When to implement ?
Suppose we have a situation ,
There are multiple action to execute based on a single value or criteria. There are several solution to do . We can use if.. else if ladder or switch case to do that and define the action in each separate method . But if the action feature grow then we need to refactor and transfer the defined action in class . It will we time consuming . So in that situation we can implement Command design pattern like below.
interface CampaignContactCommand {
void execute();
}
class PauseContactCommand implements CampaignContactCommand {
private ContactHelperNode node;
public PauseContactCommand(ContactHelperNode node) {
this.node = node;
}
@Override
public void execute() {
ContactPauseHelper helper = new ContactPauseHelper(node);
helper.pauseContact();
helper.release();
}
}
class ResumeContactCommand implements CampaignContactCommand{
private ContactHelperNode node;
public ResumeContactCommand(ContactHelperNode node) {
this.node = node;
}
@Override
public void execute() {
ContactResumeHelper helper = new ContactResumeHelper(node);
helper.resumeContact();
helper.release();
}
}
class UnsubscribeContactCommand implements CampaignContactCommand {
private ContactHelperNode node;
public UnsubscribeContactCommand(ContactHelperNode node) {
this.node = node;
}
@Override
public void execute() {
ContactUnSubHelper helper = new ContactUnSubHelper(node);
helper.unSubContact();
helper.release();
}
}
class CampaignContactCommandFactory {
private ContactHelperNode node;
public CampaignContactCommandFactory(ContactHelperNode node) {
this.node = node;
}
public CampaignContactCommand createCommand() {
switch (node.getRequest().getRequestType()) {
case PAUSE:
return new PauseContactCommand(node);
case RESUME:
return new ResumeContactCommand(node);
case UNSUB:
return new UnsubscribeContactCommand(node);
default:
return null;
}
}
}
