Version Contorl Javacaup

package ir.javacup.vc;

import java.util.*;
import java.util.Map.Entry;

public class VersionControl {

	private final Project project;
	private List <Project> history=new ArrayList<Project>();
	
	public VersionControl(Project project) {
		this.project = project;
	}

	public Project takeSnapshot() {
		Project photo=new Project(project.getName(),project.getVersion());
		
		for(Entry<String, StringBuilder> e:project.getSourceCodes().entrySet())
		{
			photo.getSourceCodes().put(e.getKey(), new StringBuilder(e.getValue()));

		}
		history.add(photo);
		return photo;
	}

	public void goBack() {
		if(history.isEmpty()==false)
		{
			Project hey=history.get(history.size()-1);
			project.getSourceCodes().clear();
			for(Entry<String, StringBuilder> e:hey.getSourceCodes().entrySet())
			{
				project.getSourceCodes().put(e.getKey(), new StringBuilder(e.getValue()));

			}

			project.setName(hey.getName());
			project.setVersion(hey.getVersion());
			
			history.remove(history.size()-1);
		}
	}
}

Project rms = new Project("Report Management System", 1);
		rms.getSourceCodes().put("A", new StringBuilder("public class Aaaaaaaa"));
		rms.getSourceCodes().put("B", new StringBuilder("public class B"));
		rms.getSourceCodes().put("C", new StringBuilder("finecccccc"));

		VersionControl git = new VersionControl(rms);
		Project snapshot = git.takeSnapshot();
		
		rms.setName("RMS");
		rms.setVersion(2);
		rms.getSourceCodes().get("A").append(" bbbb");
			git.goBack();



 private Map<String,StringBuilder> sourceCodes;        sourceCodes = new HashMap<>();