D286 Java Fundamentals - Set 1 - Part 2

Correct Answer: == compares references, while equals() compares character content

For objects, == tests whether two references point to the same object. String.equals() compares actual character content, which is almost always what is intended.

Correct Answer: Returns true only if both operands are true, with short-circuit evaluation

The && operator returns true only when both operands are true and short-circuits, skipping evaluation of the right operand when the left is already false.

Correct Answer: Skipping evaluation of the second operand when the result is already determined

Short-circuit evaluation stops as soon as the outcome is known, which both improves efficiency and allows safe patterns such as checking for null before dereferencing.

Correct Answer: Executing different code paths based on a boolean condition

An if-else statement chooses between alternative blocks of code based on whether a boolean condition evaluates to true or false.

Correct Answer: do-while

A do-while loop evaluates its condition after executing the body, so the body always runs at least one time.

Correct Answer: Iterating over arrays and collections without an explicit index

The enhanced for loop iterates directly over each element of an array or Iterable collection, removing index management and reducing off-by-one errors.

Correct Answer: int[] numbers = new int[10];

The syntax int[] numbers = new int[10]; declares an array reference and allocates space for 10 int elements, each initialized to 0.

Correct Answer: n - 1

Java arrays use zero-based indexing, so valid indices run from 0 to length minus one. Accessing index n throws ArrayIndexOutOfBoundsException.

Correct Answer: length

Arrays expose a public final field named length. Collections such as ArrayList use the size() method instead.

Correct Answer: ArrayIndexOutOfBoundsException

Accessing an index that is negative or greater than or equal to the array length throws ArrayIndexOutOfBoundsException at runtime.

Correct Answer: The method name together with its parameter types

A method signature consists of the method name and its parameter list types. The return type is not part of the signature for overloading purposes.

Correct Answer: Defining multiple methods with the same name but different parameter lists

Overloading defines several methods sharing a name but differing in parameter number or types. The compiler selects the correct one based on the arguments supplied.

Correct Answer: No, the parameter list must differ

Return type is not part of the method signature for overload resolution, so methods differing only by return type cause a compile-time error.

Correct Answer: A blueprint defining the state and behavior of objects

A class defines fields (state) and methods (behavior) that its instances will have, serving as a template from which objects are created.

Correct Answer: An instance of a class created at runtime

An object is a concrete instance of a class, occupying memory and holding its own field values while sharing the class's method definitions.

Correct Answer: new

The new keyword allocates memory for a new object, invokes the appropriate constructor, and returns a reference to the created instance.

Correct Answer: A special method that initializes a newly created object

A constructor has the same name as its class, has no return type, and runs when an object is created to initialize its state.

Correct Answer: The compiler provides a no-argument default constructor

When no constructor is declared, the compiler supplies a default no-argument constructor. Declaring any constructor removes this automatic default.

Correct Answer: The current object instance

The this reference points to the current object, commonly used to distinguish fields from parameters with the same name or to invoke another constructor.

Correct Answer: Restricting direct access to fields and exposing controlled methods

Encapsulation hides internal state behind private fields and exposes controlled access through methods, protecting invariants and allowing implementation to change safely.