How can I convert a String into a HashMap? into Where the keys are first_name, last_name and gender and the values are naresh, kumar, male. Note: Keys can be any thing like city = hyderabad. I am looking for a generic approach. Answer This is one solution. If you want to make it more generic, you can use the …
Tag: hashmap
Can an array be used as a HashMap key?
If a HashMap’s key is a String[] array: Can you access the map by using a newly created String[] array, or does it have to be the same String[] object? Answer It will have to be the same object. A HashMap compares keys using equals() and two arrays in Java are equal only if they are the same object. If
HashMap value auto increment
when I was coding, one question occurred to me, which is if the value part(Integer) in the HashMap is able to auto-increment in the following scenario? Answer Consider using an AtomicInteger: Also consider using a for loop to simplify the code.
Does HashMap.clear() resize inner hash table to the original size?
What happens to the HashMap after this code execution? HashMap m = new HashMap(); for (int i = 0; i < 1024 * 1024; i++) m.put(i, i); m.clear(); After 1M puts the inner hash table will grow …
How to create a HashMap with two keys (Key-Pair, Value)?
I have a 2D array of Integers. I want them to be put into a HashMap. But I want to access the elements from the HashMap based on Array Index. Something like: For A[2][5], map.get(2,5) which returns a value associated with that key. But how do I create a hashMap with a pair of keys? Or in general, multiple key…
How to print all key and values from HashMap in Android?
I am trying to use HashMap in Android sample project. Now, am doing sample project for learn android. I just store keys and values in HashMap, i want to show the keys and their values in EditView. I followed below code in my sample project. But, first key and value only printing in EditView. In EditView iOS =…
How to calculate HashMap memory usage in Java?
I was asked in an interview to calculate the memory usage for HashMap and how much estimated memory it will consume if you have 2 million items in it. For example: The mapping is like this. How would I estimate the memory usage of this HashMap Object in Java? Answer The short answer To find out how large an o…
Shortcut for adding to List in a HashMap
I often have a need to take a list of objects and group them into a Map based on a value contained in the object. Eg. take a list of Users and group by Country. My code for this usually looks like: However I can’t help thinking that this is awkward and some guru has a better approach. The closest
C# Java HashMap equivalent
Coming from a Java world into a C# one is there a HashMap equivalent? If not what would you recommend? Answer Dictionary is probably the closest. System.Collections.Generic.Dictionary implements the System.Collections.Generic.IDictionary interface (which is similar to Java’s Map interface). Some notable…