index « HashMap « Java Collection Q&A

1. Java HashMap indexed on 2 keys    stackoverflow.com

I want to create a HashMap in java for users with preferences. This would be easy to do in a database, but unfortunately I can't use a database. What I need ...

2. Java - get index of key in HashMap?    stackoverflow.com

In java if I am looping over the keySet() of a HashMap, how do I (inside the loop), get the numerical index of that key? Basically, as I loop through the map, ...

3. What is inside an empty index of a Hashmap?    stackoverflow.com

I have a hashmap that is 101 keys in size, but I know for sure about 6 of those have no data inside, and there may be more without data as ...

4. how to implement n:m relation in java?    stackoverflow.com

Sorry for this newbie question, but I just never worked with java... My problem is I need to implement an n:m relation in java. The use case is a catalog.

• a product can be ...

5. How do I grab an index from an array in a HashMap?    stackoverflow.com

I've got a HashMap<Object, String[]> I just want to grab the 0 index position from the String[]. How do I do that? Can I just do this? mMap.get(position)[0]?

6. Only iterate over a part of a Map    stackoverflow.com

I have data stored in a HashMap, which I want to access via multiple threads simultaneously, to split the work done on the items. Normally (with a List for example) I would ...

7. Is it good practice to index a list of objects with a hashmap?    stackoverflow.com

I need to find objects by an attribute. One option is to iterate over an array of objects and check for each object that the attribute matches. The other option is to put ...

8. HashMap and finding index difference    coderanch.com

i have a program thats has a data file that contains different strings like ATGTCATGG ATGCGATGGGGGGTCGCCCC ATGTTT the out put would be for this the closest two are 3 apart in length their indices are 0,2. And the code so far that i have writen reads the file and checks how long each of the strngs are and it gives me ...

9. hashmap which has 5 storage area for every index.    forums.oracle.com

I want to store 5 seperate datas for every hashmap index... And if i write a data strorage class and save every instance to the hashmap, is it logical and fast enough? For example: HashMap.Put("mystorage1",new Store5Data(data1,data2,data3,data4,data5)) If this way is not ok how can i implement this with the ready classes or packages? Thank you

10. Using HashMap for Inverted Index    forums.oracle.com

11. Hashmap, Lists and Indexing    forums.oracle.com

Ive had this design problem come up twice already (in the last 3 weeks) so i figured its time to consult the sages. Though I know how to use a hashmap in code I dont really know anything technical about them (or any other map or hash---). I dont really have a grasp when to use them over ArrayList or LinkedList ...