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listA.removeAll(new HashSet(listB));
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List<String> listWithDuplicates = Arrays.asList("A", "B", "A", "C", "B");
List<String> listWithoutDuplicates = new ArrayList<>(new HashSet<>(listWithDuplicates));
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Set<String> set = new HashSet<>(yourList);
yourList.clear();
yourList.addAll(set);