What is the transient keyword in Java?

The transient keyword in Java is used to avoid serialization. If any object of a data structure is defined as a transient, then it will not be serialized.

Serialization is the ​process of converting an object into a byte stream.

Code

In the code below, we have created a Member class object with a transient int id and a simple String name. Since the id is transient,​ it cannot be written in the file, so ​0 is stored instead.

import java.io.Serializable;

import java.io.*;

class TransientExample {

    public static class  Member implements Serializable{
        transient int id; // This will not serialized.
        String name;
        // constructor
        public Member(int i, String k) {
            this.id = id;
            this.name = k;
        }
    }

    public static void main(String args[]) throws Exception {
        Member temp =new Member( 2, "Clausia");//creating object
        //writing temp object into file
        FileOutputStream fread=new FileOutputStream("member.txt");
        ObjectOutputStream fout=new ObjectOutputStream(fread);
        fout.writeObject(temp);
        fout.flush();

        fout.close();
        fread.close();
        System.out.println("Data successfully saved in a file");

        // retrieving the data from file.
        ObjectInputStream fin=new ObjectInputStream(new FileInputStream("member.txt"));
        Member membr=(Member)fin.readObject();
        System.out.println(membr.id+" "+membr.name+" ");
        fin.close();
    }
}

Output

1.909s

Data successfully saved in a file 0 Clausia