All About Java Syntax

Concept

Description

Syntax Example

Variables

Storing data values.

int number = 5;

Data Types

Types of data (e.g., int, double, char, String).

int myNum = 5;
double rate = 3.14;
String name = "Java";

Operators

Performing operations on variables and values.

int sum = a + b; // Arithmetic
boolean isTrue = (a == b); // Logical

Control Structures

Directing the flow of the program.

if (condition) {
    // code
} else {
    // code
}
for (int i = 0; i < 5; i++) {
    // code
}

Arrays

Storing multiple values in a single variable.

int[] myArray = new int[5];

Methods

Blocks of code designed to perform tasks.

public int multiply(int a, int b) {
    return a * b;
}

Classes and Objects

Templates for objects and creating instances.

public class MyClass {
    // fields, methods, constructors
}
MyClass myObj = new MyClass();

Inheritance

Deriving new classes from existing ones.

class MyChildClass extends MyParentClass {
    // additional fields, methods
}

Interfaces

Implementing methods across different classes.

interface MyInterface {
    // abstract methods
}
class MyClass implements MyInterface {
    // implementation of abstract methods
}

Exception Handling

Managing errors and exceptions in code.

try {
    // code that may throw an exception
} catch (Exception e) {
    // code to handle the exception
}

Generics

Enabling classes and methods to operate on types.

class MyGenericClass<T> {
    // using the type parameter T
}

Abstract Classes

Classes that cannot be instantiated.

abstract class MyAbstractClass {
    // abstract methods
}

Polymorphism

Allowing methods to perform differently based on the object.

@Override
public void display() {
    // overridden method
}

Encapsulation

Restricting direct access to some of an object's components.

private int data;

Static Keyword

Denoting class-level properties and behaviours.

static int value = 5;
public static void myStaticMethod() {
    // static method code
}

Final Keyword

Creating constants and preventing inheritance.

final int MAX = 100;
final class MyFinalClass {
    // class code
}

Concurrency

Handling multiple processes or threads.

Runnable runnable = () -> {
    // thread task
};
Thread myThread = new Thread(runnable);
myThread.start();

Java API & Libraries

Utilizing Java's built-in libraries and functions.

List<String> list = new ArrayList<>();
list.add("Hello");

Term

Definition

Class

A blueprint for creating objects containing methods, variables, and more.

Object

An instance of a class; it has state and behavior as defined by its class.

Method

A block of code within a class that performs a specific task.

Variable

A container for storing data values.

Constructor

A special method used to initialize new objects of a class.

Inheritance

The mechanism by which one class can inherit the features of another class.

Interface

An abstract type used to specify a behavior that classes must implement.

Abstract Class

A class that cannot be instantiated and is often used as a base class.

Polymorphism

The ability of a variable, function, or object to take on multiple forms.

Encapsulation

The bundling of data and methods that operate on the data within one unit, like a class.

Package

A namespace for organizing classes and interfaces in a logical manner.

Array

A container object that holds a fixed number of values of a single type.

Exception

An event that disrupts the normal flow of the program's instructions.

Loop

A control structure that repeatedly executes a block of code as long as a particular condition is true.

Conditional Statement

A statement that performs different actions based on the truth value of a condition.

Data Type

A classification of data that tells the compiler or interpreter how the programmer intends to use the data.

Static

A keyword that indicates a field or method is shared among all instances of a class.

Final

A keyword used to declare constants or methods that cannot be overridden, or classes that cannot be subclassed.

Enum

A special data type that enables for a variable to be a set of predefined constants.

Annotation

A form of metadata that provides data about a program but is not part of the program itself.

Thread

A thread of execution in a program, allowing for concurrent operations within the program.

Garbage Collection

The process by which Java programs perform automatic memory management.

JVM (Java Virtual Machine)

An abstract machine that enables a computer to run a Java program.

JDK (Java Development Kit)

A software development kit for developing Java applications.

JRE (Java Runtime Environment)

Provides the libraries, the Java Virtual Machine, and other components to run applications written in Java.