OOP Thursday

/*
write a java program that stores names of 3
students (alice, bob, james) in an array and
display them
    - use list
    - use Set
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create an array list polymorphically

Before java 5
List names = new ArrayList(); // no specific data type

// Using Generics
List<Integer> names = new ArrayList<Integer>();

/* Wrapper classes : allows you to use primitive types as objects
    - int = Integer
    - float = Float
    - String = String
-----------------------------------------------------------------

Difference between sets and lists
    - sets do not preserve the order of elements
        - no duplicates
    - lists is the opposite of sets

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Maps store elements as pairs (key => value), unique pairs
e.g: Create a map to store countries and their capitals

rwanda => kigali
kenya => nairobi

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ORM : object relational mapping
    technology that allows you to map classes to database tables

public class BankAccount {}                 java
create table bank_account();                sql

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MINECOFIN / IFMIS
    - Business Analyst : analysis, design
    - Developer : java, coding

    - System Admins : linux
        - System Administration
        - Bash Programming, task automation
        - Network Administration

    - Database Admins : postgresql, oracle
        - performance tuning (index, partitioning, replica)

    - Support Team

*/

import java.util.Set;
import java.util.HashSet;
import java.util.ArrayList;
import java.util.List;
import java.util.Collections;
import java.util.Map;
import java.util.HashMap;

public class MyClass {
    public static void main(String ... args) {
        String[] names1 = new String[3];
        List<String> names2 = new ArrayList<>();
        Set<String> names3 = new HashSet<>();
        Map<String, String> countries = new HashMap<>(); // jdk 8

        names1[0] = "alice";
        names1[1] = "bob";
        names1[2] = "james";

        names2.add("alice");
        names2.add("bob");
        names2.add("james");

        names3.add("alice");
        names3.add("bob");
        names3.add("james");

        countries.put("rwanda", "kigali"); // entries
        countries.put("kenya", "nairobi");
        countries.put("congo", "kinshasa");

        Collections.sort(names2);

        for (String name: names) {
            System.out.println(name);
        }

        System.out.println(countries.get("rwanda"));

        Set<String> keys = countries.keySet();
        System.out.println(keys);

        System.out.println("Country\tCapital");

        for (String key : keys) {
            System.out.println(key);
        }
    }
}