为什么我不能创建一个类？ 我正在尝试使用 Animal 数组来容纳不同的动物

Question

我正在尝试创建一个动物数组来尝试保存不同类型的动物/所有者的信息。 一直试图解决这个问题阅读了 2 个小时，但没有任何效果。 任何人都可以指出我正确的方向吗？ 另外我将如何将信息从 URL 导入数组？

import java.net.URL;
import java.math.BigInteger; 
import java.net.URL; 
import java.net.HttpURLConnection;
import static java.util.Arrays.sort;
public  class janesj_Program5 {
    public static void main(String[] args) {
        Animal[] j = new Animal[1];
        storeFile(j);
        sort(j);
        printArray(j);
    }
    public  static  class Animal {
        String OwnerName;
        int birthYear;
        public int billBalance;
        String Species;
        String feature;
        public  Animal() {}
        public Animal(String OwnerName,int birthYear,int billBalance,String Species,String feature) {
            this.OwnerName = OwnerName;
            this.birthYear = birthYear;
            this.billBalance = billBalance;
            this.Species = Species;
            this.feature = feature;
        }


        public int getBalance() {
            return billBalance;
        }
        public String toString() {
            return OwnerName + "\t" + birthYear + "\t" + getBalance() + "\t" + Species + "\t" + feature;
        }

        }
    public static void storeFile(Animal[] x) {
    String URLString = "http://yoda.kean.edu/~pawang/CPS2231/Program5_veterinarian_input.txt";
    try {
        java.net.URL url = new java.net.URL(URLString);
        int count = 0;
        Scanner input = new Scanner(url.openStream());
        while(input.hasNext()) {
            String line = input.nextLine();
            count+= line.length();
            x = new Animal[count];
        }
    }catch(java.net.MalformedURLException ex){
        System.out.println("Invalid URL");
    }
    catch(java.io.IOException ex) {
        System.out.println("I/O Errors: no such file");
    }

        }
    public static class sorts extends Animal implements Comparator<Animal> {
        public int compare(Animal a, Animal b) {
            return a.getBalance() - b.getBalance();
        }

    }
    public static void printArray(Animal[] x) {
        System.out.println("\t Veterinarian Services Report \t Page:1");
        System.out.println("    ==================================");
        System.out.println("No\tOwner Name\tYear\tBalance\tSpecies\tLegs\tFeature");
        System.out.println("== ====================  ==== ============ ============ ============");
        for(int i = 1; i<=x.length;i++) {
            System.out.println(i + "  " + x.toString());
        }
    }
        }

Answer 1

正如MTilsted所指出的那样，你真的应该在它自己的.java文件中拥有你的 Animal 类。

如果您计划创建一个 Animal 对象数组，其中填充这些对象的数据来自数据文件，那么您需要意识到数组的大小是固定的，它们不能随心所欲地增长（至少不是没有更多编码）。 您需要知道数据文件中如何包含动物，以便正确调整 Animal 数组的大小。 您很幸运，从外观上看，您的数据文件包含文件第一行中的动物数量（在读取实际动物数据时需要忽略）。

首先，确保文件确实存在。 如果它甚至不存在或者与其位置的连接有问题，那么心痛是没有意义的。 完成后，您可以声明您的 Animals 数组并将其初始化为适当的大小，以便处理您将要重新读入该数组的所有数据行。

下面是您的代码，用于演示如何实现这一点。

import java.io.IOException;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.Scanner;


public class AnimalCare {

    static Animals[] animals;  // Declare The Anmimal Array as a class member variable

    public static void main(String[] args) {
        try {
            URL url = new URL("http://yoda.kean.edu/~pawang/CPS2231/Program5_veterinarian_input.txt");
            int lines = 0;
            // Get the number of lines in file 
            try (Scanner s = new Scanner(url.openStream())) {
                String firstFileLine = "";
                while (firstFileLine.equals("")) {
                    firstFileLine = s.nextLine().trim();
                    if (!firstFileLine.equals("")) {
                        lines = Integer.parseInt(firstFileLine);
                    }
                }
            }
            catch (IOException ex) {
                String msg = "";
                if (!ex.getMessage().equals(url.toString())) {
                    msg = "No Network Connection!";
                }
                else {
                    msg = "File Not Found! - " + ex.getMessage();
                }
                System.err.println(msg);
            }

