Question

我编写了应保存对象ArrayList的程序，然后读取并添加新索引。从物理上讲，每个新条目都会添加到文件中，但我只能看到runnning后的第一个条目。我不知道。我认为我知道的是我再次编写相同的代码但是在一个类中。

保存：

class Zapis {
    private Operacje op = new Operacje();
    private GregorianCalendar gregorianCalendar = new GregorianCalendar();
    private Scanner scanner = new Scanner(System.in);
    private ArrayList<String> x = new ArrayList<String>();
    private Odczyt historia = new Odczyt();

public void test() throws IOException, ClassNotFoundException, NullPointerException {
    try {
        op.dzien = String.format("%tc", gregorianCalendar);
        op.kwota = scanner.nextInt();
        x.add(op.toString());
        ObjectOutputStream objectOutputStream = new ObjectOutputStream(new FileOutputStream("costam.bin",true));
        objectOutputStream.writeObject(x);
        objectOutputStream.close();
        ;
    } catch (NullPointerException e) {
        ObjectOutputStream objectOutputStream = new ObjectOutputStream(new FileOutputStream("costam.bin",true));
        op.dzien = String.format("%tc", gregorianCalendar);
        op.kwota = scanner.nextInt();
        x.add(op.toString());
        objectOutputStream.writeObject(x);
        objectOutputStream.close();
    }
}

读：

public class Odczyt {

public static ArrayList<String> array;

public void test() throws IOException, ClassNotFoundException {
    ObjectInputStream objectInputStream = new ObjectInputStream(new FileInputStream("costam.bin"));
    array = (ArrayList<String>) objectInputStream.readObject();
    int k = array.size();
    System.out.println(k);
    for (int i = 0; i < k; i++) {
        System.out.println(array.get(i));
    }
    objectInputStream.close();
}

Answer 1

public class Wszystko {
private static Operacje op = new Operacje();
private static Scanner scanner = new Scanner(System.in);
private static GregorianCalendar gregorianCalendar = new GregorianCalendar();
private static ArrayList<String> array;

public static void test() throws IOException, ClassNotFoundException {
    try {
        wczytaj();
        ustawOp();
        dodajDoArray();
        wydrukuj();
        zapisz();

    } catch (FileNotFoundException e) {
        ObjectOutputStream objectOutputStream = new ObjectOutputStream(new FileOutputStream("costam.bin"));
        op.dzien = String.format("%tc", gregorianCalendar);
        op.kwota = scanner.nextInt();
        array.add(op.toString());
        objectOutputStream.writeObject(array);
        objectOutputStream.close();
    }
}

public static void wczytaj() throws IOException, ClassNotFoundException {
    ObjectInputStream objectInputStream = new ObjectInputStream(new FileInputStream("costam.bin"));
    array = (ArrayList<String>) objectInputStream.readObject();
}
public static void ustawOp(){ op.dzien = String.format("%tc", gregorianCalendar);
    op.kwota = scanner.nextInt();}
public static void dodajDoArray(){
    array.add(op.toString());}
public static void wydrukuj(){
    int s = array.size();
    for(int i =0; i<s; i++){
        System.out.println(array.get(i));
    }
}
public static void zapisz() throws IOException {
    ObjectOutputStream objectOutputStream = new ObjectOutputStream(new FileOutputStream("costam.bin",true));
    objectOutputStream.writeObject(array);
    objectOutputStream.close();}

}

一切正常：D

在ileInputStream（name，boolean）之后读取

1 个答案: