SinWave.java

import java.lang.Math; 
import java.util.Vector; 
import java.io.ByteArrayInputStream;
import java.io.File;
import java.io.IOException;
import javax.sound.sampled.*; 

public class SinWave { 
    private static final float SAMPLE_RATE = 44100.0f;
    private static final int   SAMPLE_SIZE = 16;
    private static final int   CHANNEL     = 2;
    private static final int   FRAME_SIZE  = 2;
    private static final float FRAME_RATE  = 44100.0f;

    private static final int VOLUME = 50;

    public static void main (final String[] arg) 
        throws IOException {

        Vector<Float> freqs = new Vector<Float>();
        for (int i = 0; i < arg.length; i++) {
            freqs.add(Float.valueOf(arg[i]));
        }

        int buffsize = ((int)SAMPLE_RATE * CHANNEL);
        byte[] buff = new byte[(buffsize * freqs.size())];
        int cursor = 0;

        for (Float freq : freqs) {
            // SAMPLE_RATE 内で target_hz 個の波形を入れる必要が
            // あるため、一回の波形に割り当てるサンプル数は 
            // (SAMPLE_RATE / target_hz) になる。
            float target_freq = freq.floatValue();
            int samples_per_round = (int)(SAMPLE_RATE / target_freq);

            // target_freq 回波形を書く
            for (int i = 0; i < (int)target_freq; i++) {
                // 1回の波形を samples_per_round の点に分けて書く
                for (int x = 0; x < samples_per_round; x++) {
                    float progress = ((float)x / samples_per_round);
                    double radian  = progress * (2 * Math.PI);
                    byte y = (byte)(Math.sin(radian) * VOLUME); 
                    buff[cursor++] = y; // Left
                    buff[cursor++] = y; // Right
                }
            }
        }

        // WAVE ファイルとして出力
        AudioFormat fmt = new AudioFormat( 
            // AudioFormat.Encoding encoding
            AudioFormat.Encoding.PCM_SIGNED, 
            SAMPLE_RATE, // sampleRate 
            SAMPLE_SIZE, // sampleSizeInBits 
            CHANNEL,     // channels 
            FRAME_SIZE,  // frameSize 
            FRAME_RATE,  // frameRate 
            true         //int bigEndian 
        );
        AudioInputStream audio_stream = new AudioInputStream(
            new ByteArrayInputStream(buff), fmt, cursor);
        File outfile = new File("sinwave.wav");
        AudioSystem.write(audio_stream
            , AudioFileFormat.Type.WAVE, outfile);
    }
}