Compare commits
3 Commits
all-contri
...
all-contri
Author | SHA1 | Date | |
---|---|---|---|
|
c95a2a1413 | ||
|
657c16720e | ||
|
d77915a3b7 |
@@ -1676,15 +1676,6 @@
|
||||
"contributions": [
|
||||
"translation"
|
||||
]
|
||||
},
|
||||
{
|
||||
"login": "ManviGoel26",
|
||||
"name": "Manvi Goel",
|
||||
"avatar_url": "https://avatars.githubusercontent.com/u/55682355?v=4",
|
||||
"profile": "https://github.com/ManviGoel26",
|
||||
"contributions": [
|
||||
"doc"
|
||||
]
|
||||
}
|
||||
],
|
||||
"contributorsPerLine": 7,
|
||||
|
@@ -10,7 +10,7 @@
|
||||
[](https://sonarcloud.io/dashboard?id=iluwatar_java-design-patterns)
|
||||
[](https://gitter.im/iluwatar/java-design-patterns?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
|
||||
<!-- ALL-CONTRIBUTORS-BADGE:START - Do not remove or modify this section -->
|
||||
[](#contributors-)
|
||||
[](#contributors-)
|
||||
<!-- ALL-CONTRIBUTORS-BADGE:END -->
|
||||
|
||||
<br/>
|
||||
@@ -312,7 +312,6 @@ This project is licensed under the terms of the MIT license.
|
||||
<tr>
|
||||
<td align="center"><a href="http://carlfx.wordpress.com"><img src="https://avatars.githubusercontent.com/u/1594624?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Carl Dea</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=carldea" title="Code">💻</a></td>
|
||||
<td align="center"><a href="https://github.com/Mozartuss"><img src="https://avatars.githubusercontent.com/u/32893711?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Mozartus</b></sub></a><br /><a href="#translation-Mozartuss" title="Translation">🌍</a></td>
|
||||
<td align="center"><a href="https://github.com/ManviGoel26"><img src="https://avatars.githubusercontent.com/u/55682355?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Manvi Goel</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=ManviGoel26" title="Documentation">📖</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
|
||||
|
138
twin/README.md
138
twin/README.md
@@ -13,144 +13,6 @@ tags:
|
||||
Twin pattern is a design pattern which provides a standard solution to simulate multiple
|
||||
inheritance in java
|
||||
|
||||
## Explanation
|
||||
|
||||
Real-world example
|
||||
|
||||
> Consider a game with a ball that needs features of two types, Game Item, and threads to function
|
||||
> smoothly in the game. We can use two objects, with one object compatible with the first type and
|
||||
> the other compatible with the second type.
|
||||
> The pair of objects together can function as one ball in the game.
|
||||
|
||||
In plain words
|
||||
|
||||
> It provides a way to form two closely coupled sub-classes that can act as a twin class having two ends.
|
||||
|
||||
Wikipedia says
|
||||
|
||||
> In software engineering, the Twin pattern is a software design pattern that allows developers
|
||||
> to model multiple inheritance in programming languages that do not support multiple inheritance.
|
||||
> This pattern avoids many of the problems with multiple inheritance.
|
||||
|
||||
**Programmatic Example**
|
||||
|
||||
Take our game ball example from above. Consider we have a game in which the ball needs to be both a `GameItem` and `Thread`.
|
||||
First of all, we have the `GameItem` class given below and the `Thread` class.
|
||||
|
||||
|
||||
```java
|
||||
|
||||
@Slf4j
|
||||
public abstract class GameItem {
|
||||
|
||||
public void draw() {
|
||||
LOGGER.info("draw");
|
||||
doDraw();
|
||||
}
|
||||
|
||||
public abstract void doDraw();
|
||||
|
||||
|
||||
public abstract void click();
|
||||
}
|
||||
|
||||
```
|
||||
|
||||
Then, we have subclasses `BallItem` and `BallThread` inheriting them, respectively.
|
||||
|
||||
```java
|
||||
|
||||
@Slf4j
|
||||
public class BallItem extends GameItem {
|
||||
|
||||
private boolean isSuspended;
|
||||
|
||||
@Setter
|
||||
private BallThread twin;
|
||||
|
||||
@Override
|
||||
public void doDraw() {
|
||||
|
||||
LOGGER.info("doDraw");
|
||||
}
|
||||
|
||||
public void move() {
|
||||
LOGGER.info("move");
|
||||
}
|
||||
|
||||
@Override
|
||||
public void click() {
|
||||
|
||||
isSuspended = !isSuspended;
|
||||
|
||||
if (isSuspended) {
|
||||
twin.suspendMe();
|
||||
} else {
|
||||
twin.resumeMe();
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
|
||||
@Slf4j
|
||||
public class BallThread extends Thread {
|
||||
|
||||
@Setter
|
||||
private BallItem twin;
|
||||
|
||||
private volatile boolean isSuspended;
|
||||
|
||||
private volatile boolean isRunning = true;
|
||||
|
||||
/**
|
||||
* Run the thread.
|
||||
*/
|
||||
public void run() {
|
||||
|
||||
while (isRunning) {
|
||||
if (!isSuspended) {
|
||||
twin.draw();
|
||||
twin.move();
|
||||
}
|
||||
try {
|
||||
Thread.sleep(250);
|
||||
} catch (InterruptedException e) {
|
||||
throw new RuntimeException(e);
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
public void suspendMe() {
|
||||
isSuspended = true;
|
||||
LOGGER.info("Begin to suspend BallThread");
|
||||
}
|
||||
|
||||
public void resumeMe() {
|
||||
isSuspended = false;
|
||||
LOGGER.info("Begin to resume BallThread");
|
||||
}
|
||||
|
||||
public void stopMe() {
|
||||
this.isRunning = false;
|
||||
this.isSuspended = true;
|
||||
}
|
||||
}
|
||||
|
||||
```
|
||||
|
||||
Now, when we need the ball, we can instantiate objects from both the `BallThread` and `BallItem` as a pair and pass them to its pair object so they can act together as appropriate.
|
||||
|
||||
```java
|
||||
|
||||
var ballItem = new BallItem();
|
||||
var ballThread = new BallThread();
|
||||
|
||||
ballItem.setTwin(ballThread);
|
||||
ballThread.setTwin(ballItem);
|
||||
|
||||
```
|
||||
|
||||
|
||||
## Class diagram
|
||||

|
||||
|
||||
|
Reference in New Issue
Block a user