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to D&D Character in the Java Track

Published at May 20 2020 · 0 comments
Instructions
Test suite
Solution

For a game of Dungeons & Dragons, each player starts by generating a character they can play with. This character has, among other things, six abilities; strength, dexterity, constitution, intelligence, wisdom and charisma. These six abilities have scores that are determined randomly. You do this by rolling four 6-sided dice and record the sum of the largest three dice. You do this six times, once for each ability.

Your character's initial hitpoints are 10 + your character's constitution modifier. You find your character's constitution modifier by subtracting 10 from your character's constitution, divide by 2 and round down.

Write a random character generator that follows the rules above.

For example, the six throws of four dice may look like:

  • 5, 3, 1, 6: You discard the 1 and sum 5 + 3 + 6 = 14, which you assign to strength.
  • 3, 2, 5, 3: You discard the 2 and sum 3 + 5 + 3 = 11, which you assign to dexterity.
  • 1, 1, 1, 1: You discard the 1 and sum 1 + 1 + 1 = 3, which you assign to constitution.
  • 2, 1, 6, 6: You discard the 1 and sum 2 + 6 + 6 = 14, which you assign to intelligence.
  • 3, 5, 3, 4: You discard the 3 and sum 5 + 3 + 4 = 12, which you assign to wisdom.
  • 6, 6, 6, 6: You discard the 6 and sum 6 + 6 + 6 = 18, which you assign to charisma.

Because constitution is 3, the constitution modifier is -4 and the hitpoints are 6.

Notes

Most programming languages feature (pseudo-)random generators, but few programming languages are designed to roll dice. One such language is Troll.

Setup

Go through the setup instructions for Java to install the necessary dependencies:

https://exercism.io/tracks/java/installation

Running the tests

You can run all the tests for an exercise by entering the following in your terminal:

$ gradle test

In the test suites all tests but the first have been skipped.

Once you get a test passing, you can enable the next one by removing the @Ignore("Remove to run test") annotation.

Source

Simon Shine, Erik Schierboom https://github.com/exercism/problem-specifications/issues/616#issuecomment-437358945

Submitting Incomplete Solutions

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

DnDCharacterTest.java

import org.junit.Ignore;
import org.junit.Test;

import static org.junit.Assert.*;

public class DnDCharacterTest {

    private DnDCharacter dndCharacter = new DnDCharacter();

    @Test
    public void testAbilityModifierForScore3IsNegative4() {
        assertEquals(-4, dndCharacter.modifier(3));
    }

    @Ignore("Remove to run test")
    @Test
    public void testAbilityModifierForScore4IsNegative3() {
        assertEquals(-3, dndCharacter.modifier(4));
    }

    @Ignore("Remove to run test")
    @Test
    public void testAbilityModifierForScore5IsNegative3() {
        assertEquals(-3, dndCharacter.modifier(5));
    }

    @Ignore("Remove to run test")
    @Test
    public void testAbilityModifierForScore6IsNegative2() {
        assertEquals(-2, dndCharacter.modifier(6));
    }

    @Ignore("Remove to run test")
    @Test
    public void testAbilityModifierForScore7IsNegative2() {
        assertEquals(-2, dndCharacter.modifier(7));
    }

    @Ignore("Remove to run test")
    @Test
    public void testAbilityModifierForScore8IsNegative1() {
        assertEquals(-1, dndCharacter.modifier(8));
    }

    @Ignore("Remove to run test")
    @Test
    public void testAbilityModifierForScore9IsNegative1() {
        assertEquals(-1, dndCharacter.modifier(9));
    }

    @Ignore("Remove to run test")
    @Test
    public void testAbilityModifierForScore10Is0() {
        assertEquals(0, dndCharacter.modifier(10));
    }

    @Ignore("Remove to run test")
    @Test
    public void testAbilityModifierForScore11Is0() {
        assertEquals(0, dndCharacter.modifier(11));
    }

    @Ignore("Remove to run test")
    @Test
    public void testAbilityModifierForScore12Is1() {
        assertEquals(1, dndCharacter.modifier(12));
    }

