Hello @kartik,
Implement your class with Serializable. Let's suppose that this is your entity class:
import java.io.Serializable;
@SuppressWarnings("serial") //With this annotation we are going to hide compiler warnings
public class Deneme implements Serializable {
    public Deneme(double id, String name) {
        this.id = id;
        this.name = name;
    }
    public double getId() {
        return id;
    }
    public void setId(double id) {
        this.id = id;
    }
    public String getName() {
        return this.name;
    }
    public void setName(String name) {
        this.name = name;
    }
    private double id;
    private String name;
}
We are sending the object called dene from X activity to Y activity. Somewhere in X activity;
Deneme dene = new Deneme(4,"Mustafa");
Intent i = new Intent(this, Y.class);
i.putExtra("sampleObject", dene);
startActivity(i);
In Y activity we are getting the object.
Intent i = getIntent();
Deneme dene = (Deneme)i.getSerializableExtra("sampleObject");
That's it.