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Summary - Methods

Combine return, overloading and scope to write a math helper.

Summary: Methods

In this group you saw the basics of methods: static definition, returning values with return, void methods, overloading and scope.

A method does one job; when called, the flow enters it, and when done, it returns. With overloading you can reuse the same name with different parameters.

Now you will combine these to write a small calculator helper: define and use add, square and printResult methods.

Practice Calculator helper

Define two methods: static int add(int a, int b) returns the sum; static void printResult(int r) prints Result: r. From main, call printResult(add(7, 8)).

Starter code

Main.java
public class Main {
  public static void main(String[] args) {
    // Call the print method with the result of the add method
  }
  // Define static int add(int a, int b)
  // Define static void printResult(int r)
}

Sample solution

Main.java
static int add(int a, int b) { return a + b; }
static void printResult(int r) {
  System.out.println("Result: " + r);
}
// inside main:
printResult(add(7, 8));

Expected output

Result: 15

Questions and answers

Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.

1 What defines a method's signature?

  • Return type and name Correct answer
  • Only the name
  • Name and parameter types
  • Body and return type

Explanation: Signature = name + parameter types; return type is not included.

2 Fill in the blank: call the method

Question 
int sum = add(3, ____);
Answer 
int sum = add(3, 4);

Explanation: The add(3, 4) call returns the sum.

3 Match concept to explanation

Term Meaning
return Hands a value out
void Returns no value
overloading Same name, different signature
scope Block where a variable is valid

All lessons in Beginner

1 Java basics

  1. What is Java?
  2. The main method
  3. Comments
  4. Class skeleton
  5. javac and java
  6. Summary - Java basics

2 Variables

  1. int and double
  2. boolean
  3. String
  4. Naming variables
  5. final variables
  6. Summary - Variables

3 Data types

  1. Primitive types
  2. Type casting
  3. String concatenation
  4. Math class
  5. BigInteger and BigDecimal
  6. Summary - Data types

4 Project: Calculator

  1. Project design
  2. Add/subtract
  3. Multiply/divide
  4. Error handling
  5. Putting it together

5 Operators

  1. Arithmetic
  2. Comparison
  3. Logical
  4. Bitwise
  5. Assignment and increment
  6. Summary - Operators

6 String basics

  1. length and charAt
  2. equals and equalsIgnoreCase
  3. indexOf and substring
  4. toUpperCase and trim
  5. String.format
  6. Summary - String basics

7 Conditionals

  1. The if statement
  2. else and else if
  3. Nested if
  4. switch
  5. Ternary
  6. Summary - Conditionals

8 Loops

  1. The for loop
  2. The while loop
  3. do-while
  4. break and continue
  5. for-each
  6. Summary - Loops

9 Project: Shopping cart

  1. Cart design
  2. Adding items
  3. Calculating totals
  4. Updating quantity
  5. Putting it together

10 Arrays

  1. Declaring arrays
  2. Array access
  3. Filling arrays
  4. Multi-dimensional arrays
  5. Copying arrays
  6. Summary - Arrays

11 Array methods

  1. Arrays.sort
  2. Arrays.toString
  3. Arrays.binarySearch
  4. Arrays.copyOf
  5. Arrays.fill
  6. Summary - Array methods

12 Collections

  1. ArrayList
  2. add and get
  3. HashMap
  4. put and get
  5. HashSet
  6. Summary - Collections

13 Methods

  1. Defining methods
  2. return
  3. void methods
  4. Method overloading
  5. Scope
  6. Summary - Methods

14 Method parameters

  1. Primitive parameters
  2. Object parameters
  3. varargs
  4. Multiple values via array
  5. final parameters
  6. Summary - Method parameters

15 Project: To-do CLI

  1. Task model
  2. Adding tasks
  3. Listing tasks
  4. Completing tasks
  5. Putting it together

16 String builder

  1. StringBuilder
  2. append
  3. insert and delete
  4. reverse
  5. toString
  6. Summary - String builder

17 Input and output

  1. Scanner
  2. nextInt and nextLine
  3. System.out.printf
  4. BufferedReader
  5. try-with-resources
  6. Summary - Input and output

18 Enum

  1. Declaring enums
  2. values and valueOf
  3. Enum fields
  4. Enum methods
  5. switch with enum
  6. Summary - Enum

19 Exception basics

  1. try/catch
  2. finally
  3. throw
  4. Exception hierarchy
  5. Multiple catch
  6. Summary - Exception basics

20 Beginner final

  1. Project design
  2. Data model
  3. Business logic
  4. Error handling
  5. Putting it together