Question

首先，谢谢你所做的一切。我是Java的新手，我正在创建一个程序来询问用户名称，票据类型和罚金额。我正在获取该信息并将其写入文本文件（project.txt）。我正在使用Scanner readArray读取txt文件的内容，然后将内容排序到'list'数组中。我按字母顺序对列表进行了排序，现在我想在数组中搜索从用户输入中输入的关键字。该列表存储为“名称，票证类型，罚款（例如：迈克，超速，250.00”。当用户输入要搜索的名称（例如：迈克）时，我找不到...即使迈克，速度，100.00在project.txt中。我觉得它与逗号分隔值有关，但是，我必须以这种方式格式化。代码如下（请很好！我会在工作后清理代码... ）

import java.util.*;
import java.io.*;
import java.lang.reflect.Array;
import java.text.Collator;
public class Project {

    public static void main(String[] args) throws IOException {

    String name = "";
    String ticketType = "";
    double fine;
    char quit;
    boolean cont = true;

    while (cont){
    do {
        PrintStream out = new PrintStream(new FileOutputStream("Project.txt", true));
        Scanner input = new Scanner(System.in);

        System.out.println("Name:");
        name = input.nextLine();
        System.out.println("Ticket Type:");
        ticketType = input.nextLine();
        System.out.println("fine:");
        fine = input.nextDouble();
        System.out.println("press 'q' if you are done entering or 'c' to continue entering");
        quit = input.next().toLowerCase().charAt(0);
            out.print(name + ", ");
            out.print(ticketType + ", ");
            out.printf("%.2f",fine);
            out.println();
            out.close();
    }
    while (!(quit == 'q'));{
        System.out.println("done");
    }
    Scanner input = new Scanner(System.in);
    System.out.println("are you sure youre done");
    System.out.println("enter y to if your done, n to enter more");
    char Continue = input.next().toLowerCase().charAt(0);

    if (Continue == ('y')){
        cont = false;
        }
    //Done entering names to list
    //Now read in file to array and sort alphabetically

    }
    Scanner readArray = new Scanner(new File("Project.txt"));
    ArrayList<String> list = new ArrayList<String>();
    while (readArray.hasNext()){
        list.add(readArray.next().toLowerCase());

    }
    readArray.close();
    Collections.sort(list, Collator.getInstance()); //sort array alphabetically
    list.forEach(System.out::println); //print array as list ',' separated
    Scanner search = new Scanner(System.in);
    System.out.println("search keyword: ");
    String keyword = search.next().toLowerCase();
    System.out.println("searching for: " + keyword);
    if (list.contains(keyword)){
        System.out.println("found");
    }
    else {
        System.out.println(" not found");
    }
    }
}

Answer 1

您只读取文件中的下一个标记，读取整行，如下所示：

while (readArray.hasNext()){
    list.add(readArray.nextLine().toLowerCase());

}

同样可以说：

String keyword = search.nextLine().toLowerCase();

如果您只搜索名称，Arkadly是正确的：

while (readArray.hasNext()){
    String name = readArray.nextLine().toLowerCase().split(",")[0];

    list.add(name);

}

顺便说一下，ArrayList的.contains与String的.contains的工作方式不同。它在ArrayList中查找特定元素： https://www.tutorialspoint.com/java/java_arraylist_class.htm

Answer 2

正如Arkadiy正确提到的，该列表不包含“mike”，而是“mike，speeding，250.00”。

可能的天真搜索实现是：

  String keyword = search.next().toLowerCase();
  System.out.println("searching for: " + keyword);

  boolean found = false;
  for (String element : list) {
    if (element.contains(keyword)) {
      found = true;
    }
  }

  if (found) {
    System.out.println("found");
  }
  else {
    System.out.println(" not found");
  }
}

在Java ArrayList中搜索逗号分隔值 - 字符串和整数组合。

2 个答案: