That’s all and checks if a string does not consist of a prime number of “1“, e.g. “111” is prime whereas “1111” is not:
Although this seems cryptic its rather straight forward: match on either “” or “1” (first part until “|“) or match on a substring of 2 or more “1” with repeatedly fits the whole. For the string “111111” the substring “11” fits in 3 times.
Over all its a very high level description of a primality test. I never considered regular expressions as a mathematical domain language.
More details on Avinash Meetoo’s Blog.
If you follow the common practice to subclass JLabel to add some formatting to your combobox you will be surprised that this will break the rendering of JComboBoxes in the Nimbus Look Ant Feel.
Basically the nice glass like look of the combobox will disappear and the old flat look will be restored. This comes due to Nimbus using a custom CellRenderer:
javax.swing.plaf.synth.SynthComboBoxUI$SynthComboBoxRenderer
Fortunately this renderer is based on JLabel, too. This is why you can simply wrap the renderer and add some blinkenlights when needed:
The implementation is straight forward:
Use it as follows:
jComboBox.setRenderer(new InstanceWithIconCellRendererWrapper(jComboBox.getRenderer()));