nextLine();
   System.out.println("\nAddress              :   ");
    String address = sc.nextLine();
   System.out.println("\n\n________________________________________________");
   System.out.println("STUDENT INFORMATION");
   System.out.println("\nName             :   " + name + "");
   System.out.println("Year and Course  :   " + yearcourse + "");
   System.out.println("Student Number   :   " + studentnumber + "");
   System.out.println("E-mail Address   :   " + eadd + "");
   System.out.println("Cellphone Number :   " + cpnumber + "");
   System.out.println("Gender           :   " + gender + "");
   System.out.println("Age              :   " + age + "");
   System.out.println("Date of Birth    :   " + dob + "");
   System.out.println("Civil Status     :   " + status + "");
   System.out.println("Address          :   " + address + "");
   System.out.println("");


    File file = new File("Student Information.txt");
    if(!file.exists())
    {
        file.createNewFile();
    }
    try (PrintWriter writer = new PrintWriter(file)){
        BufferedWriter bufferWritter = new BufferedWriter(writer);
        writer.println("\nSTUDENT INFORMATION:");
        writer.println("--------------------");
        writer.println("Name             :   " + name + "");
        writer.println("Year and Course  :   " + yearcourse + "");
        writer.println("Student Number   :   " + studentnumber + "");
        writer.println("E-mail Address   :   " + eadd + "");
        writer.println("Cellphone Number :   " + cpnumber + "");
        writer.println("Gender           :   " + gender + "");
        writer.println("Age              :   " + age + "");
        writer.println("Date of Birth    :   " + dob + "");
        writer.println("Civil Status     :   " + status + "");
        writer.println("Address          :   " + address + "");
        writer.flush();
    }
}

}

在这里面。如果我重新运行程序，文本文件将被新的编码信息覆盖。他们说要用append bufferwriter。但我真的迷路了。

Answer 1

尝试将您的代码更改为如下所示：

File file = new File("Student Information.txt");
    if(!file.exists())
    {
        file.createNewFile();
    }
    try(PrintWriter out = new PrintWriter(new BufferedWriter(new FileWriter(file, true)))) {
        out.println("\nSTUDENT INFORMATION:");
        out.println("--------------------");
        out.println("Name             :   " + name + "");
        out.println("Year and Course  :   " + yearcourse + "");
        out.println("Student Number   :   " + studentnumber + "");
        out.println("E-mail Address   :   " + eadd + "");
        out.println("Cellphone Number :   " + cpnumber + "");
        out.println("Gender           :   " + gender + "");
        out.println("Age              :   " + age + "");
        out.println("Date of Birth    :   " + dob + "");
        out.println("Civil Status     :   " + status + "");
        out.println("Address          :   " + address + "");
}catch (IOException e) {
    // Handle IO exception.
}

代码的这一部分：

new FileWriter(file,true)

告诉它在设置为true时进行追加，如on the docs所示。

或者你可以改变你的线路：

PrintWriter writer = new PrintWriter(file);

要这样做：

PrintWriter writer = new PrintWriter(new FileWriter(file,true));

Answer 2

而不是这个

PrintWriter writer = new PrintWriter(file);

尝尝这个

PrintWriter writer= new PrintWriter(new BufferedWriter(new FileWriter(file, true));

另请参阅

• How to append content to file in Java
• How to append text to an existing file in Java