In this example we will generate random lowercase letter by using ASCII representation of lowercase letter. The ASCII range for lowercase letters is between 97 and 126 so we can generate a random number within a range then convert the converting ASCII char to a string. We will output the lower case letter by using a java 8 foreach loop.
Java 8
@Test
public void random_lowercase_java8() {
Random random = new Random();
random.ints(97, 126).limit(10)
.forEach(a -> System.out.println(Character.toString((char) a)));
}