Tag Archives: collections

Cheat Sheet for Selecting Map/List/Set in Java

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I have prepared a cheat sheet that can help to select appropriate Map, Set or List implementation when required. Java API has many implementations of interfaces mentioned, and it is not always clear which implementation should be used in a particular scenario. The cheat sheet comes in the form of a flow chart, which makes it easy to follow and understand.

The idea was inspired by Sergiy Kovalchuk. Sergiy made a flow chart using the most commonly used collections. I tried to take it one step further and make it much more thorough.  Please do let me know if anything needs to be corrected. I hope this can help developers out there to choose the right collection for the right job.

Cheat sheet for selecting appropriate set/list/map in Java

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Inspired by Sergiy Kovalchuk

Brainteaser: ArrayList VS TreeSet

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When I came across the following example I did not expect the results that the program has printed :) hehe…

Question: What does this program print? Why?

import java.util.*;

public class SetList {

    public static void main(String[] args) {

    Set<Integer> set =
    			new TreeSet<Integer>();
    List<Integer> list =
    			new ArrayList<Integer>();

    for (int i = -3; i < 3; i++) {
        set.add(i);
        list.add(i);
    }

    for (int i = 0; i < 3; i++) {
        set.remove(i);
        list.remove(i);
    }

     System.out.println(set + " " + list);
   }
}

Looking forward for your answers dear readers

Resources:
Effective Java