Java .compareToIgnoreCase()

The compareToIgnoreCase() method compares two strings lexicographically based on the Unicode value of each character in the string while ignoring lower case and upper case differences.

A value of 0 will be returned if equal to comparison, less than 0 if the string is lexicographically less, and greater than 0 if the string is lexicographically greater.

Syntax

stringA.compareToIgnoreCase(stringB);

Both stringA and stringB are required in order for the .compareTo() method to work properly.

A value of 0 will be returned if the strings are equal. Otherwise, the following will happen:

• A number less than 0 is returned if stringA is lexicographically less than stringB.
• A number greater than 0 is returned if stringA is lexicographically more than stringB.

Through the CASE_INSENSITIVE_ORDER field of the String class, upper and lower case characters effectively hold the same Unicode value (e.g., “a” - “A” = 0).

Note: To take case into account, the .compareTo() method should be used. Alternatively, the .equals() method can be used to compare strings without taking Unicode values into account.

Example 1

Compare "Codecademy" to "Codecademy":

class CompareStringsIgnoreCase {
  public static void main(String[] args) {
    String word1 = "Codecademy";
    String word2 = "Codecademy";

    System.out.println(word1.compareToIgnoreCase(word2));
    // Output: 0
  }
}

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Example 2

Compare "Codecademy" to "codecademy":

class CompareStringsIgnoreCase {
  public static void main(String[] args) {
    String word1 = "Codecademy";
    String word2 = "codecademy";

    System.out.println(word1.compareToIgnoreCase(word2));
    // Output: 0
  }
}

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