Java Programming Fundamentals
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Questions and Answers

Which statement accurately describes the use of the static keyword when applied to a method in Java?

  • The method belongs to the class itself rather than to any specific instance of the class. (correct)
  • The method can only be called once during the program's execution.
  • The method cannot be accessed from outside the class.
  • The method can be overridden by subclasses.

Consider the following code snippet: System.out.println(5 + 3 * 2);. What will be the output?

  • 16
  • 10
  • 13
  • 11 (correct)

In Java, a constructor can have a return type, such as int or String.

False (B)

Which access modifier restricts access of a class member to only within its own class?

<p>private (D)</p> Signup and view all the answers

The ______ keyword is used to create a new object in Java.

<p>new</p> Signup and view all the answers

What is the primary purpose of the return keyword in a Java method?

<p>To return a value and/or control back to the calling method.</p> Signup and view all the answers

Which of the following is NOT a primitive data type in Java??

<p>String (D)</p> Signup and view all the answers

Match each term with its corresponding description regarding Object-Oriented Programming principles:

<p>Encapsulation = Bundling data and methods that operate on that data within a class, and restricting direct access to some of the object's components. Inheritance = A mechanism where a new class acquires the properties and behaviors of an existing class. Polymorphism = The ability of an object to take on many forms. This often occurs when a parent class reference is used to refer to a child class object.</p> Signup and view all the answers

Which of the following is a valid way to declare an array in Java?

<p>Both A and B (C)</p> Signup and view all the answers

What is the result of the following expression: true && false?

<p>false (C)</p> Signup and view all the answers

Which of the following loop types is specifically designed to execute a set number of times?

<p>for loop (C)</p> Signup and view all the answers

Which statement accurately describes a method signature in Java?

<p>Method name and parameter list (B)</p> Signup and view all the answers

The main() method can be overloaded in Java.

<p>True (A)</p> Signup and view all the answers

String objects in Java are mutable.

<p>False (B)</p> Signup and view all the answers

Explain the difference between StringBuilder and StringBuffer.

<p><code>StringBuilder</code> is not synchronized and is faster for single-threaded operations, while <code>StringBuffer</code> is synchronized and thread-safe.</p> Signup and view all the answers

What are accessor and mutator methods? Provide an example.

<p>Accessor methods (getters) retrieve the value of a field, while mutator methods (setters) modify the value of a field. Example: <code>public int getAge() { return age; }</code> and <code>public void setAge(int age) { this.age = age; }</code>.</p> Signup and view all the answers

The ______ keyword refers to the current object instance and is used to distinguish between instance variables and parameters when they have the same name.

<p>this</p> Signup and view all the answers

Match the loop type with its appropriate use case:

<p>for loop = Iterating a known number of times while loop = Iterating until a specific condition is false do-while loop = Iterating at least once, then until a condition is false</p> Signup and view all the answers

Flashcards

System.out.println()

The correct way to display text output in Java.

Object-Oriented Programming

A fundamental style of programming based on objects, including encapsulation, inheritance, and polymorphism.

void keyword

Used in a method declaration to specify that the method does not return any value.

x++ (post-increment)

A post-increment operator increases the value of a variable by one after returning its original value.

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private access modifier

Restricts access to the declaring class itself.

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new keyword

Allocates memory for a new object of a class.

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Valid Identifier

A valid sequence of characters used to name a variable, method, class, or other element. Must start with a letter, underscore (_), or dollar sign ($).

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static keyword

Belongs to the class itself, not to any instance of the class.

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Valid Array Declaration in Java?

Both int[] arr; and int arr[]; are valid array declarations in Java.

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true && false

true && false evaluates to false because both conditions must be true for the entire expression to be true.

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Loop for Specific Iterations

A for loop executes a specific number of times, controlled by initialization, condition, and increment/decrement.

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Method Signature

A method signature includes the method name and its parameter list (types and order).

