// ######### CHEATSHEET ALERT! ########
// Your cheatsheet content is here for Java!
Java Basics
Syntax:
Classes: public class ClassName { ... }
Methods: public static void methodName() { ... }
Main Method: public static void main(String[] args) { ... }
Variables:
Declaration: int x;
Initialization: int x = 5;
Final Variables: final int MAX = 100;
Data Types:
Primitive: boolean, char, byte, short, int, long, float, double
Reference: String, arrays, objects
Control Flow
Conditionals:
if (condition) { ... } else if (condition) { ... } else { ... }
switch (expression) { case value: ... break; }
Loops:
for (init; condition; update) { ... }
while (condition) { ... }
do { ... } while (condition);
Arrays:
Declaration: int[] arr = new int[5];
Initialization: int[] arr = {1, 2, 3};
Accessing Elements: arr[0]
Strings:
String str = "Hello";
Concatenation: str " World"
Length: str.length()
Substring: str.substring(1, 4)
Object-Oriented Programming (OOP)
Classes and Objects:
Constructor: public ClassName() { ... }
Instance Variables: private int id;
Methods: public void method() { ... }
Inheritance:
class ChildClass extends ParentClass { ... }
Interfaces:
interface InterfaceName { void method(); }
Implementation: class ClassName implements InterfaceName { ... }
Polymorphism:
Method Overloading: Same method name with different parameters.
Method Overriding: Subclass method with the same name as superclass.
Exception Handling :
try { ... } catch (Exception e) { ... } finally { ... }
Throwing Exceptions: throw new Exception("Message");
Collections
List:
ArrayList<String> list = new ArrayList<>();
Methods: add(), remove(), get(), size()
Map:
HashMap<String, Integer> map = new HashMap<>();
Methods: put(), get(), remove(), containsKey()
Set:
HashSet<String> set = new HashSet<>();
Methods: add(), remove(), contains()
You are totally free to add-up anything in case I have missed something.
Note : This cheatsheet covers core Java concepts but remember, Java has many more features, libraries, and frameworks like Spring, Hibernate, etc., which would require their own detailed summaries.