Block cursor for Eclipse

Short answer: no

Long:

From comments, OP clarified that the question was about Eclipse. The clue that the question was about the application's cursor (displayed as a part of the graphics within the window) rather than the desktop cursor was the comment about the blinking bar. Desktop cursor themes do not blink, and rarely are just a bar.

If Eclipse supported a change of cursor shape, that would be in one of the Preferences tabs, e.g., for the editor. OP does not find it there.

Web searches for the cursor shape in Eclipse only find comments that the shape is determined by whether you are in insert- or replace-mode. Seeing that, it appears that Eclipse does not allow this feature to be user-customized.

In a check with OSX, I see a feature in

• General
• Editors
• Text Editors
• Accessibility

as Use Custom Caret and Enable thick caret, which are both checked by default. But there is no check-box for blink.