TCHS-7-250

Problem Statement

You are given a String text. Determine the letters (both lowercase and uppercase) that appear in text. Return a String which contains those letters, converted to lowercase, and then sorted in alphabetical order. The returned String should include all occurrences of each letter.

Definition

Class:	TextProcessor
Method:	collectLetters
Parameters:	String
Returns:	String
Method signature:	String collectLetters(String text)
(be sure your method is public)

Constraints

-

text will contain between 1 and 50 characters, inclusive.

-

text will contain only letters ('A'-'Z', 'a'-'z'), digits ('0'-'9'), and spaces (' ').

Examples

0)

"She sells sea shells"

Returns: "aeeeehhllllssssss"

The letters that appear in the input are "shesellsseashells" (converted to lower case and ignoring non-letter characters). Then we sort these letters alphabetically.

1)

"ReMemBEr To IgnoRE CASe"

Returns: "abceeeeegimmnoorrrst"

2)

"12345"

Returns: ""

There are no letters, so the empty String should be returned.

3)

"TopCoder is fun"

Returns: "cdefinooprstu"

4)

"Knights are better than Bishops"

Returns: "aabbeeeghhhiiknnoprrssstttt"

import java.util.*;

public class TextProcessor {

	public static String collectLetters(String text) {
		List<Character> list = new ArrayList<Character>();
		for (int i = 0; i < text.length(); i++) {
			char ch = text.charAt(i);
			if (Character.isLetter(ch)) {
				if (Character.isUpperCase(ch))
					ch = (char) (ch - 'A' + 'a');
				list.add(ch);
			}
		}
		Collections.sort(list);
		StringBuilder sb = new StringBuilder();
		for (int i = 0; i < list.size(); i++)
			sb.append(list.get(i));
		return sb.toString();
	}

}