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Call to 'String.toUpperCase()' or 'toLowerCase()' without locale

Reports toUpperCase() or toLowerCase() calls on String objects that do not specify a java.util.Locale. In these cases the default system locale is used, which can cause problems in an internationalized environment.

For example the code "i".toUpperCase().equals("I") returns false in the Turkish and Azerbaijani locales, where the dotted and dotless 'i' are separate letters. Calling toUpperCase() on an English string containing an 'i', when running in a Turkish locale, will return incorrect results. Alternatively, when dealing with strings that should be treated as locale-independent, like HTML tags, this can lead to errors.

Inspection Details

Available in:

IntelliJ IDEA 2023.3, Qodana for JVM 2023.3


Java, 233.SNAPSHOT

Last modified: 13 July 2023