Handy Functions cheat cheet

Replace character in string

String result = yourString.replaceAll("&", "&amp;");

Convert the string to a char array

char[] charArray = originalString.toCharArray();

Get character a index n

char c = str.charAt(n)

Get a substring from a string

Creating a hastable

Hashtable<String, Integer> hashtable = new Hashtable<>()

Adding values to a hastable

hashtable.put("One", 1);

Retrieving values from hastable

int value = hashtable.get("Two");

Removing a key-value pair

hashtable.remove("Three");

Checking if a key is inside hastable

hashtable.containsKey(keyToCheck)

Creating a list

List<String> myList = List.of("A", "B", "C", "D", "E", "F", "G");

Creating a sublist from index i to n (n not included)

List<String> subList = myList.subList(i, n);

Get value at index n

myList.get(n)

Create a set

import java.util.HashSet; 
import java.util.Set;

Set<String> stringSet = new HashSet<>();

Add to a set

stringSet.add("Apple");

Check if set contains an element

stringSet.contains("Banana");

Remove element from set

stringSet.remove("Orange");