Question

Play musical chords (JAVA PROGRAMMING)

Notes and frequencies

Every musical note has a name and a frequency. You are given a file where each line contains a note name, a tab character, and a frequence, which is a floating point value. For example, here are the first few lines from the file notes_frequencies.txt:

A0      27.5
A#0     29.1353
B0      30.8677
C1      32.7032
C#1     34.6479
D1      36.7081
D#1     38.8909
E1      41.2035
F1      43.6536

Playing chords

Write a program named PlayChords that first reads the data in the notes/frequencies file into a symbol table with the note name as the key and the frequency as the value.

The program then reads from a second file called chords.txt where each line contains one or more notes names separated by whitespace. Play the specified chords one by one by gathering the notes on each line into an array and then call the method specified below to play the resulting chord.

Here's the method that should be placed into your program.

        public static void playChordOneSecond(double... frequencies) {
                final int sliceCount = (int) (StdAudio.SAMPLE_RATE * 1.0);
                final double[] slices = new double[sliceCount+1];
                for (double frequency: frequencies) {
                        for (int i = 0; i <= sliceCount; i++) {
                                slices[i] += Math.sin(2 * Math.PI * i * frequency / StdAudio.SAMPLE_RATE);
                        }
                }
                StdAudio.play(slices);
        }

Helpful information

Place the data files into the data folder in Eclipse. Copy and paste the above method into your PlayChords class.

To process a text file where each line contains a fixed set of data fields:

1. Use the method readLine in the StdIn class, which returns a string;
2. Split the string into an array of strings using the instance method split in the String class. Each of those strings in the array is a note name.
3. Declare a double array of the same length as the note array. Fill that double array by looking up for each note its corresponding frequency in the symbol table.

Answer 1

Please import std audio libraries first.

Then,

import java.io.File;

import java.io.FileNotFoundException;

import java.util.Scaner;

public class PlayChordsromFile {

public static void main(String [] args) {

File file = new File("risingchords.txt");

try {

Scanner sc = new Scanner(file);

while (sc.hasNextLine()) {

String line = sc.nextLine();

String temp[]=new double[temp.length];

for(int i=0;i<temp.length,i++){

array[i]=Double.parseDouble(temp[i]);

}

playChord(array);

}

sc.close();

}

catch (FileNotFoundException e) {

e.printStackTrace();

}

}

public static void playChord(double... frequencies) {

double duration = 0.5;

final int sliceCount = (int) (StdAudio.SAMPLE_RATE * duration);

final double[] slices = new double[sliceCount+1];

for (int i = 0; i<= sliceCount, i++) {

for (double frequency: frequencies) {

slices[i] += Math.sin(2 * Math.PI * i * frequency / StdAudio.SAMPLE_RATE);

}

slices[i] /= fequencies.length;

}

StdAudio.play(slices);

}

}