1. Strings in Java

• Strings in Java are not a primitive data type
• Java has a class named String
• All Strings that we implement are instances of said class
• Strings are immutable, their values remain constant after they’re created

1.1 String Pool

The String pool is a special memory region, located in the Heap, where Strings are allocated. The reason that the String Pool exists is to try to optimize memory. For example if we create the following strings

String s1 = "Luis"
String s2 = "Luis"

The JVM will optimize memory by storing only one copy of the value Luis, so s1 and s2 can reference the same value.

1.2 Different ways of initializing a String

There is something courious about strings, and that is peculiar. And that is that you can initialize them in 2 different ways.

String s1 = "Luis";
String s2 = new String("Luis");

1.3 Comparing Strings

There is a difference if you compare Strings using == or the .equals operator. And we can appreciate that in this example.

String s1 = "Luis";
String s2 = new String("Luis");

if(s1 != s2) System.out.println("True, because == will comparate memory reference instead of actual values");
if(s1.equals(s2)) System.out.println("True, because .equals is comparing actual values instead of memory reference");

2. Array vs ArrayList in Java

| | Array | ArrayList | Details | |—————–|——————————————————————————————————————————————|————————————————————————————————————————————————————–|———————————————————————————————————————————————————–| | Declaration | int[] arr = new int[10]; | ArrayList arrList = new ArrayList(); | - Arrays need to be initialized with a fixed size
- ArrayList have dynamic size | | Origin | It comes from basic Java functionality | It comes with the Collections Java Framework | - To use ArrayLists you need to import a class
- ArrayLists have methods to access and modify its members
- Arrays members are accessed trough `[]` | | Type of members | Can contain both primitive datatypes and objects
(only one datatype at the same time) | ArrayLists only supports object entries | - If you use `arrList.add(1)` It will convert it to an Integer object. | | Storage | If the datatype of the array is primitive, they're stored at a contiguous location.

If not, the storage is similar as ArrayLists. | Members of ArrayLists are always references to objects at different memory locations.

Therefore the objects are never stores in contiguous locations. | - ArrayLists have many methods like `indexOf` and `remove` which are not supported by Arrays |

3. How do HashMaps/HashTables add a new element

4. Scrum

Ceremonies -> The events present in the Scrum methodology

1. Sprint planning: The first meeting at the beginning of a Sprint, useful to discuss goals and what’s expected to be achieved in this Sprint.
2. Daily Scrum/Daily Standup: Daily meeting to get everyone on the samepage and discuss blockers.
3. Sprint Review: Informal meeting to show the demo of what was accomplished during the sprint.
4. Sprint Retrospective: In this meeting there are 2 main things to disccuss, what was done right and what needs improvement. Is important to remeber that it should feel like a safespace and not a place to blame.

Scrum Roles

1. Product Owner: Bring the product vision to life. They are in constant communication with the client.
2. Scrum Master: An expert on Scrum inside the team. Coaches devs and POs on the scrum process.
3. Team: Designers and devs that complete the storires in the backlog.

Artifacts

1. Product Backlog: The master to-do list which contains all the user-stories, fixes, features, etc.
2. Sprint backlog: It’s a chunk of the Product Backlog, which contains what’s expected to achieve during this Sprint.
3. Increment: Usable end product from a Sprint.