Я пишу класс Guitar37, в котором 37 клавиш отображаются на шкалу цветности c от 110 Гц до 880 Гц.
public static final String KEYBOARD =
"q2we4r5ty7u8i9op-[=zxdcfvgbnjmk,.;/' "; // keyboard layout
Учитывая эту строку, i-й символ строки соответствует частоте 440 * 2 (i - 24) / 12 . Пример: символ «q» - 110 Гц, «i» - 220 Гц, «v» - 440 Гц и «» (клавиша пробела) - 880 Гц.
public class Guitar37 implements Guitar {
public static final String KEYBOARD =
"q2we4r5ty7u8i9op-[=zxdcfvgbnjmk,.;/' "; // keyboard layout
private GuitarString[] strings;
private int currentTime;
public Guitar37() {
currentTime = 0;
strings = new GuitarString[37];
for (int i = 0; i < 37; i++) {
strings[i] = new GuitarString(440 * Math.pow(2, (i - 24) / 12));
}
}
public void playNote(int pitch) {
strings[pitch + 24].pluck();
}
public boolean hasString(char key) {
return KEYBOARD.indexOf(key) != -1;
}
public void pluck(char key) {
if(!hasString(key)) {
throw new IllegalArgumentException();
}
strings[KEYBOARD.indexOf(key)].pluck();
}
public double sample() {
double sum = 0.0;
for (int i = 0; i < 37; i++) {
sum += strings[i].sample();
}
return sum;
}
public void tic() {
for (int i = 0; i < 37; i++) {
strings[i].tic();
}
currentTime++;
}
public int time() {
return currentTime;
}
}
Это текущая версия моего класса Guitar37. Когда я пытаюсь проверить это, ожидаемый результат должен возвращать все 37 частот:
[110, 116, 123, 130, 138, 146, 155, 164, 174, 184, 195, 207, 220, 233, 246, 261, 277, 293, 311, 329, 349, 369, 391, 415, 440, 466, 493, 523, 554, 587, 622, 659, 698, 739, 783, 830, 880]
Вместо этого мой класс возвращает только четыре частоты
[110, 220, 440, 880]
Класс GuitarString:
// This class is used for debugging the Guitar37 class. It is not an example
// to be emulated. When a string is plucked, it is set to the integer part of
// the string's frequency plus 0.25. It goes down by 10 each time tic is
// called until it becomes less than or equal to 10 when it is set to 0.
import java.util.*;
public class GuitarString {
static Set<Integer> nums = new TreeSet<>(); // observed frequency values
double value;
double freq;
public GuitarString(double frequency) {
freq = frequency;
nums.add((int) frequency);
}
public void pluck() {
value = (int) freq + 0.25;
}
public void tic() {
if (value <= 10) {
value = 0.0;
} else {
value = value - 10;
}
}
public double sample() {
return value;
}
}
класс test37 (класс, используемый для проверки класса Guitar37):
// This is a program that can be used to test the basic functionality of the
// Guitar37 class. It does not test all of the functionality.
//
// The main method has an array of 37 frequency values that should be produced
// by a correctly working Guitar37 class. The actual frequencies don't all end
// in 0.25, but this version of GuitarString converts them to that form so that
// it is easier to understand the output produced by the program. In
// particular, it is easier to see if it is properly adding new values as notes
// are played.
import java.util.*;
public class Test37 {
public static final String KEYBOARD =
"q2we4r5ty7u8i9op-[=zxdcfvgbnjmk,.;/' "; // keyboard layout
public static void main(String[] args) {
double[] frequencies =
{110.25, 116.25, 123.25, 130.25, 138.25, 146.25, 155.25, 164.25,
174.25, 184.25, 195.25, 207.25, 220.25, 233.25, 246.25, 261.25,
277.25, 293.25, 311.25, 329.25, 349.25, 369.25, 391.25, 415.25,
440.25, 466.25, 493.25, 523.25, 554.25, 587.25, 622.25, 659.25,
698.25, 739.25, 783.25, 830.25, 880.25};
Guitar g = new Guitar37();
compare(frequencies, GuitarString.nums);
for (int i = 0; i < KEYBOARD.length(); i++) {
int note = i - 24;
System.out.println("Playing note " + note + " (initially " +
frequencies[i] + ")");
g.playNote(note);
advance(g, 4);
char key = KEYBOARD.charAt(i);
System.out.println("Plucking string '" + key + "'");
if (g.hasString(key)) {
g.pluck(key);
advance(g, 4);
} else {
System.out.println("ERROR: not recognizing key '" + key + "'");
}
System.out.println("making an extra call on tic");
// throw in an extra call on tic without calling time and sample
g.tic();
System.out.println();
}
// now test a few unsupported values of pitch which should be ignored
// but should not throw an exception
int[] unsupportedPitch = {-32, -25, 13, 18};
for (int n : unsupportedPitch) {
System.out.println("testing playNote for unsupported pitch " + n);
g.playNote(n);
advance(g, 4);
System.out.println();
}
}
// This method advances the simulation the given number of tics reporting
// the time reading and sample values from the given guitar.
public static void advance(Guitar g, int tics) {
for (int i = 0; i < tics; i++) {
System.out.println("time " + g.time() + " sample = " + g.sample());
g.tic();
}
}
// This method compares the array nums with the set of numbers in nums2,
// suspending program execution if the two sets of numbers differ.
public static void compare(double[] nums, Set<Integer> nums1) {
Set<Integer> nums2 = new TreeSet<>();
for (double n : nums) {
nums2.add((int) n);
}
if (!nums1.equals(nums2)) {
System.out.println("Wrong frequencies for Guitar37 construction.");
System.out.println("should be approximately: " + nums2);
System.out.println("yours are approximately: " + nums1);
System.exit(1);
}
}
}