am ed575b62: Merge "Add documentation for CollectionUtils#arrayAsList"

* commit 'ed575b62da197e81ace23eeb1af09fd776fa0b41':
  Add documentation for CollectionUtils#arrayAsList
main
Ken Wakasa 2014-10-31 07:09:52 +00:00 committed by Android Git Automerger
commit ae9bfdc061
2 changed files with 44 additions and 2 deletions

View File

@ -22,16 +22,27 @@ import java.util.Collection;
import javax.annotation.Nonnull;
import javax.annotation.Nullable;
/**
* Utility methods for working with collections.
*/
public final class CollectionUtils {
private CollectionUtils() {
// This utility class is not publicly instantiable.
}
/**
* Converts a sub-range of the given array to an ArrayList of the appropriate type.
* @param array Array to be converted.
* @param start First index inclusive to be converted.
* @param end Last index exclusive to be converted.
* @throws IllegalArgumentException if start or end are out of range or start > end.
*/
@Nonnull
public static <E> ArrayList<E> arrayAsList(@Nonnull final E[] array, final int start,
final int end) {
if (start < 0 || start > end || end > array.length) {
throw new IllegalArgumentException();
throw new IllegalArgumentException("Invalid start: " + start + " end: " + end
+ " with array.length: " + array.length);
}
final ArrayList<E> list = new ArrayList<>(end - start);

View File

@ -28,15 +28,46 @@ import java.util.Collections;
*/
@SmallTest
public class CollectionUtilsTests extends AndroidTestCase {
/**
* Tests that {@link CollectionUtils#arrayAsList(Object[],int,int)} fails as expected
* with some invalid inputs.
*/
public void testArrayAsListFailure() {
final String[] array = { "0", "1" };
// Negative start
try {
CollectionUtils.arrayAsList(array, -1, 1);
fail("Failed to catch start < 0");
} catch (final IllegalArgumentException e) {
assertEquals("Invalid start: -1 end: 1 with array.length: 2", e.getMessage());
}
// start > end
try {
CollectionUtils.arrayAsList(array, 1, -1);
fail("Failed to catch start > end");
} catch (final IllegalArgumentException e) {
assertEquals("Invalid start: 1 end: -1 with array.length: 2", e.getMessage());
}
// end > array.length
try {
CollectionUtils.arrayAsList(array, 1, 3);
fail("Failed to catch end > array.length");
} catch (final IllegalArgumentException e) {
assertEquals("Invalid start: 1 end: 3 with array.length: 2", e.getMessage());
}
}
/**
* Tests that {@link CollectionUtils#arrayAsList(Object[],int,int)} gives the expected
* results for a few valid inputs.
*/
public void testArrayAsList() {
final String[] array = { "0", "1", "2", "3", "4" };
final ArrayList<String> empty = new ArrayList<>();
assertEquals(empty, CollectionUtils.arrayAsList(new String[] { }, 0, 0));
final String[] array = { "0", "1", "2", "3", "4" };
assertEquals(empty, CollectionUtils.arrayAsList(array, 0, 0));
assertEquals(empty, CollectionUtils.arrayAsList(array, 1, 1));
assertEquals(empty, CollectionUtils.arrayAsList(array, array.length, array.length));
final ArrayList<String> expected123 = new ArrayList<>(Arrays.asList("1", "2", "3"));
assertEquals(expected123, CollectionUtils.arrayAsList(array, 1, 4));
}