Dependency Injection in Java without Spring IoC Framework........ How it is possible... A Simple way

You can first read Understanding Dependency Injection and its Importance, before this post for clearing Funda of Dependency Injection.
How can we this do programmatically.

• Create a interface Wheel.

    Interface Wheel(){
         rotate();
         applyBreak();
    }

• Create implementations

    class ChineseRubberWheel implements Wheel{
         //override and define
    }
    class NepaleseRubberWheel implements Wheel{
         //override and define
    }

• Create a txt file, where you write the valid name(say NepaleseRubberWheel ) of a Implementation of Wheel
• Read the txt file
• And finally, to Dynamically load the NepaleseRubberWheel as instance of Wheel;

    String wheeltoInject = ReadFromTXTFile();
    // Create Wheel object
    Wheel wheelToRun =(Wheel)     (Class.forName(wheelToInject).newInstance());
    // Execute methods of the wheel object.
    wheelToRun.rotate();
    wheelToRun.applyBreak();


This works for any implementation of Wheel. To change the Wheel on the Car just change name of Implementation on the txt file.