find-the-levenshtein-distance-between-two-strings.md

Find the Levenshtein distance between two Strings

Sometimes when comparing Strings you want a certain degree of flexibility when looking for matches due to typos, different spellings etc, you can easily achieve this by using Apache Commons and its handy StringUtils.getLevenshteinDistance. This method returns the distance between two Strings as to how much they differ, examples below:

import java.util.Arrays;

import org.apache.commons.lang3.StringUtils;

public enum NAMES {

	OWEN("Owen"), //
	HOLLIE("Hollie");

	private String name;

	private NAMES(String name) {
		this.name = name;
	}

	public static NAMES find(String name,int threshold) {
		return Arrays.stream(values())
				.filter(n -> StringUtils.getLevenshteinDistance(n.name, name) < threshold)
				.findFirst()
				.orElseThrow(() -> new IllegalArgumentException("NAME: " + name + " not found"));
	}

}

Then the subsequent tests of the above, by increasing the threshold we can make matching less rigid:

	@Test
	public void shouldFindNameWithExactMatch() {
		val name = "Owen";
		val threshold = 1;
		assertThat(NAMES.find(name,threshold)).isEqualTo(NAMES.OWEN);
	}
	
	@Test(expected = IllegalArgumentException.class) 
	public void shouldNotFindNameViaLevenshteinMatch() {
		val name = "Holly";
		val threshold = 1;
		NAMES.find(name, threshold);
	}
	
	@Test() 
	public void shouldFindNameViaLevenshteinMatch() {
		val name = "Holly";
		val threshold = 3;
		assertThat(NAMES.find(name, threshold)).isEqualTo(NAMES.HOLLIE);
	}