Java Cheatsheet: Data Types, Control Flow, Classes, Inheritance, and More

This Java cheatsheet covers some of the most commonly used features and syntax in the Java programming language, including data types, control flow statements, arrays, classes and objects, inheritance, interfaces, and exception handling. Whether you’re a beginner or an senior Java developer, this cheatsheet is a handy reference guide to help you quickly look up key concepts and code snippets.

Data Types:

Data TypeDescription
byte8-bit signed two’s complement integer
short16-bit signed two’s complement integer
int32-bit signed two’s complement integer
long64-bit signed two’s complement integer
floatSingle-precision 32-bit IEEE 754 floating point
doubleDouble-precision 64-bit IEEE 754 floating point
booleantrue or false
charSingle 16-bit Unicode character
Data Types

Control Flow Statements:

if-elseExecutes a block of code if a certain condition is true, and another block of code if the condition is false
switchEvaluates an expression and executes code block based on different cases
forExecutes a block of code a fixed number of times
whileRepeats a block of code while a certain condition is true
do-whileRepeats a block of code at least once, and continues to repeat the block as long as a certain condition is true
breakTerminates the innermost loop or switch statement
continueSkips the current iteration of a loop and continues with the next iteration
Control Flow Statements


dataType[] arrayName;Declares an array of the specified data type
arrayName = new dataType[arraySize];Creates an array of the specified data type and size
dataType[] arrayName = {value1, value2, value3, …};Creates an array and initializes it with specified values

Classes and Objects:

class className { … }Defines a class
className objectName = new className();Creates an instance of a class
objectName.methodName();Calls a method on an object
public static void main(String[] args) { … }The main method, which is the entry point of a Java program
Classes and Objects


class subclassName extends superclassName { … }Defines a subclass that inherits from a superclass
super.methodName();Calls a method from the superclass


interface interfaceName { … }Defines an interface
class className implements interfaceName { … }Implements an interface

Exception Handling:

try { … } catch (Exception e) { … } finally { … }Handles exceptions that might occur in the try block
throw new Exception();Throws an exception
throws ExceptionDeclares that a method might throw an exception
Exception Handling

I hope this helps!

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