What will be the value of transient variable after de-serialization?

It’s default value.
e.g. if the transient variable in question is an int, it’s value after deserialization will be zero.

public class TestTransientVal implements Serializable{
   
    private static final long serialVersionUID = -22L;
    private String name;
    transient private int age;
    TestTransientVal(int age, String name) {
        this.age = age;
        this.name = name;
    }

    public static void main(String [] args) {
        TestTransientVal c = new TestTransientVal(1,"ONE");
        System.out.println("Before serialization: - " + c.name + " "+ c.age);
        try {
        FileOutputStream fs = new FileOutputStream("testTransients.ser");
        ObjectOutputStream os = new ObjectOutputStream(fs);
        os.writeObject(c);
        os.close();
        } catch (Exception e) { e.printStackTrace(); }


        try {
        FileInputStream fis = new FileInputStream("testTransients.ser");
        ObjectInputStream ois = new ObjectInputStream(fis);
        c = (TestTransientVal) ois.readObject();
        ois.close();
        } catch (Exception e) { e.printStackTrace(); }
        System.out.println("After de-serialization:- " + c.name + " "+ c.age);
        }
}

Result of executing above piece of code –
Before serialization: - Value of non-transient variable ONE Value of transient variable 1
After de-serialization:- Value of non-transient variable ONE Value of transient variable 0
Explanation –
The transient variable is not saved as the part of the state of the serailized variable, it’s value after de-serialization is it’s default value.