100+ Free Oracle Java Foundations Practice Questions

Java Basics, What Is Java, and Basic Java Elements

Describe Java's key features and platforms, distinguish the JDK, JRE, and JVM, explain bytecode and garbage collection, identify the parts of a basic program including the main method, and compile with javac and run with the java launcher.

Working with Java Data Types and the String Class

Declare and initialize variables, use final for constants, work with the eight primitive types and their defaults, perform widening and narrowing casts, declare Strings, and call String methods such as length, equals, compareTo, and Integer.parseInt.

Working with Java Operators and Decision Statements

Apply arithmetic, increment and decrement, relational, compound assignment, and conditional operators, respect operator precedence, and build decisions with if-then-else, switch, and the ternary operator.

Working with Java Arrays and ArrayLists

Declare and create one-dimensional and two-dimensional arrays, access elements and the length field, handle out-of-bounds errors, create and manipulate an ArrayList with add and get, and compare arrays with ArrayLists.

Using Looping Statements

Write for, enhanced for, while, and do-while loops, nest loops, trace iteration counts, and direct flow using break and continue while choosing the right loop for the task.

Working with Methods

Declare methods with parameters and return types, understand void and pass-by-value, overload methods, call static methods, and reason about local variable scope and code reuse.

Object-Oriented Programming, Classes, and Constructors

Create classes and objects with new, write constructors and rely on the default constructor, apply encapsulation with private fields and getters and setters, use this and inheritance with extends, and distinguish instance from static members.

Debugging, Documentation, and Exception Handling

Tell syntax errors from logic errors, read a stack trace, write Javadoc comments and tags such as @param and @return, handle common exceptions with try-catch-finally, and use the Math and Random utility classes.