camera - Manual focus in camera2, android

Question

i am looking for an example of manual focus in camera2 in android. I tried to get minimum focus distance and available focal lengths shown below, but it didn't help. How to control the focus distance ?

float minimumLens = characteristics.get(CameraCharacteristics.LENS_INFO_MINIMUM_FOCUS_DISTANCE);

float[] lensDistances = characteristics.get(CameraCharacteristics.LENS_INFO_AVAILABLE_FOCAL_LENGTHS); 

I need to control it with seekbar. Thanks in advance.

Answer 1

 switch (seekBar.getId()) {
            case R.id.sb_focus:
                float minimumLens = mCameraCharacteristics.get(CameraCharacteristics.LENS_INFO_MINIMUM_FOCUS_DISTANCE);
                float num = (((float) i) * minimumLens / 100);
                mPreviewBuilder.set(CaptureRequest.LENS_FOCUS_DISTANCE, num);
                int showNum = (int) num;
                mSeekBarTextView.setText("focus：" + showNum);
                break;}

be careful ,CONTROL_AF_MODE should be OFF.
https://github.com/pinguo-yuyidong/Camera2/blob/master/app/src/main/java/us/yydcdut/androidltest/ui/DisplayFragment.java
code in Line 1109