I need to insert a key and an element, containing the key and another value (which will be selected in the end from the map sorted by keys) into an HashMap. I decided to lastly convert the HashMap to a TreeMap to sort it, but the HashMap gets filled with data that change at every insert: here is the code
Tag: hashmap
Hashmap – returning key and setting it as value of an object
I have two CSV files, one “crimeUSA.csv” with the headers state, city, population etc. and one StatesAbbreviations with the headers states, abbrev . First I read the “crimeUSA.csv” file and create CityCrime objects. Instead of using the state in this file, I want to match it with the s…
HashMap: Is there a way to search by hashcode and not by key?
I may sound completely wrong but: I’ve read as many posts as I could find here about HashMap and hashcode . I did not get what I was looking for exactly. I am going to try to be as precise as I can. Let’s say I have a huge hashmap where : keys are of type my_struct and values as
Returning they key with lowest value in a nested hashmap
I have this hashmap: {count : {req : deadline}, count : {req : deadline}, count : {req : deadline}, count : {req : deadline}} If I put it in values is: {0 : {req : 5}, 1 : {req : 3}, 2 : {req : 1}, 3 : {req : 3}} I want to compare all the deadline values and
Updating value of particular keys in MultiKeyMap in Java
I was trying to update the values of set of particular keys in MultiKeyMap in Java but not able to get how to do that. Suppose I want to update (key1, key2, value1) same set of key with different value (key1, key2, value2). If I simply perform put in MultiKeyMap then it create new row and doesn’t update…
Using HashMap dynamically for parameter mapping in mybatis
Okay so this is kinda re-posting of this question Inserting HashMap Values to a table using ibatis (but I am looking for a different way – the answer wont work for me).. DB1GetStudentDataMapper.xml (this queries to one database) DB2InsertStudentMapper.xml (this queries to different database) DB2InsertSt…
Hasmap merge function value inside an object
I am trying to get a quantity count of products from a list of sales. So what I have is: The current way I have done it is based on this answer of integers: how to merge more than one hashmaps also sum the values of same key in java So, right now im traversing a list of sale objects,
Converting POJO into map
I have a Java class having 10 attributes, I want to convert this into 3 maps(Breaking it into 5,3,2 fields resepectively). I did some research and found that Jackson’s ObjectMapper can be used by doing something like this: This will be creating a single map for all the attributes in my POJO. What I want…
How to get file name having particular content in it using java?
Here I am trying to read a folder containing .sql files and I am getting those files in an array, now my requirement is to read every file and find particular word like as join if join is present in the file return filename or else discard , someone can pls help me with this .. Answer You can search
How can UserDefined class be a key of hashmap if hashCode() & equals() return same value
I am trying to implement HashMap with UserDefined class as Key, i am successfull even when I implement both hashCode() (returns 0 for every object) & equals() (returns false for every object). My Code output:- Can anyone let me know the reason how it’s working Answer This is happening because equals…