Bridge - Structural Design Pattern - Hello, world! I'm Anvay

🚡 Bridge

Bridge pattern is about preferring composition over inheritance. Implementation details are pushed from a hierarchy to another object with a separate hierarchy.

Decouple an abstraction from its implementation so that the two can vary independently.

Example: With and without the bridge pattern

interface WebPage {
    public void setTheme(Theme theme);
    public String getContent();
}
class AboutPage implements WebPage {
    protected Theme theme;
    public void setTheme(Theme theme) {
        this.theme = theme;
    }
    public String getContent() {
        return "About page in "+ this.theme.getColor();
    }
}
class CareersPage implements WebPage {
    protected Theme theme;
    public void setTheme(Theme theme) {
        this.theme = theme;
    }
    public String getContent() {
        return "Careers page in "+ this.theme.getColor();
    }
}
interface Theme {
    public Color getColor();
}
class DarkTheme implements Theme {
    public Color getColor() {
        return Color.DarkBlack;
    }
}
class LightTheme implements Theme {
    public Color getColor() {
        return Color.OffWhite;
    }
}
class AquaTheme implements Theme{
    public Color getColor() {
        return Color.LightBlue;
    }
}
Theme darkTheme = new DarkTheme();
AboutPage about = new AboutPage(darkTheme);
CareersPage careers = new CareersPage(darkTheme);

When to use? When we want to decouple an abstraction from its implementation so that the two can vary independently.