Repository: commons-lang Updated Branches: refs/heads/master 09ef69c5b -> 87937b2e7
[LANG-1290] StringUtils.join() with support for List<?> with configurable start/end indices. Project: http://git-wip-us.apache.org/repos/asf/commons-lang/repo Commit: http://git-wip-us.apache.org/repos/asf/commons-lang/commit/87937b2e Tree: http://git-wip-us.apache.org/repos/asf/commons-lang/tree/87937b2e Diff: http://git-wip-us.apache.org/repos/asf/commons-lang/diff/87937b2e Branch: refs/heads/master Commit: 87937b2e7192524306aa58d74c90537eec997cfa Parents: 09ef69c Author: Jochen Schalanda <joc...@schalanda.name> Authored: Tue May 22 08:40:55 2018 -0600 Committer: Gary Gregory <garydgreg...@gmail.com> Committed: Tue May 22 08:40:55 2018 -0600 ---------------------------------------------------------------------- .../org/apache/commons/lang3/StringUtils.java | 76 ++++++++++++++++++++ .../apache/commons/lang3/StringUtilsTest.java | 38 ++++++++++ 2 files changed, 114 insertions(+) ---------------------------------------------------------------------- http://git-wip-us.apache.org/repos/asf/commons-lang/blob/87937b2e/src/main/java/org/apache/commons/lang3/StringUtils.java ---------------------------------------------------------------------- diff --git a/src/main/java/org/apache/commons/lang3/StringUtils.java b/src/main/java/org/apache/commons/lang3/StringUtils.java index 495e4ec..9387376 100644 --- a/src/main/java/org/apache/commons/lang3/StringUtils.java +++ b/src/main/java/org/apache/commons/lang3/StringUtils.java @@ -4722,6 +4722,82 @@ public class StringUtils { } /** + * <p>Joins the elements of the provided {@code List} into a single String + * containing the provided list of elements.</p> + * + * <p>No delimiter is added before or after the list. + * Null objects or empty strings within the array are represented by + * empty strings.</p> + * + * <pre> + * StringUtils.join(null, *) = null + * StringUtils.join([], *) = "" + * StringUtils.join([null], *) = "" + * StringUtils.join(["a", "b", "c"], ';') = "a;b;c" + * StringUtils.join(["a", "b", "c"], null) = "abc" + * StringUtils.join([null, "", "a"], ';') = ";;a" + * </pre> + * + * @param list the {@code List} of values to join together, may be null + * @param separator the separator character to use + * @param startIndex the first index to start joining from. It is + * an error to pass in an end index past the end of the list + * @param endIndex the index to stop joining from (exclusive). It is + * an error to pass in an end index past the end of the list + * @return the joined String, {@code null} if null list input + * @since 3.8 + */ + public static String join(final List<?> list, final char separator, final int startIndex, final int endIndex) { + if (list == null) { + return null; + } + final int noOfItems = endIndex - startIndex; + if (noOfItems <= 0) { + return EMPTY; + } + final List<?> subList = list.subList(startIndex, endIndex); + return join(subList.iterator(), separator); + } + + /** + * <p>Joins the elements of the provided {@code List} into a single String + * containing the provided list of elements.</p> + * + * <p>No delimiter is added before or after the list. + * Null objects or empty strings within the array are represented by + * empty strings.</p> + * + * <pre> + * StringUtils.join(null, *) = null + * StringUtils.join([], *) = "" + * StringUtils.join([null], *) = "" + * StringUtils.join(["a", "b", "c"], ';') = "a;b;c" + * StringUtils.join(["a", "b", "c"], null) = "abc" + * StringUtils.join([null, "", "a"], ';') = ";;a" + * </pre> + * + * @param list the {@code List} of values to join together, may be null + * @param separator the separator character to use + * @param startIndex the first index to start joining from. It is + * an error to pass in an end index past the end of the list + * @param endIndex the index to stop joining from (exclusive). It is + * an error to pass in an end index past the end of the list + * @return the joined String, {@code null} if null list input + * @since 3.8 + */ + public static String join(final List<?