Bridge pattern is used to decouple implementation and abstraction.
Check complete details and explanations about the Bridge pattern in the article: Bridge Design Pattern
This article demonstrates Bridge pattern implementations in Java. Check the following examples.
Example #1: UI Elements
In the example below we are implementing the Bridge pattern for a drawing UI Elements
Take a look at the class diagram.
package com.bigboxcode.designpattern.bridge.uielement;
public interface ColorSchema {
void setColor();
}
package com.bigboxcode.designpattern.bridge.uielement;
public class Red implements ColorSchema {
@Override
public void setColor() {
System.out.println("Setting proper color for Red color schema");
}
}
package com.bigboxcode.designpattern.bridge.uielement;
public class Green implements ColorSchema {
@Override
public void setColor() {
System.out.println("Setting proper color for Green color schema");
}
}package com.bigboxcode.designpattern.bridge.uielement;
public class Blue implements ColorSchema {
@Override
public void setColor() {
System.out.println("Setting proper color for Blue color schema");
}
}UI Element Abstract Class
package com.bigboxcode.designpattern.bridge.uielement;
public abstract class UIElement {
protected ColorSchema colorSchema;
public UIElement(ColorSchema colorSchema) {
this.colorSchema = colorSchema;
}
public abstract void printElement();
}package com.bigboxcode.designpattern.bridge.uielement;
public class Button extends UIElement{
public Button(ColorSchema colorSchema) {
super(colorSchema);
}
@Override
public void printElement() {
// Write code for printing element
System.out.println("Printing Button");
// Set color schema
colorSchema.setColor();
}
}package com.bigboxcode.designpattern.bridge.uielement;
public class Input extends UIElement{
public Input(ColorSchema colorSchema) {
super(colorSchema);
}
@Override
public void printElement() {
// Write code for printing element
System.out.println("Printing Input");
// Set color schema
colorSchema.setColor();
}
}package com.bigboxcode.designpattern.bridge.uielement;
public class Table extends UIElement{
public Table(ColorSchema colorSchema) {
super(colorSchema);
}
@Override
public void printElement() {
// Write code for printing table element
System.out.println("Printing Table");
// Set color schema
colorSchema.setColor();
}
}
Demo
package com.bigboxcode.designpattern.bridge.uielement;
public class Demo {
public static void main(String args[]) {
// Print a Red table
UIElement table = new Table(new Red());
table.printElement();
// Separator for clear view of demo result
System.out.println("\n------------------------------\n");
// Print a Green Input box
UIElement input = new Input(new Green());
input.printElement();
// Separator for clear view of demo result
System.out.println("\n------------------------------\n");
// Print a Blue Button
UIElement button = new Button(new Blue());
button.printElement();
// Separator for clear view of demo result
System.out.println("\n------------------------------\n");
// Print a Red Button
UIElement button2 = new Button(new Red());
button2.printElement();
}
}
Output
The output of the demo above will be like below.
Printing Table
Setting proper color for Red color schema
------------------------------
Printing Input
Setting proper color for Green color schema
------------------------------
Printing Button
Setting proper color for Blue color schema
------------------------------
Printing Button
Setting proper color for Red color schemaExample #2: Transport Seat
In this example, we are going to demonstrate different types of seat selection in multiple types of transport.
Let’s take a look at the class diagram first.
package com.bigboxcode.designpattern.bridge.transport;
public interface Seat {
void selectSeat();
}package com.bigboxcode.designpattern.bridge.transport;
public class BusinessClassSeat implements Seat {
@Override
public void selectSeat() {
System.out.println("Select an Business class seat");
}
}package com.bigboxcode.designpattern.bridge.transport;
public class EconomyClassSeat implements Seat{
@Override
public void selectSeat() {
System.out.println("Select an Economy class seat");
}
}package com.bigboxcode.designpattern.bridge.transport;
public abstract class Transport {
protected Seat seat;
public Transport(Seat seat) {
this.seat = seat;
}
public abstract void selectTransport();
}package com.bigboxcode.designpattern.bridge.transport;
public class Plane extends Transport {
public Plane(Seat seat) {
super(seat);
}
@Override
public void selectTransport() {
// Write code to select transport
System.out.println("Plane selected for transport");
// Select seat
seat.selectSeat();
}
}package com.bigboxcode.designpattern.bridge.transport;
public class Train extends Transport {
public Train(Seat seat) {
super(seat);
}
@Override
public void selectTransport() {
// Write code to select transport
System.out.println("Train selected for transport");
// Select seat
seat.selectSeat();
}
}Demo
package com.bigboxcode.designpattern.bridge.transport;
public class Demo {
public static void main(String args[]) {
Transport plane = new Plane(new BusinessClassSeat());
plane.selectTransport();
// Separator for clear view of demo result
System.out.println("\n------------------------------\n");
Transport plane2 = new Plane(new EconomyClassSeat());
plane2.selectTransport();
// Separator for clear view of demo result
System.out.println("\n------------------------------\n");
Transport train = new Train(new EconomyClassSeat());
train.selectTransport();
}
}
Output
Plane selected for transport
Select an Business class seat
------------------------------
Plane selected for transport
Select an Economy class seat
------------------------------
Train selected for transport
Select an Economy class seatSource Code
Use the following link to get the source code:
GitHub