Question

所以我有一个名为“phone.txt”的文本文件，我将它加载到一个arraylist中，问题是现在我不知道如何在同一个类的方法中使用该arraylist。让我们说我的方法“optionP”，我希望客户能够在该arraylist中搜索一个名称，并显示该人的信息，我该怎么做？到目前为止我的代码是这样的：

import java.util.*;
import java.io.*;

public class Directory {

    Scanner kbd = new Scanner(System.in);
    ArrayList<Person> persons = new ArrayList<Person>();

    public void run() throws FileNotFoundException {
        String firstName;
        String lastName;
        String initial;
        String department;
        int telNum;

        File inFile = new File("phone.txt");
        Scanner in = new Scanner(inFile);

        while (in.hasNext()) {
            Person list;
            lastName = in.next();
            firstName = in.next();
            initial = in.next();
            department = in.next();
            telNum = in.nextInt();
            list = new Person(lastName, firstName, initial, department, telNum);
            persons.add(list);
        }
        in.close();
        int i;
        i = 0;
        while (i < persons.size()) {
            System.out.println(persons.get(i).toString());
            i++;
        }

        char userInput = kbd.next().charAt(0);
        if (userInput == 'p' || userInput == 'P') {
            optionP();
        } else if (userInput == 'l' || userInput == 'L') {
            optionL();
        } else if (userInput == 'r' || userInput == 'R') {
            optionR();
        } else if (userInput == 'c' || userInput == 'C') {
            optionC();
        } else if (userInput == 'a' || userInput == 'A') {
            optionA();
        } else {
            optionD();
        }

    }

    public void optionP() {

    }

    public void optionL() {

    }

    public void optionR() {

    }

    public void optionC() {

    }

    public void optionA() {

    }

    public void optionD() {

    }

    public class Person {
        String firstName;
        String lastName;
        String initial;
        String department;
        int telNum;

        public Person(String firstName, String lastName, String initial, String department, int telNum) {
            this.firstName = firstName;
            this.lastName = lastName;
            this.initial = initial;
            this.department = department;
            this.telNum = telNum;
        }
    } 
}

Answer 1

我猜这个文件有数据，你可以在控制台上打印时看到数据，如果没有，你必须先修复它

其次，如果你想从arrayList中读取

for(Person p:persons){ //do what you want }

Answer 2

OptionP需要浏览ArrayList并找到相应的结果

此外，因为您需要迭代ArrayList，所以最好使用LinkedList。

您可能还需要添加toString方法来描述结果。

import java.util.*;
import java.io.*;

public class Directory {

    Scanner kbd = new Scanner(System.in);
    List<Person> persons = new LinkedList<Person>();

    public void run() throws FileNotFoundException {
        String firstName;
        String lastName;
        String initial;
        String department;
        int telNum;

        File inFile = new File("/Users/zhaojing/Desktop/phone.txt");
        Scanner in = new Scanner(inFile);

        while (in.hasNext()) {
            Person list;
            lastName = in.next();
            firstName = in.next();
            initial = in.next();
            department = in.next();
            telNum = in.nextInt();
            list = new Person(lastName, firstName, initial, department, telNum);
            persons.add(list);
        }
        in.close();
        int i;
        i = 0;
        while (i < persons.size()) {
            i++;
        }

        char userInput = kbd.next().charAt(0);
        if (userInput == 'p' || userInput == 'P') {
            optionP();


        } else if (userInput == 'l' || userInput == 'L') {
            optionL();
        } else if (userInput == 'r' || userInput == 'R') {
            optionR();
        } else if (userInput == 'c' || userInput == 'C') {
            optionC();
        } else if (userInput == 'a' || userInput == 'A') {
            optionA();
        } else {
            optionD();
        }

    }

    public Person optionP() {
        String userInputFirstName = kbd.next();

        for (Person p : persons) {
            if (Objects.equals(userInputFirstName, p.firstName)) {
                System.out.println(p.toString());
                return p;
            }
        }

        return null;
    }

    public void optionL() {

    }

    public void optionR() {

    }

    public void optionC() {

    }

    public void optionA() {

    }

    public void optionD() {

    }

    public class Person {
        String firstName;
        String lastName;
        String initial;
        String department;
        int telNum;

        public Person(String firstName, String lastName, String initial, String department, int telNum) {
            this.firstName = firstName;
            this.lastName = lastName;
            this.initial = initial;
            this.department = department;
            this.telNum = telNum;
        }

        @Override
        public String toString() {
            return "result: Person{" +
                    "firstName='" + firstName + '\'' +
                    ", lastName='" + lastName + '\'' +
                    ", initial='" + initial + '\'' +
                    ", department='" + department + '\'' +
                    ", telNum=" + telNum +
                    '}';
        }
    }

}

如何将文本文件放入数组并与方法一起使用

2 个答案: