ทำแอพ ถ่ายภาพแบบหลาย ๆ ภาพแล้วแสดงพร้อมกันแต่ติดปัญหา Error ผู้รู้ช่วยแนะนำด้วยครับ

ทำแอพถ่ายภาพครับ แต่ติดปัญหา error เวลาที่จะถ่ายภาพแล้วให้แสดงในหน้านี้ 2 ภาพ
คือ  ถ่ายภาพครั้งที่  1 แสดงใน ImageView1
      ถ่ายภาพครั้งที่ 2 แสดงใน ImageView2
รบกวนช่วยแนะนำ หน่อยครับ
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ตัวนี้เป็น code ครับ
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[open_code]public static final int REQUEST_CAMERA = 2;

ImageView imageView;
ImageView imageView2;
Uri uri;
Uri uri2;

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    imageView = (ImageView)findViewById(R.id.imageView);

    Button btnIntent = (Button)findViewById(R.id.btnIntent);
    btnIntent.setOnClickListener(new OnClickListener() {
        public void onClick(View v) {
            Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
            String timeStamp =
                    new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
            String imageFileName = "IMG_" + timeStamp + ".jpg";
            File f = new File(Environment.getExternalStorageDirectory()
                    , "DCIM/Camera/" + imageFileName);
            uri = Uri.fromFile(f);
            intent.putExtra(MediaStore.EXTRA_OUTPUT, uri);
            startActivityForResult(Intent.createChooser(intent
                    , "Take a picture with"), REQUEST_CAMERA);
        }
    });

    imageView2 = (ImageView)findViewById(R.id.imageView2);

    Button btnIntent2 = (Button)findViewById(R.id.btnIntent2);
    btnIntent2.setOnClickListener(new OnClickListener() {
        @Override
        public void onClick(View v) {
            Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
            String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
            String imageFileName = "IMG_"+ timeStamp +".jpg";
            File f = new File(Environment.getExternalStorageDirectory(),"DCIM/Camera/" + imageFileName);
            uri2 = Uri.fromFile(f);
            intent.putExtra(MediaStore.EXTRA_OUTPUT,uri2);
            startActivityForResult(Intent.createChooser(intent,"Tak a picture with"),REQUEST_CAMERA);
        }
    });


}

public void onActivityResult(int requestCode, int resultCode, Intent data) {
    if (requestCode == REQUEST_CAMERA && resultCode == RESULT_OK) {
        getContentResolver().notifyChange(uri, null);
        ContentResolver cr = getContentResolver();
        try {
            Bitmap bitmap = Media.getBitmap(cr, uri);

            imageView.setImageBitmap(bitmap);
            Toast.makeText(getApplicationContext()
                    , uri.getPath(), Toast.LENGTH_SHORT).show();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }if (requestCode == REQUEST_CAMERA && resultCode == RESULT_OK){
        getContentResolver().notifyChange(uri2,null);
        ContentResolver aa = getContentResolver();
        try{
            Bitmap bitmap = Media.getBitmap(aa,uri2);
            imageView2.setImageBitmap(bitmap);
            Toast.makeText(getApplicationContext(),uri2.getPath(),Toast.LENGTH_SHORT).show();
        }catch (Exception e){
            e.printStackTrace();
        }
    }
}
[/close_code]
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ส่วนตัวนี้เป็น Logcat
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[open_code]java.lang.RuntimeException: Failure delivering result ResultInfo{who=null, request=2, result=-1, data=null} to activity {com.example.teerapon.takephoto/com.example.teerapon.takephoto.MainActivity}:     java.lang.NullPointerException
        at android.app.ActivityThread.deliverResults(ActivityThread.java:3351)
        at android.app.ActivityThread.handleSendResult(ActivityThread.java:3394)
        at android.app.ActivityThread.access$1300(ActivityThread.java:135)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1244)
        at android.os.Handler.dispatchMessage(Handler.java:102)
        at android.os.Looper.loop(Looper.java:136)
        at android.app.ActivityThread.main(ActivityThread.java:5001)
        at java.lang.reflect.Method.invokeNative(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:515)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
        at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
        at android.os.Parcel.readException(Parcel.java:1471)
        at android.os.Parcel.readException(Parcel.java:1419)
        at android.content.IContentService$Stub$Proxy.notifyChange(IContentService.java:486)
        at android.content.ContentResolver.notifyChange(ContentResolver.java:1621)
        at android.content.ContentResolver.notifyChange(ContentResolver.java:1610)
        at android.content.ContentResolver.notifyChange(ContentResolver.java:1590)
        at com.example.teerapon.takephoto.MainActivity.onActivityResult(MainActivity.java:85)
        at android.app.Activity.dispatchActivityResult(Activity.java:5423)
        at android.app.ActivityThread.deliverResults(ActivityThread.java:3347)
        at android.app.ActivityThread.handleSendResult(ActivityThread.java:3394)
        at android.app.ActivityThread.access$1300(ActivityThread.java:135)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1244)
        at android.os.Handler.dispatchMessage(Handler.java:102)
        at android.os.Looper.loop(Looper.java:136)
        at android.app.ActivityThread.main(ActivityThread.java:5001)
        at java.lang.reflect.Method.invokeNative(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:515)
[/close_code]
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รบกวนด้วยนะครับ