java - Lesen mehrerer Objekte aus einer Datei, wie Sie waren, in ein array

Sind Sie gehen zu wollen, zu verwenden FileInputStream und ObjectInputStream.

FileInputStream fis = new FileInputStream("outputFile");
ArrayList<Object> objectsList = new ArrayList<Object>();
boolean cont = true;
try{
   ObjectInputStream input = new ObjectInputStream(fis);
   while(cont){
      Object obj = input.readObject();
      if(obj != null)
         objectsList.add(obj);
      else
         cont = false;
   }
}catch(Exception e){
   //System.out.println(e.printStackTrace());
}

InformationsquelleAutor MitchAman

Können wir Sie auf alle hinzufügen, das Objekt in eine Liste und dann serialisieren der Liste. Wieder können wir Deserialisieren der Liste und wir können die Liste Durchlaufen, um die Objekte , die wir suchen. Es wird die Verwendung der unten aufgeführten Klassen.
FileOutputStream
FileInputStream
ObjectInputStream
ObjectOutputStream

import java.io.Serializable;
import java.util.List;
import java.util.ArrayList;
import java.io.FileOutputStream;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.ObjectOutputStream;
import java.io.ObjectInputStream;

    public class MultiObjectSerialization {
        static String file = "helloFruits.txt";
        static ObjectOutputStream os;
        static ObjectInputStream is;

        public static void main(String[] args) throws IOException,
                ClassNotFoundException {
            Apples a = new Apples(1, "apple");
            Mango m = new Mango(2, "Mango");

            List<Object> fruits = new ArrayList<>();
            fruits.add(a);
            fruits.add(m);
            writeToFile(fruits);
            readFile();

        }

        public static void writeToFile(List<Object> fruits) throws IOException {
            os = new ObjectOutputStream(new FileOutputStream(file));
            os.writeObject(fruits);
            os.close();

        }

        public static void readFile() throws ClassNotFoundException, IOException {
            is = new ObjectInputStream(new FileInputStream(file));
            List<Object> input = (List<Object>) is.readObject();
            List<Object> checkList = new ArrayList<>();
            //this will contain the list of the objects
            for (Object l : input) {
                checkList.add(l.getClass().getSimpleName());
                if (l instanceof Apples) {
                    Apples app = (Apples) l;
                    System.out.println(app.id);
                    System.out.println(app.name);
                }
                if (l instanceof Mango) {
                    Mango app = (Mango) l;
                    System.out.println(app.id);
                    System.out.println(app.name);
                }
            }
            System.out.println(checkList);

            is.close();
        }
    }

    class Apples implements Serializable {
        private static final long serialVersionUID = 1L;
        int id;
        String name;

        public Apples(int id, String name) {
            this.id = id;
            this.name = name;
        }
    }

    class Mango implements Serializable {
        private static final long serialVersionUID = 1L;
        int id;
        String name;

        public Mango(int id, String name) {
            this.id = id;
            this.name = name;
        }
    }


  The Output is ::
    1
    apple
    2
    Mango
    [Apples, Mango]

InformationsquelleAutor pushkars

import java.io.*;
import java.util.*;
class ObjectReadWrite implements Serializable, Comparable <ObjectReadWrite>
{
    int no;
    String name;
    ObjectReadWrite(int i,String s)
    {
        this.no=i;
        this.name=s;
    }
    public String toString()
    {
        return "TP Data : "+this.no+":"+this.name;
    }
    public int compareTo(ObjectReadWrite a1)
    {
        return this.name.compareTo(a1.name);
    }
    public static void main(String args[]) throws Exception
    {
        TreeSet<ObjectReadWrite> aw = new TreeSet<ObjectReadWrite>();
        aw.add(new ObjectReadWrite(1,"ABC"));
        aw.add(new ObjectReadWrite(2,"DDF"));
        aw.add(new ObjectReadWrite(3,"DAF"));
        aw.add(new ObjectReadWrite(4,"DCF"));

        //Writing Objects From TreeSet
        ObjectOutputStream os=new ObjectOutputStream(
                    new FileOutputStream(
                    new File("Test.dat")));
        os.writeObject(aw);
        os.close();



        //Reading Objects into TreeSet
        TreeSet ar = new TreeSet();
        ObjectInputStream is=new ObjectInputStream(
                    new FileInputStream(
                    new File("Test.dat")));

        ar=(TreeSet)is.readObject();
        is.close();


        Iterator ir = ar.iterator();
        while(ir.hasNext())
        {
            System.out.println((ObjectReadWrite)ir.next());
        }

    }
}

InformationsquelleAutor CodingKick