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Multiple Constructors

A class can have multiple constructors with different parameter lists (method overloading).

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Break Statement

The break statement exits a loop prematurely, skipping any remaining iterations.

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Final Keyword

The final keyword prevents a variable from being reassigned after its initial assignment.

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Accessor vs. Mutator Methods

Accessor methods (getters) retrieve the value of a field, while mutator methods (setters) modify the value of a field.

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StringBuilder vs. StringBuffer

StringBuilder is not synchronized (faster, single-threaded), while StringBuffer is synchronized (thread-safe).

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Primitive vs. Reference Types

Primitive types hold values directly; reference types hold references (pointers) to objects in memory.

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Study Notes

Multiple Choice Questions

  • The correct syntax to print "Hello, World" in Java is System.out.println(“Hello, World”);
  • Compilation is NOT a principle of Object-Oriented Programming
  • The keyword void defines a method that does not return a value
  • The code int x = 10; System.out.println(x++); outputs 10
  • The private access modifier allows a class member to be accessible only within its own class
  • The new keyword in Java creates an object
  • firstVariable is a valid identifier in Java.
  • System.out.println(5 + 3 * 2); will output 11.
  • Constructors must have the same name as the class and can be private.
  • The static keyword indicates the method belongs to the class rather than an instance.
  • String is NOT a primitive data type in Java
  • The default value of an integer variable in Java is 0.
  • The Scanner class is used to handle user input in Java.
  • The code String str = "Hello"; str = str + " World"; System.out.println(str); outputs "Hello World".
  • The if-else structure can have multiple else if branches.
  • The return keyword returns control to the calling method and a value from the method.
  • int[] arr; and int arr[]; are valid ways to declare an array in Java.
  • The expression true && false results in false.
  • A for loop is used to create a loop that executes a specific number of times.
  • A method signature is correctly described by its method name and parameter list.

True/False Questions

  • The main() method can be overloaded in Java: True
  • A class can have multiple constructors: True
  • The assert statement can be used to test assumptions in code: True
  • String objects in Java are mutable: False
  • The break statement can be used to exit a loop prematurely: True
  • The final keyword can prevent a variable from being reassigned: True
  • The switch statement can only evaluate integer expressions: False
  • The Math.random() method returns a random integer: False
  • The StringBuffer class is synchronized and thread-safe: True
  • A method can have multiple return statements: True

Short Answer Questions

  • A while loop continues until a specified condition is false, while a for loop iterates a set number of times, based on initialization, condition, and increment/decrement expressions.
  • Accessor (getters) methods retrieve the value of a field, while mutator (setters) methods modify the value of a field.
    • Example:
      • Getter: public int getAge() { return age; }
      • Setter: public void setAge(int age) { this.age = age; }
  • The assert operator is used for debugging to make sure a condition is true at a certain point in the program.
  • StringBuilder is not synchronized and is faster for single-threaded operations, while StringBuffer is synchronized and thread-safe.
  • Example Java class:
class Car {
  private String model;
  private int year;

  public Car(String model, int year) {
    this.model = model;
    this.year = year;
  }

  public String getModel() {
    return model;
  }
}
  • The Scanner class gets input from sources like user console input, and can parse primitive types and strings.
  • Method overloading allows multiple methods with the same name but different parameters (types, number, or both) to exist in the same class.
    • Example:
    public int add(int a, int b) { return a + b; }
public double add(double a, double b) { return a + b; }
  • The this keyword refers to the current object instance and distinguishes between instance variables and parameters having the same name.
  • The software engineering life cycle phases: Requirements Analysis, Design, Implementation, Testing, Deployment, and Maintenance.
  • Primitive types are basic data types (like int, char, boolean) holding values directly, while reference types (like String, Arrays, Objects) hold references to the actual data in memory.

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Description

Test your knowledge of introductory Java programming concepts. This quiz covers syntax, object-oriented principles, data types, and basic operations. Review access modifiers, constructors, and user input handling in Java.

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