Why git keeps showing my changes when I switch branches (modified,added, deleted files) no matter if I run git add or not?

Question

I'm really new to git and I've been trying to understand why git keeps showing whatever I changed in one branch in another branch when I run git checkout to switch between branches First I tried not using git add and didn't work. However, I tried then using git add, but didn't fix the problem. I'm not using git commit yet.

This is basically what I'm doing:

$ git clone <a_repository>  
$ git branch  
* master  
$ git branch testing  
$ git checkout testing  
...edit a file, add a new one, delete...  
$ git status  
    # On branch testing  
    # Changed but not updated:  
    #   (use "git add/rm <file>..." to update what will be committed)  
    #   (use "git checkout -- <file>..." to discard changes in working directory)  
    #  
    #       deleted:    file1.txt  
    #  
    # Untracked files:  
    #   (use "git add <file>..." to include in what will be committed)  
    #  
    #       file2.txt  
no changes added to commit (use "git add" and/or "git commit -a")  
$ git branch  
  master  
* testing  
$ git checkout master  
D       file1.txt  
Switched to branch 'master'  
$ git status  
    # On branch master  
    # Changed but not updated:  
    #   (use "git add/rm <file>..." to update what will be committed)  
    #   (use "git checkout -- <file>..." to discard changes in working directory)  
    #  
    #       deleted:    file1.txt  
    #  
    # Untracked files:  
    #   (use "git add <file>..." to include in what will be committed)  
    #  
    #       file2.txt  
no changes added to commit (use "git add" and/or "git commit -a")  

I thought that, while using branches, whatever you do in one branch, it's invisible to all the other branches. Is not that the reason of creating branches?

I tried using "git add" but the changes are visible in both branches. Do I need to run "git commit" before switching between branches to avoid this?

Answer 1

Switching branches carries uncommitted changes with you. Either commit first, run git checkout . to undo them, or run git stash before switching. (You can get your changes back with git stash apply)