Java 将文件内容读入类对象
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Reading contents of a file into class objects
提问by Pastasaurus Rex
I have a text file of employee entries as follows:
我有一个员工条目的文本文件，如下所示：
000, first name1, middle name1
001, first name2, middle name2
002, first name3, middle name3
003, first name4, middle name4
004, first name5, middle name5
And I have a class Employee as follows:
我有一个 Employee 类，如下所示：
public class Employee {
public int id;
public String fName;
public String mName;
public String lName;
}
I've read the contents of the file into an array. But what I want is to construct an array of objects of class Employee, and a way for each attribute of the class to be initialised with each entry. Something like this:
我已将文件的内容读入数组。但我想要的是构造一个类 Employee 的对象数组，以及一种用每个条目初始化类的每个属性的方法。像这样的东西：
Employee e[] = new Employee[5];
Checking the details of each object in the array...
检查数组中每个对象的详细信息...
e[0].id = 000
e[0].fName = "first name1"
e[0].mName = "middle name1"
e[0].lName = "last name1"
Then,
然后，
e[1].id = 001
And so on...
等等...
Is there any way I can do this?
有什么办法可以做到这一点吗？
采纳答案by Ferdinand Neman
public class Employee {
public int id;
public String fName;
public String mName;
public String lName;
public Employee(String line) {
String[] split = line.split(",");
id = Integer.parseInt(split[0]);
fName = split[1];
mName = split[2];
lName = split[3];
}
}
Since you already read the file into array (of string I suppose).
由于您已经将文件读入数组（我想是字符串）。
String[] lines = ....;
Employee[] employees = new Employee[lines.length];
for(int i = 0; i < lines.length; i++) {
employees[i] = new Employee(lines[i]);
}
There you go... you have an array of employees.
你去吧……你有一群员工。
回答by user1438038
Read the file and loop over its content line by line. Then parse the lines and create a new Employee()in each iteration. Set your values, such as id and name. Finally, add your new Employeeinstance to a List<Employee>and continue with the next entry.
读取文件并逐行循环其内容。然后解析这些行并new Employee()在每次迭代中创建一个。设置您的值，例如 id 和 name。最后，将您的新Employee实例添加到 aList<Employee>并继续下一个条目。
// Read data from file
try (BufferedReader br = new BufferedReader(new FileReader(file))) {
// List to collect Employee objects
List<Employee> employees = new ArrayList<Employee>();
// Read file line by line
String line = "";
while ((line = br.readLine()) != null) {
// Parse line to extract individual fields
String[] data = this.parseLine(line);
// Create new Employee object
Employee employee = new Employee();
employee.id = Integer.valueOf(data[0]);
employee.fName = data[1];
employee.mName = data[2];
// Add object to list
employees.add(employee);
}
// Further process your Employee objects...
}
Also, there are CSV libraries that can handle all the nasty parts of reading a file that has comma separated values. I'd suggest using OpenCSV, for example.
此外，还有一些 CSV 库可以处理读取具有逗号分隔值的文件的所有令人讨厌的部分。例如，我建议使用OpenCSV。
回答by J.Lyu
Here already answers posted but I still gonna post mine...
这里已经发布了答案，但我仍然会发布我的......
package com.stackoverflow.java.test;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
public class Employee {
public int id;
public String fName;
public String mName;
public Employee(int id, String fName, String mName) {
this.id = id;
this.fName = fName;
this.mName = mName;
}
public static void main(String[] args) throws IOException {
Employee[] e = new Employee[5];
FileReader fr=new FileReader("YourDoc.txt");
BufferedReader br=new BufferedReader(fr);
String line="";
String[] arrs=null;
int num=0;
while ((line=br.readLine())!=null) {
arrs=line.split(",");
e[num] = new Employee(Integer.valueOf(arrs[0]), arrs[1], arrs[2]);
num++;
}
br.close();
fr.close();
for(int i=0 ; i< e.length; i++) {
System.out.println(e[i].id + " and " + e[i].fName + " and " + e[i].mName);
}
}
}
}
回答by Rustam
try :
尝试 ：
public static void main(String[] args) throws IOException {
File f1 = new File("d:\data.txt");
Scanner scanner = new Scanner(f1);
List<Employee1> empList=new ArrayList<>();
while(scanner.hasNextLine()){
String data[]=scanner.nextLine().split(",");
empList.add(new Employee(Integer.parseInt(data[0]),data[1],data[2],data[3]));
}
scanner.close();
System.out.println(empList);
}
Employee.java
雇员.java
class Employee{
public int id;
public String fName;
public String mName;
public String lName;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getfName() {
return fName;
}
public void setfName(String fName) {
this.fName = fName;
}
public String getmName() {
return mName;
}
public void setmName(String mName) {
this.mName = mName;
}
public String getlName() {
return lName;
}
public void setlName(String lName) {
this.lName = lName;
}
public Employee(int id, String fName, String mName, String lName) {
super();
this.id = id;
this.fName = fName;
this.mName = mName;
this.lName = lName;
}
@Override
public String toString() {
return "Employee [id=" + id + ", fName=" + fName + ", mName="
+ mName + ", lName=" + lName + "]";
}
}
