Work on branches in parallelIn this exercise you learn how you can efficiently work in different branches in parallel. A common situation is that you want to switch to another branch and you want to temporarily save your work on the current branch. You will learn two possibilities:

● Amend: Commit an unfinished change and replace this commit later with a new, refined commit using the amend feature of git.

● Stash: Put your change into the git stash area with the stash command

PreparationFollow exercise 2, “Develop a feature/bug fix” to create a commit on a feature branch based on the remote tracking branch origin/master.

Start working on another feature● Create a new local branch based on the remote tracking branch “origin/master”● You may create the new branch from the History View :

○ Select the project, then click Show In > History (Some views, e.g. in the Java EE-Perspective, do not have this shortcut, in this case use Team > Show in History)

○ In the history view click all toggle buttons as shown in the screenshot(“Link with Editor and Selection”, “Show all changes in Repository”, “Compare Mode”, “Show all branches”)

○

Click “Create Branch...” on the commit where“origin/master” points to

● Or you may do that from the Repositories View :select the remote tracking branch origin/master and click Create Branch

● Enter “addMultiplyOperation” as the name of the new branch, make sure the “Checkout new branch” is selected and click Finish

● Check that now you don’t see the changes of the first exercise anymore in your workspace.

● Start working on a change, e.g. add a MultiplyOperation, do not commit yet, first read on.

Save your work temporarilyNow you want to switch to another branch but you want to continue working at your new feature later on. There are two ways to achieve that: doing a preliminary commit and use amend later to continue your work or use stash. You may do this exercise twice to try both ways.

Preliminary CommitThe easiest thing to do is to just commit your work in progress and amend that commit later to replace the preliminary commit.

● Open the Git Staging View● Enter a preliminary message, e.g. “WIP ...” for Work in Progress, stage the files to be

committed and click on Commit

StashSelect Stash Changes on the repository node in the Git Repositories View. As a result you will get a new node in the view. It contains a list of all the stashed changes. The label contains the current branch, the id and the commit message of the current commit.

Note that untracked files are not stashed by default. If you are using at least EGit 3.4 you can include untracked files by checking the corresponding option.

In older versions you have to drag and drop an untracked file to the “Staged Changes” area before you can stash it.

Switch to another branch● Now you can switch to the first feature branch “addDivideOperation”, either by double

clicking on the branch node in the Git Repositories View, by selecting “Team > Switch to > addDivideOperation” or by clicking “Checkout” in the History View.

● Check that your workspace contains the changes you committed in your first feature (implementing divide) branch. You could now continue working here. For example: you may want to fix the division by zero issue if it is not already handled. If you do any changes in the “addDivideOperation” branch don’t forget to commit them before the next step

● Switch back to the “addMultiplyOperation” branch

Continue working on the branch to add MultiplyCase 1: Preliminary Commit

● Do another change in the workspace improving Multiply.● Compare your changed project with the first, preliminary commit by selecting

Compare With > HEAD revision. This will show you the changes you will add on top of the first commit.

● Compare your changed project with the parent commit of your first, preliminary commit by selecting Compare With > Previous revision. This will show you the changes you will have in your new commit after the next step.

Create a new commit with the combined changes of your first, preliminary commit and your current changes

● Open the Git Staging View ● Click the “Amend” button as shown below.

● Now you see again the commit message of the last commit you made in this branch. Change it to something meaningful, stage the change and click the Commit button.

● In the History View you can now see that your first, preliminary commit was replaced by the new one.

Case 2: Stash● In the Repositories View, select Apply Stashed Changes on the stash entry.

● Note that you can apply the stashed change on any commit in your repository. This is useful if you have started on a branch but you realize that you would like to continue on another branch. If you apply the stashed commit on another base version this may lead to conflicts you may have to resolve in this case.

Copyright © 2014 by C. Halstrick, E. Kempin, S. Lay, S. Zivkov, M. Sohn