Java ObjectInputStream defaultReadObject() Method with Examples

by Online Tutorials Library July 22, 2022

Java ObjectInputStream defaultReadObject() Method

The defaultReadObject() method of ObjectInputStream class is used to read the non-static and non-transient fields of the current class from this stream, i.e, one cannot use defaultReadObject() to read the static fields. This may only be called from the readObject method of the class being desterilized. You cannot use defaultReadObject() directly.

Syntax

Parameter

No parameter is passed.

Returns

The return type is void.

Throws

NotActiveException , ClassNotFoundException , IOException.

Example 1

  import java.io.*;  public class ObjectInputStreamdefaultreadobjectExample1 {     public static void main(String[] args) {        try {             // create a new file with an ObjectOutputStream           FileOutputStream outstream = new FileOutputStream(“file1.txt”);           ObjectOutputStream objoutstream = new ObjectOutputStream(outstream);             // write something in the file           objoutstream.writeObject(new task());           objoutstream.flush();             // create an ObjectInputStream for the file we created before           ObjectInputStream objinputstram = new ObjectInputStream(new FileInputStream(“file1.txt”));             // read the object and print the string           task obj1 = (task) objinputstram.readObject();             // print the string that is in task class           System.out.println(“string that is in task class : ” + obj1.s);        } catch (Exception ex) {           ex.printStackTrace();        }     }     static class task implements Serializable {        String s = “tutorAspire”;           // using defaultReadObject() with read() method        private void readObject(ObjectInputStream in)           throws IOException, ClassNotFoundException {            // read the non static fields           in.defaultReadObject();        }     }  }  

Output:

string that is in task class : TutorAspire

Example 2

  // file 1 and file 2 must be present in the same directory.   import java.io.*;  public class ObjectInputStreamdefaultreadobjectExample2 {     public static void main(String[] args) {        try {            // create a new file with an ObjectOutputStream            FileOutputStream outstream = new FileOutputStream(“file1.txt”);            ObjectOutputStream objoutstream = new ObjectOutputStream(outstream);            FileInputStream instream = new FileInputStream(“file2.txt”);             ObjectInputStream objinstream = new ObjectInputStream(instream);            String str=objinstream.toString();            // write something in the file            objoutstream.writeObject(new task());            objoutstream.writeObject(str);            objoutstream.flush();             // create an ObjectInputStream for the file we created before           ObjectInputStream objinputstram = new ObjectInputStream(new FileInputStream(“file1.txt”));           // read and print an object and cast it as string           System.out.println(“” + (String) objinstream.readObject());             // read the object and print the string           task obj1 = (task) objinputstram.readObject();             // print the string that is in task class           System.out.println(“string that is in task class  : ” + obj1.s);        } catch (Exception ex) {           ex.printStackTrace();        }     }     static class task implements Serializable {        String s = “tutorAspire”;            // using defaultReadObject() with read() method        private void readObject(ObjectInputStream in)           throws IOException, ClassNotFoundException {            // read the non static fields           in.defaultReadObject();        }     }  }  

Output:

[email protected]  string that is in task class  : TutorAspire

Next TopicJava ObjectInputStream

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