5 Ways to Create Java Objects: From new Keyword to Deserialization

As Java developers we often need to create objects, and beyond the usual new operator or Spring containers there are several alternative techniques.

1. Using the new keyword

The most common way, invoking any constructor (no‑arg or parameterized).

Employee emp1 = new Employee();

2. Using Class newInstance()

Invoke the no‑arg constructor via reflection.

Employee emp2 = (Employee) Class.forName("org.programming.mitra.exercises.Employee").newInstance();

Or the shortcut:

Employee emp2 = Employee.class.newInstance();

3. Using Constructor newInstance()

Obtain a Constructor object and call its newInstance() method, which can also invoke parameterized or private constructors.

Constructor<Employee> constructor = Employee.class.getConstructor();
Employee emp3 = constructor.newInstance();

4. Using clone()

When clone() is called, the JVM creates a new object without invoking any constructor. The class must implement Cloneable and define clone().

Employee emp4 = (Employee) emp3.clone();

5. Using deserialization

Reading a serialized object also creates a new instance without calling a constructor; the class must implement Serializable.

ObjectInputStream in = new ObjectInputStream(new FileInputStream("data.obj"));
Employee emp5 = (Employee) in.readObject();

Example Employee class

class Employee implements Cloneable, Serializable {
    private static final long serialVersionUID = 1L;
    private String name;
    public Employee() { System.out.println("Employee Constructor Called..."); }
    public String getName() { return name; }
    public void setName(String name) { this.name = name; }
    @Override public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        Employee employee = (Employee) o;
        return Objects.equals(name, employee.name);
    }
    @Override public int hashCode() { return Objects.hash(name); }
    @Override public String toString() { return String.format("Employee{name='%s'}", name); }
    @Override public Object clone() {
        try { return super.clone(); } catch (CloneNotSupportedException e) { e.printStackTrace(); return null; }
    }
}

Complete program demonstrating all five methods

public class ObjectCreation {
    public static void main(String[] args) throws Exception {
        // 1. new keyword
        Employee emp1 = new Employee();
        emp1.setName("emp1");
        // 2. Class.newInstance()
        Employee emp2 = Employee.class.newInstance();
        emp2.setName("emp2");
        // 3. Constructor.newInstance()
        Constructor<Employee> constructor = Employee.class.getConstructor();
        Employee emp3 = constructor.newInstance();
        emp3.setName("emp3");
        // 4. clone()
        Employee emp4 = (Employee) emp3.clone();
        emp4.setName("emp4");
        // serialize emp4
        try (ObjectOutputStream out = new ObjectOutputStream(new FileOutputStream("data.obj"))) {
            out.writeObject(emp4);
        }
        // 5. deserialization
        Employee emp5;
        try (ObjectInputStream in = new ObjectInputStream(new FileInputStream("data.obj"))) {
            emp5 = (Employee) in.readObject();
            emp5.setName("emp5");
        }
        System.out.println(emp1 + ", hashcode : " + emp1.hashCode());
        System.out.println(emp2 + ", hashcode : " + emp2.hashCode());
        System.out.println(emp3 + ", hashcode : " + emp3.hashCode());
        System.out.println(emp4 + ", hashcode : " + emp4.hashCode());
        System.out.println(emp5 + ", hashcode : " + emp5.hashCode());
    }
}

Sample output

Employee Constructor Called...
Employee Constructor Called...
Employee Constructor Called...
Employee{name='emp1'}, hashcode : 3117192
Employee{name='emp2'}, hashcode : 3117193
Employee{name='emp3'}, hashcode : 3117194
Employee{name='emp4'}, hashcode : 3117195
Employee{name='emp5'}, hashcode : 3117196

The program shows that methods 1‑3 invoke constructors (visible in the printed messages), while methods 4 and 5 create objects without calling a constructor.