并不是说您写入数据文本文件的方式有什么问题，只是我认为最好遵循更传统的CSV 样式文件格式，该格式专用于这种类型的数据存储。
例如，CSV 文件中的每一行都被视为一个记录行，并且通常使用逗号 (,) 来分隔该行中的字段数据列，而不是空格或制表符（就像在您的文件中一样），并且显然有充分的理由。最终需要检索文件中的数据，如果列字段中包含空格怎么办？例如，一些姓氏包含两个词（Simone de Beauvoir、Herbert M. Turner III、Ashley M. St. John 等）。必须对此进行一些考虑，是的，肯定有一种解决方法，但总而言之，使用除空格之外的更具体的分隔符更容易。您可能需要考虑将空格分隔符更改为逗号或分号分隔符。您甚至可以在您的 Person 类 toString() 方法中提供此选项：
/* Example Person Class... */
import java.io.Serializable;
public class Person implements Serializable {
// Default serialVersion id
private static final long serialVersionUID = 1212L;
private String name;
private String password;
private double money;
public Person() { }
public Person(String name, String password, double money) {
this.name = name;
this.password = password;
this.money = money;
}
public String toString(String delimiterToUse) {
return new StringBuffer("").append(this.name).append(delimiterToUse)
.append(this.password).append(delimiterToUse)
.append(String.format("%.2f", this.money)).toString();
}
@Override
public String toString() {
return new StringBuffer("").append(this.name).append(" ")
.append(this.password).append(" ")
.append(String.format("%.2f", this.money)).toString();
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public double getMoney() {
return money;
}
public void setMoney(double money) {
this.money = money;
}
}
在您的 save() 方法中，您可能有现有的行来利用空白的类默认分隔符 (" ")：
myWriter.println(people.get(i).toString());
或使用不同的分隔符，例如 逗号/空格组合 (", ")：
myWriter.println(people.get(i).toString(", "));
文件中的数据记录如下所示：
Donald Trump, myPassword, 23323.0
现在使用String#split() 之类的方法更容易解析上面的这条数据行，例如：
public static List<Person> readInPeople(String databaseFile) {
/* Declare a List Interface to hold all the read in records
of people from the database.txt file. */
List<Person> people = new ArrayList<>();
// 'Try With Resouces' is used to so as to auto-close the reader.
try (BufferedReader reader = new BufferedReader(new FileReader("database.txt"))) {
String dataLine;
while ((dataLine = reader.readLine()) != null) {
dataLine = dataLine.trim();
// Skip past blank lines.
if (dataLine.equals("")) {
continue;
}
/* Split the read in dataline delimited field values into a
String Array. A Regular Expression is used within the split()
method that takes care of any comma/space delimiter combination
situation such as: "," or ", " or " ," or " , " */
String[] dataLineParts = dataLine.split("\\s{0,},\\s{0,}");
// Ensure defaults for people.
String name = "", password = "";
double money = 0.0d;
/* Place each split data line part into the appropriate variable
IF it exists otherwise the initialized default (above) is used. */
if (dataLineParts.length >= 1) {
name = dataLineParts[0];
if (dataLineParts.length >= 2) {
password = dataLineParts[1];
if (dataLineParts.length >= 3) {
/* Make sure the data read in is indeed a string
representation of a signed or unsigned Integer
or double/float type numerical value. The Regular
Expression within the String#matches() method
does this. */
if (dataLineParts[2].matches("-?\\d+(\\.\\d+)?")) {
money = Double.parseDouble(dataLineParts[2]);
}
}
}
}
// Add the person from file into the people List.
people.add(new Person(name, password, money));
}
}
// Catch Exceptions...
catch (FileNotFoundException ex) {
System.err.println(ex.getMessage());
}
catch (IOException ex) {
System.err.println(ex.getMessage());
}
/* Return the list of people read in from the
database text file. */
return people;
}
要使用这种方法，你可以这样做：
// Call the readInPeople() method to fill the people List.
List<Person> people = readInPeople("database.txt");
/* Display the people List in Console Window
using a for/each loop. */
// Create a header for the data display.
// Also taking advantage of the String#format() and String#join() methods.
// String#join() is used to create the "=" Header underline.
String header = String.format("%-20s %-15s %s\n", "Name", "Password", "Money");
header += String.join("", Collections.nCopies(header.length(), "="));
System.out.println(header);
// Display the list. Also taking advantage of the printf() method.
for (Person peeps : people) {
System.out.printf("%-20s %-15s %s\n", peeps.getName(), peeps.getPassword(),
String.format("%.2f", peeps.getMoney()));
}
控制台显示可能如下所示：
Name Password Money
===========================================
Donald Trump myPassword 23323.00
Tracey Johnson baseball 2233.00
Simone de Beauvoir IloveFrance 32000.00