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Java Compiler command() method with example

Compiler Class command() method: Here, we are going to learn about the command() method of Compiler Class with its syntax and example.
Submitted by Preeti Jain, on December 02, 2019

Compiler Class command() method

• command() method is available in java.lang package.
• command() method is used to check the argument type and its fields and perform operations related to the command line.
• command() method is a static method, it is accessible with the class name and if we try to access the method with the class object then we will not get any error.
• command() method may throw an exception at the time of performing command-line operations.
  NullPointerException: This exception may throw when the given Object parameter is null exists.

Syntax:

    public static Object command(Object ob);

Parameter(s):

• Object ob – represents compiler defined parameter.

Return value:

The return type of this method is Object, it returns compiler–defined value and it includes null value.

Example:

// Java program to demonstrate the example 
// of Object command(Object ob) method of Compiler 

public class Parent {
    public static void main(String args[]) {
        // Creating a Parent and Child class object
        Parent p1 = new Parent();
        Parent p2 = new Child();

        // By using getClass() method is to get a Parent class
        Class cl1 = p1.getClass();
        System.out.println("p1.getClass() = " + cl1);

        // By using getClass() method is to get a Child class
        Class cl2 = p2.getClass();
        System.out.println("p2.getClass() = " + cl2);

        //By using command(Object ob) method to compile Child //class
        Object ob = Compiler.command("javac Child");
        System.out.println("ob = " + ob);
    }
}

class Child extends Parent {
    public void show() {
        System.out.println("We are in Child class: ");
    }
}

Output

p1.getClass() = class Parent
p2.getClass() = class Child
ob = null