简单工厂模式

SimpleFactory.java

public class SimpleFactory {

    public static void main(String[] args) {
        Platform platform = Platform.get();
        System.out.println(platform);
    }


    public static class Platform {

        private static final Platform PLATFORM = findPlatform();

        public static Platform get() {
            return PLATFORM;
        }

        private static Platform findPlatform() {
            try {
                Class.forName("android.os.Build");
                return new Android();
            } catch (ClassNotFoundException e) {
            }
            try {
                Class.forName("java.util.Optional");
                return new Java();
            } catch (ClassNotFoundException ignored) {
            }
            return new Platform();
        }

    }

    public static class Android extends Platform {
        @Override
        public String toString() {
            return "Android";
        }
    }

    public static class Java extends Platform {
        @Override
        public String toString() {
            return "Java";
        }
    }

}