Java

setup install java:

 sudo apt install default-jdk

datatypes:

boolean Boolean

int Integer

float Float

double Double

char Character

byte

short

long

Non-Primitive (Reference) Data Types:

String has .length() and is not itterable in for each loop?

Array has .length

{% hint style="info" icon="question" %} arrays can be null? {% endhint %}

class

interface

object

public class Solution{

}

Keyword:

var for type inference (added in java 10 )

Collections:

import java.util.ArrayList;
import java.util.ArrayDeque;
import java.util.HashSet;
import java.util.HashMap;

Map:

getOrDefault(key,default)

get(key)

push(key,value)

equals(map2)