Factory mode

Create an interface ：Shape.java

public interface Shape {
   void draw();
}

Create entity classes that implement interfaces ：Rectangle.java,Square.java,Circle.java

public class Rectangle implements Shape {

   @Override
   public void draw() {
      System.out.println("Inside Rectangle::draw() method.");
   }
}

public class Square implements Shape {

   @Override
   public void draw() {
      System.out.println("Inside Square::draw() method.");
   }
}

public class Circle implements Shape {

   @Override
   public void draw() {
      System.out.println("Inside Circle::draw() method.");
   }
}

Create a factory , Generate object of entity class based on given information ：ShapeFactory.java

public class ShapeFactory {
    
   // Use  getShape  Method to get the shape type object 
   public Shape getShape(String shapeType){
      if(shapeType == null){
         return null;
      }        
      if(shapeType.equalsIgnoreCase("CIRCLE")){
         return new Circle();
      } else if(shapeType.equalsIgnoreCase("RECTANGLE")){
         return new Rectangle();
      } else if(shapeType.equalsIgnoreCase("SQUARE")){
         return new Square();
      }
      return null;
   }
}

Using the plant , Get the object of entity class by passing type information ：FactoryPatternDemo.java

public class FactoryPatternDemo {

   public static void main(String[] args) {
      ShapeFactory shapeFactory = new ShapeFactory();

      // obtain  Circle  The object of , And call its  draw  Method 
      Shape shape1 = shapeFactory.getShape("CIRCLE");
      // call  Circle  Of  draw  Method 
      shape1.draw();

      // obtain  Rectangle  The object of , And call its  draw  Method 
      Shape shape2 = shapeFactory.getShape("RECTANGLE");
      // call  Rectangle  Of  draw  Method 
      shape2.draw();

      // obtain  Square  The object of , And call its  draw  Method 
      Shape shape3 = shapeFactory.getShape("SQUARE");
      // call  Square  Of  draw  Method 
      shape3.draw();
   }
}

 Output ：
Inside Circle::draw() method.
Inside Rectangle::draw() method.
Inside Square::draw() method.