            // Declare our Animals Array.
            animals = new Animals[lines];

            // Re-read the data file on network...
            try (Scanner s = new Scanner(url.openStream())) {
                int i = 0;
                String dataLine;
                s.nextLine(); // Skip the first line of file!
                while (s.hasNextLine()) {
                    dataLine = s.nextLine().trim();
                    // Skip blank lines (if any)
                    if (dataLine.equals("")) {
                        continue;
                    }
                    String[] dataParts = dataLine.split("\\s+");
                    animals[i] = new Animals(dataParts[0], 
                                    Integer.parseInt(dataParts[1]), 
                                    Integer.parseInt(dataParts[2]), 
                                    dataParts[3], 
                                    dataParts[4]);
                    i++; // Increment i to create the next index value for array
                }
                // The Animals array is now filled with network file data
            }
            catch (IOException ex) {
                String msg = "";
                if (!ex.getMessage().equals(url.toString())) {
                    msg = "No Network Connection!";
                }
                else {
                    msg = "File Not Found! - " + ex.getMessage();
                }
                System.err.println(msg);
            }
        }
        catch (MalformedURLException ex) {
            System.err.println(ex.getMessage());
        }

        // Display the Animals array within the Console Window...
        for (int i = 0; i < animals.length; i++) {
            System.out.println(animals[i].toString());
        }
    }

}

和动物类：

import java.util.Arrays;


public class Animals {

    private String OwnerName;
    private int birthYear;
    private int billBalance;
    private String Species;
    private String feature;

    //-----------------  Constructors -------------------
    public Animals() { }

    public Animals(String OwnerName, int birthYear, int billBalance, String Species, String feature) {
        this.OwnerName = OwnerName;
        this.birthYear = birthYear;
        this.billBalance = billBalance;
        this.Species = Species;
        this.feature = feature;
    }

    public Animals(Object[] data) {
        if (data.length != 5 || !(data[0] instanceof String) || 
                !(data[1] instanceof Integer) || !(data[2] instanceof Integer) || 
                !(data[3] instanceof String) || !(data[4] instanceof String)) {
            throw new IllegalArgumentException("Error in Animals Constructor data array! "
                    + "Insufficiant data or invalid data element!" + System.lineSeparator() + 
                    Arrays.deepToString(data));
        }
        this.OwnerName = data[0].toString();
        this.birthYear = (int) data[1];
        this.billBalance = (int) data[2];
        this.Species = data[3].toString();
        this.feature = data[4].toString();
    }
    //---------------------------------------------------

    public int getBalance() {
        return billBalance;
    }

    public String getOwnerName() {
        return OwnerName;
    }

    public void setOwnerName(String OwnerName) {
        this.OwnerName = OwnerName;
    }

    public int getBirthYear() {
        return birthYear;
    }

    public void setBirthYear(int birthYear) {
        this.birthYear = birthYear;
    }

    public int getBillBalance() {
        return billBalance;
    }

    public void setBillBalance(int billBalance) {
        this.billBalance = billBalance;
    }

    public String getSpecies() {
        return Species;
    }

    public void setSpecies(String Species) {
        this.Species = Species;
    }

    public String getFeature() {
        return feature;
    }

    public void setFeature(String feature) {
        this.feature = feature;
    }

    @Override
    public String toString() {
        String string = String.format("%-10s %-8d %-8d %-10s %-15s", 
                OwnerName, birthYear, getBalance(), Species, feature);
        return string;
    }

}