How do I view different representations of integers in the Eclipse watch window?

You can do this from Window->Preferences.

For primitives, browse to Java->Debug->Primitive Display Options

Here there is a checkbox for ‘Display Hexadecimal values’. Check this, and you will see both decimal & hexadecimal representations for primitives in the ‘value’ column under Variables view when debugging.

For objects (Integer, Long, etc), browse to Java->Debug->Detail Formatters

For each type you care about, create a detail formatter that formats the value how you like. For java.lang.Integer, you could use the detail formatter: Integer.toHexString(this)

Make sure your detail formatter is enabled, and you should see the hexadecimal representation in the ‘details’ area when you select a variable from the Variables view.