Merge "Support varargs for concatElements" (c71fb23b) · Commits · e / os / android_frameworks_base

core/java/com/android/internal/util/ArrayUtils.java

+52 −12

Original line number	Diff line number	Diff line
		@@ -320,22 +320,62 @@ public class ArrayUtils {
		return array;
		}

		/**
		* Combine multiple arrays into a single array.
		*
		* @param kind The class of the array elements
		* @param arrays The arrays to combine
		* @param <T> The class of the array elements (inferred from kind).
		* @return A single array containing all the elements of the parameter arrays.
		*/
		@SuppressWarnings("unchecked")
		public static @NonNull <T> T[] concatElements(Class<T> kind, @Nullable T[] a, @Nullable T[] b) {
		final int an = (a != null) ? a.length : 0;
		final int bn = (b != null) ? b.length : 0;
		if (an == 0 && bn == 0) {
		public static @NonNull <T> T[] concatElements(Class<T> kind, @Nullable T[]... arrays) {
		if (arrays == null \|\| arrays.length == 0) {
		return createEmptyArray(kind);
		}

		int totalLength = 0;
		int maxLength = 0;
		T[] maxLengthArray = arrays[0];
		for (T[] item : arrays) {
		if (item == null) {
		continue;
		}

		totalLength += item.length;
		if (item.length > maxLength) {
		maxLengthArray = item;
		maxLength = item.length;
		}
		}

		// Optimization for entirely empty arrays.
		if (totalLength == 0) {
		return createEmptyArray(kind);
		}

		final T[] all = (T[]) Array.newInstance(kind, totalLength);
		int pos = 0;
		for (T[] item : arrays) {
		if (item == null \|\| item.length == 0) {
		continue;
		}
		System.arraycopy(item, 0, all, pos, item.length);
		pos += item.length;
		}
		return all;
		}

		private static @NonNull <T> T[] createEmptyArray(Class<T> kind) {
		if (kind == String.class) {
		return (T[]) EmptyArray.STRING;
		} else if (kind == Object.class) {
		return (T[]) EmptyArray.OBJECT;
		}

		return (T[]) Array.newInstance(kind, 0);
		}
		final T[] res = (T[]) Array.newInstance(kind, an + bn);
		if (an > 0) System.arraycopy(a, 0, res, 0, an);
		if (bn > 0) System.arraycopy(b, 0, res, an, bn);
		return res;
		}


		/**
		* Adds value to given array if not already present, providing set-like

core/tests/utiltests/src/com/android/internal/util/ArrayUtilsTest.java

+36 −0

Original line number	Diff line number	Diff line
		@@ -177,4 +177,40 @@ public class ArrayUtilsTest extends TestCase {
		assertArrayEquals(new Long[] { 1L, 2L, 3L, 4L },
		concatElements(Long.class, new Long[] { 1L, 2L }, new Long[] { 3L, 4L }));
		}

		public void testConcatElements_threeWay() {
		String[] array1 = { "1", "2" };
		String[] array2 = { "3", "4" };
		String[] array3 = { "5", "6" };
		String[] expectation = {"1", "2", "3", "4", "5", "6"};

		String[] concatResult = ArrayUtils.concatElements(String.class, array1, array2, array3);
		assertArrayEquals(expectation, concatResult);
		}


		public void testConcatElements_threeWayWithNull() {
		String[] array1 = { "1", "2" };
		String[] array2 = null;
		String[] array3 = { "5", "6" };
		String[] expectation = {"1", "2", "5", "6"};

		String[] concatResult = ArrayUtils.concatElements(String.class, array1, array2, array3);
		assertArrayEquals(expectation, concatResult);
		}

		public void testConcatElements_zeroElements() {
		String[] expectation = new String[0];

		String[] concatResult = ArrayUtils.concatElements(String.class);
		assertArrayEquals(expectation, concatResult);
		}

		public void testConcatElements_oneNullElement() {
		String[] expectation = new String[0];

		String[] concatResult = ArrayUtils.concatElements(String.class, null);
		assertArrayEquals(expectation, concatResult);
		}

		}