Java supports both primitive types and non-primitive types. Primitive types are nothing but int, char, float, boolean, double etc. Non-primitive types are any classes like String, File or any other user defined types. Although primitive types can be created with out using new keyword, most of non-primitive types need new keyword.
Assume that we have the following classes defined. Student with out constructor and Book with constructor.
There are essentially three ways in which we can create an object with out using the new keyword.
Assume that we have the following classes defined. Student with out constructor and Book with constructor.
class Student
{
String name;
int marks;
char section;
}
class Book
{
Book(String name, String title)
{
this.name = name;
this.title = title;
}
String name;
String title;
}
There are essentially three ways in which we can create an object with out using the new keyword.
Using reflection
import java.lang.reflect.*;
class CreateObjectUsingReflection
{
public static void main(String[] args) throws ClassNotFoundException, InstantiationException, IllegalAccessException, IllegalArgumentException, SecurityException, InvocationTargetException, NoSuchMethodException
{
// Creating an object with default constructor
Class studentClass = Class.forName("Student");
Student rick = (Student) studentClass.newInstance();
rick.name = "Rick";
System.out.println(rick.name);
// Creating an object with two strings constructor
Class bookClass = Class.forName("Book");
Constructor twoStringsConstructor = bookClass.getDeclaredConstructor(String.class, String.class);
Book learn_java = (Book) twoStringsConstructor.newInstance("Learn Java Perfectly", "Merit Campus");
System.out.println(learn_java.title + " with " + learn_java.author);
}
}
