Oracle Certified Professional: Java SE 21 Developer

Exam number 1Z0-830. The full exam syllabus we prepare students against, once they've finished the core Java course.

⏱ Duration: 30–40 days

Module 01

Handling date, time, text, numeric and boolean values

Use primitives and wrapper classes
Evaluate arithmetic and boolean expressions using the Math API, precedence rules, type conversions and casting
Manipulate text using String and StringBuilder, including text blocks
Work with date, time, duration, period, instant and time-zone objects, including daylight saving time

Module 02

Controlling program flow

Use control constructs: if/else, switch statements and expressions, loops, break and continue

Module 03

Using object-oriented concepts

Declare and instantiate objects, including nested classes; understand object life-cycle and garbage collection
Create classes and records; define instance/static fields and methods, constructors, initializers
Implement method overloading, including var-args
Understand variable scope, apply encapsulation, create immutable objects, use local variable type inference
Implement inheritance, including abstract/sealed/record types; override methods including from Object
Implement polymorphism; use casting, instanceof and pattern matching
Create and use interfaces, identify functional interfaces, use private/static/default interface methods
Create and use enums with fields, methods and constructors

Module 04

Handling exceptions

Handle exceptions using try/catch/finally, try-with-resources and multi-catch blocks, including custom exceptions

Module 05

Working with arrays and collections

Create arrays and collections: List, Set, Map, Deque
Add, remove, update, retrieve and sort collection elements

Module 06

Working with streams and lambda expressions

Use object and primitive streams and lambda expressions with functional interfaces to filter, transform, process and sort data
Perform decomposition, concatenation, reduction, grouping and partitioning on sequential and parallel streams

Module 07

Packaging and deploying Java code

Define modules and expose content, declare module dependencies
Define services, providers and consumers
Compile Java code, create modular/non-modular JARs and runtime images

Module 08

Managing concurrent code execution

Create platform and virtual threads using Runnable and Callable
Manage thread lifecycle with executor services and the concurrent API
Write thread-safe code using locking and concurrent collections
Process collections concurrently and use parallel streams

Module 09

Using the Java I/O API

Read and write console and file data using I/O streams
Serialize and deserialize Java objects
Use java.nio.file to work with Path objects and file properties

Module 10

Implementing localization

Implement localization using locales and resource bundles
Parse and format messages, dates, times, numbers, currencies and percentages

A few assumptions the exam makes

Assume necessary package/import statements exist unless stated otherwise. Assume all classes are either in one file or in the same directory. Ignore unintended line breaks — treat them as part of the same line if it helps the code compile. Assume that any descriptive comment implies correctly working code.

Also expected: basics of the Java Logging API; annotations including @Override, @FunctionalInterface, @Deprecated, @SuppressWarnings and @SafeVarargs; and generics, including wildcards.