More Than Equations

Just an Average Day

3 min read

🔖 Background Information

The Java Stream API gives developers the power to use functional programming techniques on problems that were usually solved with classes in Java. This has a variety of benefits including potential performance gains, the ability to parallelize code, and the ability to model your code as a series of data transformations.

🎯 Problem Statement

  1. Write a set of four functions that calculate the minimum, maximum, sum, and average of an array of integers. These functions should use a for loop like we have seen in the class many times before.
  2. Write a set of four functions that calculate the minimum, maximum, sum, and average of an array of integers. These functions should use the Java Stream API.

✅ Acceptance Criteria

  • I expect to see eight functions total.
  • Test your functions thoroughly through JUnit tests.

📋 Dev Notes

  • You are allowed to use any and all helper functions included in the Stream API.

🖥️ Example Output

You might define your eight functions like so:

public int maximumUsingForLoop(int[] nums) { ... }
public int minimumUsingForLoop(int[] nums) { ... }
public int sumUsingForLoop(int[] nums) { ... }
public int averageUsingForLoop(int[] nums) { ... }
 
public int maximumUsingStream(int[] nums) { ... }
public int minimumUsingStream(int[] nums) { ... }
public int sumUsingStream(int[] nums) { ... }
public int averageUsingStream(int[] nums) { ... }

📝 Thought Provoking Questions

  1. Which syntax do you prefer for these calculations - streams or loops? Why?
  2. What is the difference between a “mutable” and “immutable” structure in Java?
  3. What does the map function do in a stream?
  4. What does the filter function do in a stream?
  5. What does the reduce function do in a stream?

💼 Add-Ons For the Portfolio

(One Credit) Evens Only

Write a function that takes an array of integers and filters out any odd numbers. You must use the Java Stream API for this solution and test it using JUnit.

(One Credit) Odds Only

Write a function that takes an array of integers and filters out any even numbers. You must use the Java Stream API for this solution and test it using JUnit.

(One Credit) Add Five

Write a function that takes an array of integers and returns a new array of integers where all of the numbers have been incremented by five. You must use the Java Stream API for this solution and test it using JUnit.

(One Credit) Square Numbers

Write a function that takes an array of integers and returns a new array of integers where all of the numbers have been squared. You must use the Java Stream API for this solution and test it using JUnit.

📘 Works Cited

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