exercism————Diamonds

題目：

方法一：

static final char[] ALPHABET = {'A','B','C','D','E','F','G','H','I','G','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z'};

	public void printDimond(char letter) {
		if (!alphabetContains(letter)) {throw new InputMismatchException("Invalid input");}
		int times = cycleTimes(letter);
		// The top half of part
		for (int i = 0; i <= times; i++) {
			// print spaces
			for (int j = 0; j < (times - i); j++) {
				System.out.print(" ");
			}
			// print letters
			System.out.print(ALPHABET[i]);
			// print spaces
			for (int j = 0; j < (2 * i - 1); j++) {
				System.out.print(" ");
			}
			// print letters
			if (i == 0) { System.out.println();}
			else {System.out.println(ALPHABET[i]);}
		}

		// The bottom half of part
		for (int i = 0; i < times; i++) {
			// print spaces
			for (int j = 0; j < (i + 1); j++) {
				System.out.print(" ");
			}
			// print letters
			System.out.print(ALPHABET[times - i - 1]);
			// print spaces
			for (int j = 0; j < (2 * (times - i) - 3); j++) {
				System.out.print(" ");
			}
			// print letters
			if (i == (times - 1)) { System.out.println(); }
			else { System.out.println(ALPHABET[times - i - 1]); }

方法二：

	private static final char START_CHAR = 'A';

	 List<String> printToList(char endChar) {

		List<String> result = new ArrayList<>();

		for (char c = START_CHAR; c < endChar; c++) {
			result.add(getLine(c, endChar));
		}

		for (char c = endChar; c >= START_CHAR; c--) {
			result.add(getLine(c, endChar));
		}

		return result;
	}

	private String getLine(char c, char endChar) {
		int lineLength = (endChar - START_CHAR) * 2 + 1;

		char[] line = new char[lineLength];
		for (int i = 0; i < lineLength; i++) {
			line[i] = ' ';
		}

		line[endChar - c] = c;
		line[endChar + c - 2 * START_CHAR] = c;

		return String.valueOf(line);
	}

Conclusion:

方法一：運用大量for迴圈，程式碼可讀性較差
方法二：思路奇特，通過把每行儲存在List中，最後用Iterator列印出來
有很多值得學習的地方：

1. for迴圈中引入char,簡便易懂。以後可以利用起來
2. 充分利用陣列特性，先將陣列所有元素代替為" "，再找每個字母在陣列中位置的關係來填充陣列，簡單明瞭，易於理解，nice code!