Refer JAR files in classpath using command > javac -classpath commons-text-1.9.jar:commons-lang3-3.0.1.jar:. Main.java > java -classpath commons-text-1.9.jar:commons-lang3-3.0.1.jar:. Main import org.apache.commons.text.diff.StringsComparator; import org.apache.commons.text.diff.EditScript; import org.apache.commons.lang3.StringUtils; public class Main { public static void main(String arg[]) { StringsComparator cmp = new StringsComparator("ABCFGH", "BCDEFG"); EditScript<Character> script = cmp.getScript(); int mod = script.getModifications(); System.out.println(mod); System.out.println(StringUtils.isAlpha("abc123")); } }