> list, final String separator, final int startIndex, final int endIndex) { + if (list == null) { + return null; + } + final int noOfItems = endIndex - startIndex; + if (noOfItems <= 0) { + return EMPTY; + } + final List<?> subList = list.subList(startIndex, endIndex); + return join(subList.iterator(), separator); + } + + /** * <p>Joins the elements of the provided varargs into a * single String containing the provided elements.</p> * http://git-wip-us.apache.org/repos/asf/commons-lang/blob/87937b2e/src/test/java/org/apache/commons/lang3/StringUtilsTest.java ---------------------------------------------------------------------- diff --git a/src/test/java/org/apache/commons/lang3/StringUtilsTest.java b/src/test/java/org/apache/commons/lang3/StringUtilsTest.java index c4299b8..ee3beeb 100644 --- a/src/test/java/org/apache/commons/lang3/StringUtilsTest.java +++ b/src/test/java/org/apache/commons/lang3/StringUtilsTest.java @@ -34,6 +34,7 @@ import java.nio.charset.Charset; import java.util.Arrays; import java.util.Collections; import java.util.Iterator; +import java.util.List; import java.util.Locale; import java.util.Objects; import java.util.regex.PatternSyntaxException; @@ -100,6 +101,11 @@ public class StringUtilsTest { private static final char[] CHAR_PRIM_LIST = {'1', '2'}; private static final float[] FLOAT_PRIM_LIST = {1, 2}; private static final double[] DOUBLE_PRIM_LIST = {1, 2}; + private static final List<String> MIXED_STRING_LIST = Arrays.asList(null, "", "foo"); + private static final List<Object> MIXED_TYPE_OBJECT_LIST = Arrays.<Object>asList("foo", Long.valueOf(2L)); + private static final List<String> STRING_LIST = Arrays.asList("foo", "bar", "baz"); + private static final List<String> EMPTY_STRING_LIST = Collections.emptyList(); + private static final List<String> NULL_STRING_LIST = Collections.singletonList(null); private static final String SEPARATOR = ","; private static final char SEPARATOR_CHAR = ';'; @@ -367,6 +373,38 @@ public class StringUtilsTest { } @Test + public void testJoin_List() { + assertNull(StringUtils.join((List<String>) null, null)); + assertEquals(TEXT_LIST_NOSEP, StringUtils.join(STRING_LIST, null)); + assertEquals(TEXT_LIST_NOSEP, StringUtils.join(STRING_LIST, "")); + + assertEquals("", StringUtils.join(NULL_STRING_LIST, null)); + + assertEquals("", StringUtils.join(EMPTY_STRING_LIST, null)); + assertEquals("", StringUtils.join(EMPTY_STRING_LIST, "")); + assertEquals("", StringUtils.join(EMPTY_STRING_LIST, SEPARATOR)); + + assertEquals(TEXT_LIST, StringUtils.join(STRING_LIST, SEPARATOR)); + assertEquals(",,foo", StringUtils.join(MIXED_STRING_LIST, SEPARATOR)); + assertEquals("foo,2", StringUtils.join(MIXED_TYPE_OBJECT_LIST, SEPARATOR)); + + assertEquals("/", StringUtils.join(MIXED_STRING_LIST, "/", 0, MIXED_STRING_LIST.size() - 1)); + assertEquals("", StringUtils.join(MIXED_STRING_LIST, "", 0, MIXED_STRING_LIST.size()- 1)); + assertEquals("foo", StringUtils.join(MIXED_TYPE_OBJECT_LIST, "/", 0, 1)); + assertEquals("foo/2", StringUtils.join(MIXED_TYPE_OBJECT_LIST, "/", 0, 2)); + assertEquals("2", StringUtils.join(MIXED_TYPE_OBJECT_LIST, "/", 1, 2)); + assertEquals("", StringUtils.join(MIXED_TYPE_OBJECT_LIST, "/", 2, 1)); + assertNull(null, StringUtils.join((List) null, "/", 0, 1)); + + assertEquals("/", StringUtils.join(MIXED_STRING_LIST, '/', 0, MIXED_STRING_LIST.size() - 1)); + assertEquals("foo", StringUtils.join(MIXED_TYPE_OBJECT_LIST, '/', 0, 1)); + assertEquals("foo/2", StringUtils.join(MIXED_TYPE_OBJECT_LIST, '/', 0, 2)); + assertEquals("2", StringUtils.join(MIXED_TYPE_OBJECT_LIST, '/', 1, 2)); + assertEquals("", StringUtils.join(MIXED_TYPE_OBJECT_LIST, '/', 2, 1)); + assertNull(null, StringUtils.join((List) null, '/', 0, 1)); + } + + @Test public void testJoin_IteratorChar() { assertNull(StringUtils.join((Iterator<?>) null, ',')); assertEquals(TEXT_LIST_CHAR, StringUtils.join(Arrays.asList(ARRAY_LIST).iterator(), SEPARATOR_CHAR));
