Fix Utils.nonEmptyAndNullJoin

When using the index here, it the index needs to be decremented once an element is removed. To cirecumvent this, the native Collections.removeIf() method is used.

Author: TobiGr

extractor/src/main/java/org/schabi/newpipe/extractor/utils/Utils.java

@@ -274,14 +274,9 @@ public static String join(final String delimiter, final String mapJoin,
     /**
      * Concatenate all non-null, non-empty and strings which are not equal to <code>"null"</code>.
      */
-    public static String nonEmptyAndNullJoin(final String delimiter, final String[] elements) {
-        final List<String> list = Arrays.asList(elements);
-        for (int i = list.size() - 1; i >= 0; i--) {
-            if (isNullOrEmpty(list.get(i)) || list.get(i).equals("null")) {
-                list.remove(i);
-            }
-        }
-
+    public static String nonEmptyAndNullJoin(final CharSequence delimiter, final String[] elements) {
+        final List<String> list = new java.util.ArrayList<>(Arrays.asList(elements));
+        list.removeIf(s -> isNullOrEmpty(s) || s.equals("null"));
         return join(delimiter, list);
     }
 }

extractor/src/test/java/org/schabi/newpipe/extractor/utils/UtilsTest.java

@@ -20,6 +20,7 @@ public void testMixedNumberWordToLong() throws ParsingException {
     @Test
     public void testJoin() {
         assertEquals("some,random,stuff", Utils.join(",", Arrays.asList("some", "random", "stuff")));
+        assertEquals("some,random,not-null,stuff", Utils.nonEmptyAndNullJoin(",", new String[]{"some", "null", "random", "", "not-null", null, "stuff"}));
     }
 
     @Test