让一个工厂类去生产出对象 （new ）来。

我们想要一个 形状，我们用工厂去生产出，圆形，方形。

package com.example.factory2;public interface Shape {void draw();
}

public class Square implements Shape {@Overridepublic void draw() {Log.d("LIU", "this is Square");}
}

public class Circle implements Shape {@Overridepublic void draw() {Log.d("LIU","this is circle");}
}

factory class:

public class ShapeFactory {public Shape getShape (int type) {if (type == 1) {return new Circle();} else if (type ==2) {return  new Square();} else {return null;}}
}

example and output:

        ShapeFactory shapeFactory = new ShapeFactory();Shape shape = shapeFactory.getShape(1);shape.draw();Shape shape2 = shapeFactory.getShape(2);shape2.draw();2024-10-02 22:23:47.705 14673-14673/com.example.factory2 D/LIU: this is circle
2024-10-02 22:23:47.706 14673-14673/com.example.factory2 D/LIU: this is Square

参考： 工厂模式 | 菜鸟教程