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我查看了所有链接，但似乎无法得到我想要的东西。我有一个需要读入的文本文件。首先是文本文件格式：

3 STL NY Chi //all on one line
STL NY 575 //on its own line
NY Chi 550 //on its own line
STL Chi 225 //on its own line

我需要将 int 读入一个 int 变量，比如我们称之为计数。然后将同一条线上的实际城市放入一个数组中。接下来的几行需要读入一个数组，以将里程与该数组相关联，例如 [STL NY]=575。我只能使用数组。没有哈希表、列表、堆栈或队列。这是我到目前为止得到的，老实说它并不多。我真的可以使用一些帮助，因为我对这方面的“操作方法”感到非常困惑。

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

public class P3 {

/**
 * @param args the command line arguments
 */
public static int count;

public static void main(String[] args) {

    try {

        FileInputStream dataFile = new FileInputStream("Data.txt");
        //BufferedReader br = new BufferedReader(new InputStreamReader(dataFile));

        String line = br.readLine();

    }

    catch (IOException e) {
        System.err.println ("Unable to open file");
        System.exit(-1);
    }
  }
}

我想我到了那里，但我收到一个错误代码：“非静态变量城市无法从静态上下文中引用。” 我正在尝试通过打印来测试我的代码。谁能帮我打印这个？我想看看数组中有什么，以确保我做得正确。这是我的代码：

package p3;

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



class citiesDist {
    String cityOne;
    String cityTwo;
    int miles;
}

class city {
    String cityName;
    int numberLinks;
    citiesDist[] citiesDists;
}

public class P3 {

    city[] cities;

    void initCity(int len) {
        for (int i = 0; i < len; i++) {
            cities[i] = new city();
        }
    }

    void initCitiesDist (int index, int len) {
        for (int i = 0; i < len; i++) {
            cities[index].citiesDists[i] = new citiesDist();
        }
    }

    void parseFile() throws FileNotFoundException, IOException { 
        FileInputStream fstream = new FileInputStream("Data.txt"); 
        DataInputStream in = new DataInputStream(fstream); 
        BufferedReader br = new BufferedReader(new InputStreamReader(in)); 

        int numberCities = Integer.parseInt(br.readLine());
        cities = new city[numberCities];
        initCity(numberCities);

        for (int i = 0; i < numberCities; i++) {
            String line = br.readLine();
            int numberLink = Integer.parseInt(line.split(" ")[1]);
            cities[i].cityName = line.split(" ")[0];
            cities[i].numberLinks = numberLink;
            initCitiesDist (i, numberLink);

            for (int j = 0; j < numberLink; j++){
                line = br.readLine();
                cities[i].citiesDists[j].cityOne = line.split(" ")[0];
                cities[i].citiesDists[j].cityTwo = line.split(" ")[1];
                cities[i].citiesDists[j].miles = Integer.parseInt(line.split(" ")[2]);
            }
        }

    }

    public static void main(String args[]) {
        System.out.println("city" + cities.city);
    }
}
4

1 回答 1

1

如果您曾经对代码感到困惑，请不要考虑编程语言；它只会进一步混淆您的逻辑。（将算法与语言分开。）当你清楚地知道你想要完成什么时，添加你的语言（就“我如何完成这个特定的任务？”）。

最终目标

根据您的设计，您的目标是制作一个与每个城市之间的距离相关的图表。它看起来像这样：

     [STL][NY] [Chi]
[STL][0]  [575][25]
[NY] [575][0]  [550]
[Chi][25] [550][0]

Scanner就文件输入和类而言，这并不太难完成。

第一步

您必须提取图形的尺寸（即 3 x 3）。这是在输入文件的第一行中为您提供的。从 a 中获取一个Scanner带有 a的整数File并不难，只要确保您导入了正确的类，以及正确的错误处理（try...catch或者抛出异常）。

Scanner sc = new Scanner(new File("input.txt"));

You'll need two arrays - one for the cities, and one for the distances themselves. We don't know how large they are (you never assume the data in a file, you just assume the form of the data), so we have to get that from the file itself. Luckily, we are given an integer followed by the cities themselves. We will read this integer once and use it in multiple different locations.

String[] cities = new String[sc.nextInt()];
int[][] distances = new int[cities.length][cities.length];
for(int i = 0; i < cities.length; i++) {
    // Surely there's a method in Scanner that returns String that reads the _next_ token...
}

The Exercise to the Reader

You now have your data structure set up and ready to go. What you would need to do from here is bridge the gap between the cities array and distances array. Consider the order in which they arrived in the file, and the order in which we're encountering them. You would be well-served with some methodology or way to answer the question, 'Which came first - STL or NY?'

Give it a whirl and see if you can get further.

于 2012-04-07T01:45:27.343 回答