Methods in Programming

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Questions and Answers

What is a characteristic of a non-void method?

  • It does not return any value.
  • It returns a value specified in the method header. (correct)
  • It must print results to display output.
  • It cannot be called from other methods.

Which of the following methods is an example of a void method?

  • public static int max(int num1, int num2)
  • public static double calculateArea()
  • public static void main(String[] args) (correct)
  • public static String howdy()

What would be the output if the method 'max(5, 2)' is called?

  • 5 (correct)
  • 5 and 2
  • Error: Arguments must be non-negative.
  • 2

What type of method is used to perform an operation without needing to return a value?

<p>System.out.println() (D)</p> Signup and view all the answers

Which statement correctly describes the method 'public static String howdy()'?

<p>It returns a string value 'Hello!'. (A)</p> Signup and view all the answers

What is the main difference between void methods and non-void methods?

<p>Void methods do not return any value, whereas non-void methods do. (A)</p> Signup and view all the answers

Which method can be directly used to obtain user input?

<p>JOptionPane.showInputDialog() (C)</p> Signup and view all the answers

What does the method call 'str.indexOf()' do?

<p>It returns the first occurrence of a character in str. (A)</p> Signup and view all the answers

How does the stack store elements when calling methods?

<p>Last-in, first-out (LIFO). (D)</p> Signup and view all the answers

What is the primary difference between arguments and parameters?

<p>Arguments are values that fill parameters in the method call; parameters are part of the method header. (B)</p> Signup and view all the answers

What is the correct order for passing parameters when calling a method?

<p>Arguments must be passed in the same order and type as parameters. (B)</p> Signup and view all the answers

What happens to the stack when a method call is finished?

<p>The calling method retains its stack space while the called method is released. (B)</p> Signup and view all the answers

Which statement about method overloading is true?

<p>Methods can be overloaded based on different parameter types. (B)</p> Signup and view all the answers

What is the notable difference between pass-by-value and pass-by-reference when calling methods?

<p>Pass-by-value creates a copy of a variable's value, whereas pass-by-reference creates a copy of its address. (C)</p> Signup and view all the answers

What must be true for a method call with parameters?

<p>It must have parameters matching the types of passed arguments. (A)</p> Signup and view all the answers

What is the main concept described when multiple methods have the same name but different parameter lists?

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

In the context of method overloading, which of the following parameter differences is NOT valid?

<p>Different variable names (B)</p> Signup and view all the answers

What will happen when the following overloaded method is called: max(5, 2) in the context of the provided example?

<p>It will compile and print 5 (D)</p> Signup and view all the answers

What defines the scope of a local variable?

<p>From declaration to the end of the block containing the method (B)</p> Signup and view all the answers

Which type of variable can be referenced from any method in the program?

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

Which of the following statements about local variables is true?

<p>Local variables exist only within the method they are declared in. (C)</p> Signup and view all the answers

In the provided max method examples, what output will result from calling max(5.5, 2.2)?

<p>It will print 5.5 (C)</p> Signup and view all the answers

What happens if two methods are declared with the same name and parameter types?

<p>It causes a compile-time error. (C)</p> Signup and view all the answers

What is the primary purpose of overloading methods in a class?

<p>To handle different data types or numbers of arguments (A)</p> Signup and view all the answers

How does the sequence of parameter types affect method overloading?

<p>It differentiates methods by the order in which parameters are declared. (B)</p> Signup and view all the answers

Flashcards

What is a method?

A collection of statements grouped together to perform an operation. Methods can be reusable blocks of code.

What is a void method?

A method that does not return a value. Used to perform actions like printing or displaying output.

What is a non-void method?

A method that returns a value of the same type declared in its header. Used to perform calculations or calculations with output.

What does indexOf() do?

The indexOf() method returns the index (position) of the first occurrence of a specified character within a string.

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What does length() do?

The length() method returns the number of characters in a string.

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What does System.out.println() do?

The System.out.println() method prints a line of text to the console.

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What does JOptionPane.showInputDialog() do?

The JOptionPane.showInputDialog() method displays a dialog box that allows the user to input text.

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What does Math.random() do?

The Math.random() method generates a random number between 0.0 (inclusive) and 1.0 (exclusive).

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Method Overloading

The ability to define multiple methods with the same name within the same class as long as their parameters differ in number, type, or order of types.

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Variable Scope

The part of a program where a variable can be referenced and used.

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Local Variable

A variable declared within a method; its scope is limited to the method it's declared in.

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Global Variable

Variables declared outside of any methods, usually at the top of the program, and accessible from anywhere within the class.

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Void Method

A method that doesn't return a value; It performs an action, like printing output.

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Non-Void Method

A method that returns a value of the same type declared in its header.

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Method call

The process of executing a method. It involves providing arguments as specified in the method's header.

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Stack

A temporary storage area used to store data when methods are called. Data is stored in a 'last-in, first-out' order.

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Arguments

Values passed to a method when it's called. These values correspond to the parameters defined in the method header.

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Parameters

Variables declared in a method's header that receive values from the arguments passed during a method call.

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Pass-by-value

The process of copying the value of an argument to a parameter. This means any changes made to the parameter within the method don't affect the original argument.

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Study Notes

Methods

  • A method is a collection of statements grouped to perform an operation.
  • Methods can be predefined (e.g., Math.random(), str.length(), System.out.println()) or custom-written.
  • Custom methods can be categorized as:
    • Void: Does not return a value. Often used to display output.
    • Non-void: Returns a value of a specified type.

Example Method Types

  • Void examples: Methods that don't return any value, often used to print results to the console.

  • Non-void examples: Methods that return a value of a specific type, often used to calculate and return results. Example: Determining maximum value.

Calling Methods

  • To use a method, invoke or call it by its name, providing input values (arguments) as needed.

  • Method calls occur within the context of your program's main method (or other appropriate method).

  • When a method is called, parameters (arguments) are stored in memory on the stack.

  • After a method completes execution, control returns to the calling method, and memory allocated to the called method is released.

Passing Parameters (Arguments)

  • Parameters or arguments passed to a method are copied for use within the method (pass-by-value).
  • The original variables outside the method are not affected by operations within the method.

Overloading Methods

  • You can have multiple methods with the same name in a class, as long as the parameter lists are different.
  • The different parameter lists distinguish the methods, even with similar names.
  • This allows for flexibility to have varied functions under the same method name.

Variable Scope

  • Variables declared inside a method (local variables) have a scope limited to that method.
  • Variables declared outside any method (global variables) are accessible throughout the program, within every method.

Static vs. Non-static Methods

  • Static methods belong to the class itself and can be called without creating an object of the class.
  • Non-static methods belong to an object of the class and require an object to be created beforehand to be called.

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