Tone.java

Below is the syntax highlighted version of Tone.java from §1.5 Input and Output.

/******************************************************************************
 *  Compilation:  javac-introcs Tone.java
 *  Execution:    java-introcs Tone hz seconds
 *  Dependencies: StdAudio.java
 *
 *  This program takes the frequency and duration from the command line,
 *  and plays a sine wave of the given frequency for the given duration.
 *
 *  % java-introcs Tone 440.0 1.5
 *
 ******************************************************************************/

public class Tone {
    public static void main(String[] args) {
        double hz       = Double.parseDouble(args[0]);    // frequency in Hz
        double duration = Double.parseDouble(args[1]);    // duration in seconds

        int n = (int) (StdAudio.SAMPLE_RATE * duration);

        // build sine wave with desired frequency
        double[] a = new double[n+1];
        for (int i = 0; i <= n; i++) {
            a[i] = Math.sin(2 * Math.PI * i * hz / StdAudio.SAMPLE_RATE);
        }

        // play using standard audio
        StdAudio.play(a);
    }
}