如何拆分多行并将它们添加到arraylist

Question

我在从 txt 文件中分离信息时遇到问题，将该信息添加到列表并使用该信息创建对象

此应用程序的数据文件将以逗号分隔（每条数据将由 逗号），纯文本文件。要标记成绩类型（实验室、项目和测试成绩）的差异，请使用一个 将包含空数据字段。文件的第一行将包含可能的点 练习。学生 ID 将是字符串。

示例 ID,名字,姓氏,10,10,10,,100,100,,100

三个实验室（每个实验室值 10 分）

两个项目（每个项目价值 100 分）

一个测试（价值 100 分）

txt文件设置如下

ID,名字,姓氏,10,10,10,,100,100,,100

1234,乔,学生,10,8,9,,100,90,,100

5678,Another,Student,7,7,7,,75,75,,75

9012,Yet,Another,10,10,10,,65,70,,50

对象类

public class Student {
private String identifcation;
private String firstName;
private String lastName;
private List labs;
private List project;
private List test;

public Student(String identifcation, String firstName, String lastName, List<Integer> labs, List<Integer> projects, List<Integer> test) {
    this.identifcation = identifcation;
    this.firstName = firstName;
    this.lastName = lastName;
    this.labs = labs;
    this.project = projects;
    this.test = test;
    }
}

类中的readfile方法

public List<Student> decode() {

    List<Student> students = new ArrayList<Student>();

    while (this.scan.hasNext()) {
        List<Integer> labs = new ArrayList<Integer>();
        List<Integer> projects = new ArrayList<Integer>();
        List<Integer> tests = new ArrayList<Integer>();

        String identifcation = this.scan.next();
        String firstName = this.scan.next();
        String lastName = this.scan.next();

//help  int lab =      the labs
//help  labs.add(lab); should add the 3 labs
//help  int project = 
//help  projects.add(project); should add the 2 projects
//help  int test = 
//help  tests.add(test); should add the 1 test

        System.out.println(identifcation);
        System.out.println(firstName);
        System.out.println(lastName);

        System.out.print(this.scan.nextLine());         

        Student real = new Student(identifcation, firstName, lastName, labs, projects, tests);
        students.add(real);
    }
    return students;
} 

打印语句给了我一个输出

身份证，第一

姓名，姓氏

名称,10,10,10,,100,100,,100

1234,乔,学生,7,8,9,,80,90,,100

5678,Another,Student,7,7,7,,75,75,,75

9012,Yet,Another,10,10,10,,65,70,,50

他们应该给予

身份证

名字

姓氏

等等。

Answer 1

您可以使用带分隔符的字符串标记器作为“，”。您只需要逐行读取文件并将其标记化即可获取您的对象。我会写如下。

    import java.util.ArrayList;
    import java.util.List;
    import java.util.StringTokenizer;

    class Student {
        private String identifcation;

        @Override
        public String toString() {
            return "Student{" +
                    "identifcation='" + identifcation + '\'' +
                    ", firstName='" + firstName + '\'' +
                    ", lastName='" + lastName + '\'' +
                    ", labs=" + labs +
                    ", project=" + project +
                    ", test=" + test +
                    '}';
        }

        private String firstName;
        private String lastName;
        private List labs;
        private List project;
        private List test;

        public Student(String identifcation, String firstName, String lastName, List<Integer> labs, List<Integer> projects, List<Integer> test) {
            this.identifcation = identifcation;
            this.firstName = firstName;
            this.lastName = lastName;
            this.labs = labs;
            this.project = projects;
            this.test = test;
        }

    }

    public class Main {
        public static void main(String[] args) {
            String line = "example ID,First Name,Last Name,10,10,10,,100,100,,100";
            StringTokenizer tokenizer = new StringTokenizer(line,",");
            while(tokenizer.hasMoreElements()) {
                String id = tokenizer.nextToken();
                String fname = tokenizer.nextToken();
                String lName = tokenizer.nextToken();

                List<Integer> labs = new ArrayList<Integer>(){{
                    add(Integer.parseInt(tokenizer.nextToken()));
                    add(Integer.parseInt(tokenizer.nextToken()));
                    add(Integer.parseInt(tokenizer.nextToken()));
                }};

                List<Integer> project = new ArrayList<Integer>(){{
                    add(Integer.parseInt(tokenizer.nextToken()));
                    add(Integer.parseInt(tokenizer.nextToken()));
                }};

                List<Integer> test = new ArrayList<Integer>(){{
                    add(Integer.parseInt(tokenizer.nextToken()));
                }};
                Student s1 = new Student(id,fname,lName,labs,project,test);

                System.out.println(s1.toString());
            }
        }
    }

Answer 2

我建议逐行使用扫描仪 - 将整行存储为输入字符串。然后，您可以使用 Java string.split() 之类的函数拆分行，将“，”作为分隔符选项。这将允许您在数组中返回字符串，然后您可以根据需要将其排序到您的数组列表中。有关 split() 函数的更多详细信息，请参阅here

示例（可能要检查编译器）：

Scanner in = new Scanner(System.in);
String input;

//define arraylist outside of loop :-)
 ArrayList<String> arraylist1 = new ArrayList<>();
 ArrayList<String> arraylist2 = new ArrayList<>();


(while in.hasNext()){
    //store entire line
    input= in.nextLine();

     //Splits input string with , stores each string in an index position in data[]
     String[] data = input.split(",");

     arraylist1.add(data[0]);
     arraylist2.add(data[1]);
     //etc....
}

希望这会有所帮助！