Change a single icon in the Unity launcher panel?

Question

I have a third-party application, (in this case, Oracle SQLDeveloper which is a java application), that I installed manually (i.e. not through apt). When I ran it, I selected to "Lock to Launcher" so I can easily launch it again. The icon works to launch the application, but the icon is a generic grey question mark icon. I can download various other icons that would be more appropriate, but I don't see any way to customize just a single icon in the launcher.

Solution

From your comment, it turns out that there is no icon defined in the .desktop file. You can use an icon "of your choice", and edit the line:

Icon=.png

to:

Icon=/path/to/your/icon.png

You will possibly have to log out and back in to make the change appear.

Note1

If you found your .desktop file in /usr/share/applications, it is good practice to first copy it to ~/.local/share/applications and edit the local copy. After log out / in, the local version will "overrule" the one in /usr/share/applications.

Both Dash and the Unity Launcher will then use the local one.

Note2

You might want to look inside the application's directory (which seems to be /opt/sqldeveloper) if there is not already an appropriate icon to use. /opt is a typical directory where self-contained "all in one" applications can be located.

Comments

[Jacob Vlijm]

please look inside your ~/.local/share/applications folder to see if there is a representing .desktop file of the application. (If not, look in /usr/share/applications) If so, could you open it with gedit (drag it over a gedit window) and post the line starting with Icon= (or better: the whole file). There can be various reasons why an icon does not appear properly in the launcher.

[Aphoid]

[Desktop Entry] Encoding=UTF-8 Version=1.0 Type=Application Name=Oracle SQL Developer Icon=.png Path=/opt/sqldeveloper/sqldeveloper/bin Exec=/usr/lib/jvm/java-7-openjdk-amd64/bin/java .....

[Aphoid]

Should I be able to directly edit the "Icon=.png" line? If so, how do I update it and/or make it stick?

[Aphoid]

It turned out that I had it in .local and when I updated the Icon=/opt/sqldeveloper/icon.png, it showed up instantly without logging out.