# artemkorsakov's solution

## to Resistor Color in the Java Track

Published at Feb 15 2019 · 2 comments
Instructions
Test suite
Solution

Resistors have color coded bands, where each color maps to a number. The first 2 bands of a resistor have a simple encoding scheme: each color maps to a single number.

These colors are encoded as follows:

• Black: 0
• Brown: 1
• Red: 2
• Orange: 3
• Yellow: 4
• Green: 5
• Blue: 6
• Violet: 7
• Grey: 8
• White: 9

Mnemonics map the colors to the numbers, that, when stored as an array, happen to map to their index in the array: Better Be Right Or Your Great Big Values Go Wrong.

More information on the color encoding of resistors can be found in the Electronic color code Wikipedia article

# Running the tests

You can run all the tests for an exercise by entering

``````\$ gradle test
``````

## Source

Maud de Vries, Erik Schierboom https://github.com/exercism/problem-specifications/issues/1458

## Submitting Incomplete Solutions

It's possible to submit an incomplete solution so you can see how others have completed the exercise.

### ResistorColorTest.java

``````import org.junit.Before;
import org.junit.Test;
import org.junit.Ignore;

import static org.junit.Assert.assertEquals;

public class ResistorColorTest {

private ResistorColor resistorColor;

@Before
public void setup() {
resistorColor = new ResistorColor();
}

@Test
public void testBlackColorCode() {
String input = "black";
int expected = 0;

assertEquals(expected, resistorColor.colorCode(input));
}

@Ignore("Remove to run test")
@Test
public void testWhiteColorCode() {
String input = "white";
int expected = 9;

assertEquals(expected, resistorColor.colorCode(input));
}

@Ignore("Remove to run test")
@Test
public void testOrangeColorCode() {
String input = "orange";
int expected = 3;

assertEquals(expected, resistorColor.colorCode(input));
}

@Ignore("Remove to run test")
@Test
public void testColors() {
String[] expected = {"black", "brown", "red", "orange", "yellow", "green", "blue", "violet", "grey", "white"};

assertEquals(expected, resistorColor.colors());
}

}``````
``````import java.util.Arrays;

class ResistorColor {
int colorCode(String color) {
return Colors.valueOf(color).ordinal();
}

Object[] colors() {
return Arrays.stream(Colors.values()).map(Enum::name).toArray(String[]::new);
}

private enum Colors {
black, brown, red, orange, yellow, green, blue, violet, grey, white
}
}``````

Hi! Enums has an in-build ordinal value which holds their position as an int. You could therefore skip `num` and use `ordinal()` instead.

Also, instead of collecting the stream to a list and then converting it to an array, you can use `Stream.toArray()` instead.

Solution Author
commented 244 days ago

Hi, uzilan! Thank you for your comment - now I know a little more. I will apply this in my work.

### What can you learn from this solution?

A huge amount can be learned from reading other people’s code. This is why we wanted to give exercism users the option of making their solutions public.

Here are some questions to help you reflect on this solution and learn the most from it.

• What compromises have been made?