Inspectopedia
 
2024.3

Magic number

Warning
Last modified: 03 December 2024

Reports "magic numbers": numeric literals that are not named by a constant declaration.

Using magic numbers can lead to unclear code, as well as errors if a magic number is changed in one location but remains unchanged not another. The numbers 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 100, 1000, 0L, 1L, 2L, 0.0, 1.0, 0.0F and 1.0F are not reported by this inspection.

Example:

A quick-fix introduces a new constant:

Configure the inspection:

  • Use the Ignore constants in 'hashCode()' methods option to disable this inspection within hashCode() methods.

  • Use the Ignore in annotations option to ignore magic numbers in annotations.

  • Use the Ignore initial capacity for StringBuilders and Collections option to ignore magic numbers used as initial capacity when constructing Collection, Map, StringBuilder or StringBuffer objects.