Question

公共类CreateNewUser {

public String fullName;
public int age;
public String school;
public String username;
public String password;

File file = new File("users.txt");


public void setFullName(String n) {
    this.fullName = n;
}
public void setAge(int a) {
    this.age = a;
}
public void setUsername(String u) {
    this.username = u;
}   
public void setPassword(String p) {
    this.password = p;
}


public String getFullName() {
    return fullName;
}
public String getSchool() {
    return school;
}
public int getAge() {
    return age;
}
public String getUsername() {
    return username;
}
public String getPassword() {
    return password;
}


//write all info on to .txt 
public void writeToInfoFile(String u, String p, String s, int a) {

}



//write username & password to a sepereate file (users.txt)
public void writeToUsersFile(String u, String p) {
    try{
    PrintWriter output = new PrintWriter(file);

    //if username exists throw exception
    output.println(username + " " + password);
    output.close();

    } catch (IOException ex){
        System.out.println("ERROR: file not found.");
    }
}

}

公共类CreateNewUserTest {

public static void main(String[] args) {
    Scanner in = new Scanner(System.in);

    CreateNewUser raul = new CreateNewUser();
    CreateNewUser jake = new CreateNewUser();


    String username, password;
    String uni;
    int age;

    //Raul
    System.out.printf("\tHello! Welcome to Ponder\t");
    System.out.println();
    System.out.print("Enter desired username: ");
    username = in.nextLine();
    raul.setUsername(username);

    System.out.println();
    System.out.print("Enter desired password: ");
    password = in.nextLine();
    raul.setPassword(password);

    raul.writeToUsersFile(username, password);


    in.close(); //close scanner


}

}

每当我添加新的用户名和密码时，它都会替换现有的用户名和密码。我希望它在新行上添加新的用户名和密码。

Answer 1

在函数writeToUsersFile中，替换以下行：

PrintWriter output = new PrintWriter(file);

带

PrintWriter output new PrintWriter(new FileWriter("users.txt", true));

还有一点，与你的问题无关：

除非这是一个玩具应用程序，否则我建议不要以明文形式将用户名和密码写入磁盘上的文件。您不希望密码位于磁盘上。您可能需要考虑在Java中使用一些密码存储（如OS X上的Keychain）或Java Key Store。

Answer 2

正在覆盖该文件，使用true替代文件。请改为： PrintWriter output = new PrintWriter(new FileWriter(file, true));

如何在新行上写入文件而不替换文件中的现有文本？

2 个答案: