TreeMultimap doesn't allow null or empty values?

Question

I want duplicate values + natural order + empty, which collection support these features?

I have tried Multihashmap and TreeMultimap. Treemultimap didn't allow empty values, even I have key, but its allowing...

public static void main(String[] args) { 
    TreeMultimap<String, String> mp = TreeMultimap.create();
    StringBuilder b = new StringBuilder();
    mp.put("a", "10"); 
    mp.put("a", "11"); 
    mp.put("a", "12"); 
    mp.put("b", "13"); 
    mp.put("c", "14"); 
    mp.put("e", "");
    mp.put("b", "1");
    mp.put("b", "2");
    mp.put("b", "3");
    List list = null; 
    for(String key : mp.keySet())  
    {
        System.out.println("mp.values()"+mp.values());
        int itemcount = mp.size();
        System.out.println(itemcount);

    }

expected output format as

Why did you tag this with [tag:oracle] and [tag:sql]? If there's some relation to these tags, please mention it in the text. Otherwise they don't apply. — Joachim Sauer, Jun 03 '13 at 05:22
I'm just wondering , last 3 hours i didn't get any feedback.But normally responses are very fast in stackoverflow. — user2444474, Jun 03 '13 at 05:22
So that's why you add unrelated tags to get some more input? That's an abuse of the system. Instead, try to update your question with additional findings or details (for example, what's the *actual* output of your code?) — Joachim Sauer, Jun 03 '13 at 05:24
Yes, front layer looks very hard to achive this scenrio.Thats reason i would have added sql, to get resultset sa above format. — user2444474, Jun 03 '13 at 05:24
Possible duplicate of [Adding a key with an empty value to Guava Multimap](http://stackoverflow.com/questions/11587895/adding-a-key-with-an-empty-value-to-guava-multimap) — amaidment, Dec 05 '16 at 17:27

score 2 · Answer 1 · answered Jun 03 '13 at 15:16

2

That's very deliberately how Multimap works. Putting an empty String and a normal String into a Multimap makes exactly no difference, and a Multimap will treat a key without any values as completely nonexistent. Please read Multimap Is Not A Map from the Guava wiki.

answered Jun 03 '13 at 15:16

Louis Wasserman

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Actaully item count is 9 but above output is 8 . Its elminate the empty values row. – user2444474 Jun 03 '13 at 16:51
mp.values()[10, 11, 12, 1, 2, 3, 14, ] 8 – user2444474 Jun 03 '13 at 16:52
but i need values if empty also – user2444474 Jun 03 '13 at 16:53
What? The number of elements in `[10, 11, 12, 1, 2, 3, 14, ]` is 8. That's the correct answer, and it includes the empty value. It's not clear what you want instead. – Louis Wasserman Jun 03 '13 at 17:37
No , I want empty value too..because key total count is 9 but value total is 8 . Look at the programe , there is one key e, total count not included the e element.As we calculated size for mp object.It should return 9. – user2444474 Jun 03 '13 at 18:16
When I run your program, I get out 9. Are you running the exact same program as you gave in the original question? – Louis Wasserman Jun 03 '13 at 18:40
Do you have any idea about to get the values as like mentioned in the question ? – user2444474 Jun 03 '13 at 19:32
I can't tell what you mean by "to get the values as like mentioned in the question." Please be more specific what you want and don't have. – Louis Wasserman Jun 03 '13 at 22:21

TreeMultimap doesn't allow null or empty values?

1 Answers1