private void demo3() {

    //restore default setting, you can omit all following setting and goto the final refresh() show
    simpleWaveform.init();

    LinkedList<Integer> ampList = new LinkedList<>();
    //generate random data
    for (int i = 0; i < 80; i++) {
        ampList.add(randomInt(-50, 50));
    }
    simpleWaveform.setDataList(ampList);//input data to show

    //define bar gap
    simpleWaveform.barGap = 30;

    //define x-axis direction
    simpleWaveform.modeDirection = SimpleWaveform.MODE_DIRECTION_LEFT_RIGHT;

    //define if draw opposite pole when show bars
    simpleWaveform.modeAmp = SimpleWaveform.MODE_AMP_ABSOLUTE;
    //define if the unit is px or percent of the view's height
    simpleWaveform.modeHeight = SimpleWaveform.MODE_HEIGHT_PERCENT;
    //define where is the x-axis in y-axis
    simpleWaveform.modeZero = SimpleWaveform.MODE_ZERO_CENTER;
    //if show bars?
    simpleWaveform.showBar = true;

    //define how to show peaks outline
    simpleWaveform.modePeak = SimpleWaveform.MODE_PEAK_PARALLEL;
    //if show peaks outline?
    simpleWaveform.showPeak = true;

    //show x-axis
    simpleWaveform.showXAxis = true;
    xAxisPencil.setStrokeWidth(1);
    xAxisPencil.setColor(0x88ffffff);//the first 0x88 is transparency, the next 0xffffff is color
    simpleWaveform.xAxisPencil = xAxisPencil;

    //define pencil to draw bar
    barPencilFirst.setStrokeWidth(15);
    barPencilFirst.setColor(0xff1dcf0f);
    simpleWaveform.barPencilFirst = barPencilFirst;
    barPencilSecond.setStrokeWidth(15);
    barPencilSecond.setColor(0xff1dcfcf);
    simpleWaveform.barPencilSecond = barPencilSecond;

    //define pencil to draw peaks outline
    peakPencilFirst.setStrokeWidth(5);
    peakPencilFirst.setColor(0xfffe2f3f);
    simpleWaveform.peakPencilFirst = peakPencilFirst;
    peakPencilSecond.setStrokeWidth(5);
    peakPencilSecond.setColor(0xfffeef3f);
    simpleWaveform.peakPencilSecond = peakPencilSecond;

    //the first part will be draw by PencilFirst
    simpleWaveform.firstPartNum = 20;//first 20 bars will be draw by first pencil

    //define how to clear screen
    simpleWaveform.clearScreenListener = new SimpleWaveform.ClearScreenListener() {
        @Override
        public void clearScreen(Canvas canvas) {
            canvas.drawColor(Color.TRANSPARENT, PorterDuff.Mode.CLEAR);
        }
    };
    // set touch listener
    simpleWaveform.progressTouch = new SimpleWaveform.ProgressTouch() {
        @Override
        public void progressTouch(int progress, MotionEvent event) {
            Log.d("", "you touch at: " + progress);
            simpleWaveform.firstPartNum = progress;//set touch position back to its progress
            simpleWaveform.refresh();
        }
    };
    //show...
    simpleWaveform.refresh();

    demo_introduce.setText("demo3: amplitude bar");
}

<maxproj.com.simplewaveform.SimpleWaveform
    android:id="@+id/simplewaveform"
    android:layout_width="match_parent"
    android:layout_height="300dp"
    android:layout_margin="10dp" />