How to write code for Java factory design pattern
- 王林forward
- 2023-05-02 19:52:121257browse
Implementation
We will create a Shape interface and concrete classes that implement the Shape interface. A factory class ShapeFactory will be defined in the next step.
FactoryPatternDemo This is a demonstration class that will use ShapeFactory to obtain a Shape object. It will pass the information (CIRCLE/RECTANGLE/SQUARE) to the ShapeFactory to get the required object type.
The structure of implementing the factory pattern is shown in the figure below-
java-61.jpg
step 1
Create an interface-
Shape.java
publicinterfaceShape{
voiddraw();
}
Step 2
Create a concrete class that implements the same interface. Several categories are shown below-
Rectangle.java
publicclassRectangleimplementsShape{
@Override
publicvoiddraw(){
System.out.println("InsideRectangle::draw()method.");
}
}
Square.java
publicclassSquareimplementsShape{
@Override
publicvoiddraw(){
System.out.println("InsideSquare::draw()method.");
}
}
Circle.java
publicclassCircleimplementsShape{
@Override
publicvoiddraw(){
System.out.println("InsideCircle::draw()method.");
}
}
Step 3
Create a factory to generate objects of specific classes based on given information.
ShapeFactory.java
publicclassShapeFactory{
//usegetShapemethodtogetobjectoftypeshape
publicShapegetShape(StringshapeType){
if(shapeType==null){
returnnull;
}
if(shapeType.equalsIgnoreCase("CIRCLE")){
returnnewCircle();
}elseif(shapeType.equalsIgnoreCase("RECTANGLE")){
returnnewRectangle();
}elseif(shapeType.equalsIgnoreCase("SQUARE")){
returnnewSquare();
}
returnnull;
}
}
Step 4
Use a factory to obtain an object of a specific class by passing information such as type.
FactoryPatternDemo.java
publicclassFactoryPatternDemo{
publicstaticvoidmain(String[]args){
ShapeFactoryshapeFactory=newShapeFactory();
//getanobjectofCircleandcallitsdrawmethod.
Shapeshape1=shapeFactory.getShape("CIRCLE");
//calldrawmethodofCircle
shape1.draw();
//getanobjectofRectangleandcallitsdrawmethod.
Shapeshape2=shapeFactory.getShape("RECTANGLE");
//calldrawmethodofRectangle
shape2.draw();
//getanobjectofSquareandcallitsdrawmethod.
Shapeshape3=shapeFactory.getShape("SQUARE");
//calldrawmethodofcircle
shape3.draw();
}
}
Step 5
The verification output results are as follows-
InsideCircle::draw()method.
InsideRectangle::draw()method.
InsideSquare::draw()method.
The above is the detailed content of How to write code for Java factory design pattern. For more information, please follow other related articles on the PHP Chinese website!