ObjectOutputStream重复输出

Question

在这种情况下，甚至找不到问题本身。当程序从objects.dat读取时，输出只是数组中最后一个对象的变量。Program output screenshot.我已经梳理了代码好几次，都找不到问题。据我所知，一切都很顺利，直到它尝试序列化并将对象写/读到"objects.dat“。如果有人能给我一个提示，告诉我问题是什么，或者如何修复它，我将不胜感激。我认为问题可能出在readFile或writeFile方法中，但我不能确定。

目标是创建一个对象数组，序列化它，将其写入文件，然后读取该文件。

public class Test implements Serializable{

public static void main(String[] args) throws InvalidTestScore, ClassNotFoundException, IOException {
    Scanner keyboard = new Scanner(System.in);
    int userInput;
    final int ARRAYLENGTH;
    //get info for ARRAYLENGTH and make a TestScore array.
    System.out.println("How many test scores are you finding the average of? (ex. 6 tests): ");
    ARRAYLENGTH = keyboard.nextInt();
    TestScores[] scoreArray = new TestScores[ARRAYLENGTH];
    //populate scoreArray with TestScore objects.
    for (int counter = 0; counter < scoreArray.length; counter++)
    {
       System.out.println("Enter the score of test " + (counter + 1) + ": ");
       userInput = keyboard.nextInt();
       scoreArray[counter] = new TestScores(counter, userInput);

    }

    System.out.println("Now writing the object to 'objects.dat'...");
    TestScores.writeFile(scoreArray);

    System.out.println("Now reading the object from 'objects.dat'...");
    TestScores.readFile(ARRAYLENGTH);
}



 package scoresPackage;
import java.io.*;

public class TestScores implements Serializable {

    static TestScores[] scoreArray, scoreRead;
    static int score, name;

    TestScores (int test, int num) throws InvalidTestScore
    {
        name = test;
        score = num;

        if (num >= 100 || num <= 0)
           {
              throw new InvalidTestScore();
           }
    }
    public static void writeFile(TestScores[] test) throws IOException
    {
        FileOutputStream outStream = new FileOutputStream("objects.dat");
        try (ObjectOutputStream objectOut = new ObjectOutputStream(outStream)) {
            for (int counter = 0; counter < test.length; counter++)
            {
                objectOut.writeObject(test[counter]);
                objectOut.reset();
            }
        }
        System.out.println("Writing success.");
    }
    public static void readFile(int ALENGTH) throws IOException, ClassNotFoundException
    {
        FileInputStream inStream = new FileInputStream("objects.dat");
        try (ObjectInputStream objectIn = new ObjectInputStream(inStream)) {
            scoreRead = new TestScores[ALENGTH];

            for (int counter = 0; counter < ALENGTH; counter++)
            {
                scoreRead[counter] = (TestScores) objectIn.readObject();
                System.out.println("Test " + name + " Score: " + score);

            }
        }
        System.out.println("Reading success.");

    }

Answer 1

这就是问题：

static int score, name;

它与ObjectOutputStream无关-这意味着您不是每个TestScores实例都有一个分数和一个名称，而是一个score变量和一个name。您的TestScores构造函数将覆盖这些变量，因此当您创建第二个实例时，您已经丢失了向用户请求的第一个name/score数据。要了解这一点，一个很好的方法是完全删除ObjectOutputStream和ObjectInputStream代码:一旦您要求用户提供所有信息，如果您试图将所有信息打印到控制台，会发生什么情况？(基本上，您将看到相同的行为:您将只看到最后输入的值。)

您需要实例字段，而不是静态字段：

int score, name;

(或者更好的做法是，将它们设置为私有...这不是我对代码所做的唯一更改，但它是一个起点。)

有关静态字段和实例字段之间差异的更多详细信息，请参阅Java tutorial。