Gruppe 4

src/main/java/de/cas/mse/exercise/diamond/Diamond.java

@@ -4,28 +4,51 @@
 
 public class Diamond {
 
-	public String print(int n) {
-		if (n <= 0 || n % 2 == 0) {
+	private static final char LINEBREAK = '\n';
+	private static final char FILLER = '*';
+	private static final char BLANK = ' ';
+
+	public String getFromSize(int maxSize) {
+		if (isInvalidSize(maxSize)) {
 			return null;
 		}
-		StringBuilder builder = new StringBuilder(new String(make(n, n)));
-		for (int i = n - 2; i > 0; i -= 2) {
-			char[] chars = make(n, i);
-			builder.insert(0, chars);
-			builder.append(chars);
+		return createDiamond(maxSize);
+	}
+
+	private String createDiamond(int maxSize) {
+		StringBuilder builder = new StringBuilder();
+		for (int i = 0; i < maxSize; i++) {
+			builder.append(getDiamondLine(maxSize, getLineSize(i, maxSize)));
 		}
 		return builder.toString();
 	}
 
-	private char[] make(int i, int j) {
-		int amount = ((i - j) / 2);
-		char[] chars = new char[amount + j + 1];
-		if (amount > 0) {
-			Arrays.fill(chars, 0, amount, ' ');
+	private int getLineSize(int lineIndex, int maxSize) {
+		if (isLineOnUpperSide(lineIndex, maxSize)) {
+			return lineIndex * 2 + 1;
 		}
-		Arrays.fill(chars, amount, amount + j, '*');
-		chars[chars.length - 1] = '\n';
+		return (maxSize - lineIndex - 1) * 2 + 1;
+	}
+
+	private boolean isLineOnUpperSide(int lineIndex, int maxSize) {
+		return lineIndex <= maxSize / 2;
+	}
+
+	private boolean isInvalidSize(int n) {
+		return n <= 0 || n % 2 == 0;
+	}
+
+	private char[] getDiamondLine(int maxSize, int lineSize) {
+		int whiteSpaceCount = getWhiteSpaceCount(maxSize, lineSize);
+		char[] chars = new char[whiteSpaceCount + lineSize + 1];
+		Arrays.fill(chars, 0, whiteSpaceCount, BLANK);
+		Arrays.fill(chars, whiteSpaceCount, whiteSpaceCount + lineSize, FILLER);
+		chars[chars.length - 1] = LINEBREAK;
 		return chars;
 	}
 
+	private int getWhiteSpaceCount(int maxSize, int lineSize) {
+		return (maxSize - lineSize) / 2;
+	}
+
 }

src/test/java/de/cas/mse/exercise/diamond/DiamondTest.java

@@ -13,7 +13,7 @@ public void diamond3_shouldPrint() {
 		expected.append("***\n");
 		expected.append(" *\n");
 
-		String actual = new Diamond().print(3);
+		String actual = new Diamond().getFromSize(3);
 		assertEquals(expected.toString(), actual);
 		System.out.println(actual);
 	}
@@ -27,23 +27,23 @@ public void diamond5_shouldPrint() {
 		expected.append(" ***\n");
 		expected.append("  *\n");
 
-		String actual = new Diamond().print(5);
+		String actual = new Diamond().getFromSize(5);
 		assertEquals(expected.toString(), actual);
 		System.out.println(actual);
 	}
 
 	@Test
 	public void diamond0_shouldReturnNull() {
-		assertEquals(null, new Diamond().print(0));
+		assertEquals(null, new Diamond().getFromSize(0));
 	}
 
 	@Test
 	public void diamondNegative_shouldReturnNull() {
-		assertEquals(null, new Diamond().print(-1));
+		assertEquals(null, new Diamond().getFromSize(-1));
 	}
 
 	@Test
 	public void diamondEven_shouldReturnNull() {
-		assertEquals(null, new Diamond().print(10));
+		assertEquals(null, new Diamond().getFromSize(10));
 	}
 }