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

I am trying to create a animal array to try and hold the information of different types of animals/owners. Been trying to solve this for 2 hours reading the book but nothing is working. Can anyone point me to the right direction? Also how would I go about importing information from a URL to a array?

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

As so kindly pointed out by MTilsted you really should have your Animal class within its own .java file.

If you plan to create an array of Animal objects where the data to fill those objects is coming from a data file then you need to realize that arrays are of a fixed size, they can't just grow on a whim (at least not without more coding). You would need to know how may animals are contained within the data file so as to properly size your Animal array. Your in luck, by the look of it your data file contains the number of animals within the first line of the file (which needs to be ignored when reading in the actual animal data).

First, make sure the file actually exist. No sense going through heartache if it's not even there or there is something wrong with the connection to its' location. Once done, you can declare and initialize your Animals array to the proper size so as to handle all the data rows you are about to re-read into the array.

Below is your code to demonstrate how this can be accomplished.

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());
        }
    }

}

And the Animals Class:

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;
    }

}