Glossary

A list of exact instructions the computer follows in order.

A tool that turns your Java code into bytecode the JVM can run.

javac Main.java

Java Virtual Machine — the runtime engine that loads and executes Java bytecode.

Java Development Kit — development tools plus the runtime components needed to build and run Java applications.

Java Runtime Environment — the traditional name for a runtime-only bundle. Modern setups commonly use a JDK or an application-specific runtime instead of a separate JRE download.

The in-between code (.class file) produced by the compiler and run by the JVM.

The grammar rules of Java — semicolons, braces, spelling of keywords.

A named box in memory that holds a value.

int age = 19;

What kind of value a variable can hold: int, double, char, boolean, String.

A symbol that does something to values, like + - * / %.

A question with a true/false answer that decides which code runs.

if (marks >= 40)

Code that repeats while a condition stays true.

for (int i = 0; i < 5; i++)

A fixed-size list of values of the same type, numbered from 0.

int[] marks = {80, 75, 90};

A named block of code you can call again and again.

int add(int a, int b)

A blueprint that describes what an object knows (fields) and can do (methods).

A real thing built from a class, living in memory.

Student s = new Student();

A variable that belongs to an object, describing its data.

A special class member, with the class name and no return type, that initializes a new object.

A keyword meaning 'the current object'. Used when a parameter and field share a name.

Keeping data private and exposing safe public methods to use it.

Public methods that read or change a private field in a controlled way.

A child class reusing the fields and methods of a parent class.

class Dog extends Animal

A keyword to reach the parent class's constructor or method.

A child class giving its own version of a parent method (same signature).

Several methods with the same name but different parameter lists.

One name, many behaviours — the right method is chosen for the actual object.

Showing only what something does, hiding how it does it.

A partly finished class that cannot be turned into an object by itself.

A contract of method names a class promises to implement.

class Report implements Printable

A problem that happens while the program runs, like dividing by zero.

Code that attempts a risky action and handles the failure instead of crashing.

A cleanup block that normally runs after try and catch, whether or not an exception occurred.

Belongs to the class itself, shared by all objects, not copied per object.

Cannot be changed: a constant value, a method that can't be overridden, or a class that can't be extended.

A namespace that groups related Java types; its name usually matches the source folder structure.

package college.students;