    @Ignore("Remove to run test")
    @Test
    public void testAbilityModifierForScore13Is1() {
        assertEquals(1, dndCharacter.modifier(13));
    }

    @Ignore("Remove to run test")
    @Test
    public void testAbilityModifierForScore14Is2() {
        assertEquals(2, dndCharacter.modifier(14));
    }

    @Ignore("Remove to run test")
    @Test
    public void testAbilityModifierForScore15Is2() {
        assertEquals(2, dndCharacter.modifier(15));
    }

    @Ignore("Remove to run test")
    @Test
    public void testAbilityModifierForScore16Is3() {
        assertEquals(3, dndCharacter.modifier(16));
    }

    @Ignore("Remove to run test")
    @Test
    public void testAbilityModifierForScore17Is3() {
        assertEquals(3, dndCharacter.modifier(17));
    }

    @Ignore("Remove to run test")
    @Test
    public void testAbilityModifierForScore18Is4() {
        assertEquals(4, dndCharacter.modifier(18));
    }

    @Ignore("Remove to run test")
    @Test
    public void testRandomAbilityIsWithinRange() {
        int score = dndCharacter.ability();
        assertTrue(score > 2 && score < 19);
    }

    @Ignore("Remove to run test")
    @Test
    public void testRandomCharacterIsValid() {
        for (int i = 0; i < 1000; i++) {
            DnDCharacter character = new DnDCharacter();
            assertTrue(character.getStrength() > 2 && character.getStrength() < 19);
            assertTrue(character.getDexterity() > 2 && character.getDexterity() < 19);
            assertTrue(character.getConstitution() > 2 && character.getConstitution() < 19);
            assertTrue(character.getIntelligence() > 2 && character.getIntelligence() < 19);
            assertTrue(character.getWisdom() > 2 && character.getWisdom() < 19);
            assertTrue(character.getCharisma() > 2 && character.getCharisma() < 19);
            assertEquals(character.getHitpoints(),
                    10 + character.modifier(character.getConstitution()));
        }
    }

    @Ignore("Remove to run test")
    @Test
    public void testEachAbilityIsOnlyCalculatedOnce() {
        assertEquals(dndCharacter.getStrength(), dndCharacter.getStrength());
    }

}
import java.util.Arrays;

class DnDCharacter {

	public static int generateAbility() {
		int[] rolls = { roll(), roll(), roll(), roll() };
		Arrays.sort(rolls);
		int[] topThreeRolls = Arrays.copyOf(rolls, 3);
		return Arrays.stream(topThreeRolls).sum();
	}

    public static int calculateModifier(int constitution) {
		return (int) Math.floor((constitution - 10) / 2.0);
    }

	/**
	 *
	 * @return a random number between 1 and 6 inclusive.
	 */
	private static int roll() {
		return (int) Math.floor(Math.random() * 6) + 1;
	}

	private final int strength;
	private final int dexterity;
	private final int constituion;
	private final int intelligence;
	private final int wisdom;
	private final int charisma;
	private final int hitpoints;

	public DnDCharacter() {
		this.strength = generateAbility();
		this.dexterity = generateAbility();
		this.constituion = generateAbility();
		this.intelligence = generateAbility();
		this.wisdom = generateAbility();
		this.charisma = generateAbility();
		this.hitpoints = 10 + this.modifier(this.constituion);
	}

	/**
	 * This method is strictly exported because unit tests for this class expect an instance method.
	 * Please use the static method `generateAbility` instead of this method.
	 */
    int ability() {
		return generateAbility();
    }

	/**
	 * This method is strictly exported because unit tests for this class expect an instance method.
	 * Please use the static method `calculateModifier` instead of this method.
	 */
    int modifier(int constitution) {
		return calculateModifier(constitution);
    }

    int getStrength() {
		return this.strength;
    }

    int getDexterity() {
		return this.dexterity;
    }

    int getConstitution() {
		return this.constituion;
    }

    int getIntelligence() {
		return this.intelligence;
    }

    int getWisdom() {
		return this.wisdom;
    }

    int getCharisma() {
		return this.charisma;
    }

    int getHitpoints() {
		return this.hitpoints;
	}

}

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