Collections

General idea without bloat of additional coding methods

Structures of Data

Ways to store information in an ordered manner so the data can be called upon when needed. The values can be referenced by index or iterated over where additional processing could be performed.

Common Sequences

Arrays

int[] wholeNumbers = new int[5]; // [item, item, item, item, item]            
String[] words = new String[5];  // [item, item, item, item, item]

Lists

import java.util.List;
import java.util.ArrayList;

List<String> listOfideas = new ArrayList<>();
listOfideas.add("serendipity");
listOfideas.add("synchronicity");
listOfideas.add("determinism");
System.out.println(listOfideas);

List<Integer> listOfWholeNumbers = new ArrayList<>(); 
listOfWholeNumbers.add(5);
listOfWholeNumbers.add(15);
listOfWholeNumbers.add(51);
System.out.println(listOfWholeNumbers);

Documentation

List Interface
ArrayList Class

Associative Arrays

Using key:value pairs. Values can be accessed by calling the key of the associated value. Versus where you could need to loop over the entire collection to find the desired value.

import java.util.Map;
import java.util.HashMap;

Map<String, Boolean> animals = new HashMap<String, Boolean>();

animals.put("dog", true);
animals.put("libera", false);
animals.put("girazelle", false);
animals.put("cat", true);

System.out.println(animals);