Class.forName() and Class.forName().newInstance() in Java

1. the Class.forName() in Java
2. the Class.forName().newInstance() in Java

This article will explain the difference between Class.forName() and Class.forName().newInstance() in Java.

the Class.forName() in Java

The Class-Type for the supplied name is returned by Class.forName(). It will return a reference to a class and load all static blocks, not instance methods, that are accessible.

The java.lang.Class class’s forName() function is used to retrieve the instance of such a class with the supplied class name. The class name is supplied as the string argument.

If the class cannot be found, a ClassNotFoundException is thrown.

Syntax:

public static Class<S> forName(String suppliedclass) throws ClassNotFoundException

Example:

The forName() technique is demonstrated in the applications below.

1. Create a Class type variable named exampleclass in the Main class and set the parameter of Class.ForName to ("java.lang.String").
2. Using the following line of code, you may see the name of the Class.

System.out.print(" The Example Class represents a class named : " + exampleclass.toString());

Source Code:

public class ForNameExample {
  public static void main(String[] args) throws ClassNotFoundException {
    Class exampleclass = Class.forName("java.lang.String");
    System.out.print("The Example Class represents a class named : " + exampleclass.toString());
  }
}

Output:

The Example Class represents a class named : class java.lang.String

the Class.forName().newInstance() in Java

Class’s instance is returned by newInstance(). Then that will return an object of that class, which we can use to invoke the instance methods.

The forName() method of the Class class, found in the java.lang package, returns the Class object for the argument, then loaded by the class loader. The class’s newInstance() function then returns a new instance.

Whenever you wish to load the class, execute its static blocks, and access its non-static parts, you’ll need an instance, which will require the following.

Syntax:

Class.forName("class").newInstance();

Example:

Create a class called MultiplyExample and initialize two integer type variables named z and x. This class returns an instance by multiplying two provided numbers.

class MultiplyExample {
  int Multiply(int z, int x) {
    return (z * x);
  }
}

Now create an object of MultiplyExample named m, after that apply Class.forName().newInstance().

MultiplyExample m = (MultiplyExample) Class.forName("MultiplyExample").newInstance();

At last, display the result by using the passed object to the Multiply function.

System.out.println("After Multiply result is " + m.Multiply(7, 5));

In this case, Class.forName("MultiplyExample") generates MultiplyExample.class, and newInstance() produces a Multiply class instance. In short, it’s the same as executing new MultiplyExample().

Source Code:

class MultiplyExample {
  int Multiply(int z, int x) {
    return (z * x);
  }
}
class Main {
  public static void main(String args[]) throws Exception {
    MultiplyExample m = (MultiplyExample) Class.forName("MultiplyExample").newInstance();
    System.out.println("After Multiply result is " + m.Multiply(7, 5));
  }
}

Output:

After Multiply result is 35