java - 如何在android中的另一个类中使用方法的返回值

Question

我对 Java 和 Android 编程还是个新手，所以我对某些编程方法有点困惑。我只想问，如何在另一个类中使用方法 match_eye() 的返回值？。我只想在另一个类 (FdActivity) 中使用 mmres.minVal 和 mmres.maxVal 值，并在我的 Activity 类中显示这些值。谁能告诉我执行此操作的代码:) 谢谢

 class FdView extends SampleCvViewBase {

   public void setMinFaceSize(float faceSize)
   {
        .........
   }

   ........
   ........

   double  match_eye(Rect area, Mat mTemplate,int type){
      Point matchLoc; 
      Mat mROI = mGray.submat(area);
      int result_cols =  mGray.cols() - mTemplate.cols() + 1;
      int result_rows = mGray.rows() - mTemplate.rows() + 1;

      //Check for bad template size
      if(mTemplate.cols()==0 ||mTemplate.rows()==0){
          return 0.0;
      }
      mResult = new Mat(result_cols,result_rows, CvType.CV_32FC1);

      switch (type){
          //TM_SQDIFF Matching Method
          case TM_SQDIFF:
              Imgproc.matchTemplate(mROI, mTemplate, mResult, Imgproc.TM_SQDIFF); 
              break;
          //TM_SQDIFF Matching Method
          case TM_SQDIFF_NORMED:
              Imgproc.matchTemplate(mROI, mTemplate, mResult, Imgproc.TM_SQDIFF_NORMED); 
              break;
          //TM_SQDIFF Matching Method 
          case TM_CCOEFF:
              Imgproc.matchTemplate(mROI, mTemplate, mResult, Imgproc.TM_CCOEFF); 
              break;
          //TM_SQDIFF Matching Method             
          case TM_CCOEFF_NORMED:
              Imgproc.matchTemplate(mROI, mTemplate, mResult, Imgproc.TM_CCOEFF_NORMED) ; 
              break;
          //TM_SQDIFF Matching Method                 
          case TM_CCORR:
              Imgproc.matchTemplate(mROI, mTemplate, mResult, Imgproc.TM_CCORR) ; 
              break;
          //TM_SQDIFF Matching Method             
          case TM_CCORR_NORMED:
              Imgproc.matchTemplate(mROI, mTemplate, mResult, Imgproc.TM_CCORR_NORMED) ; 
              break;
      }

      Core.MinMaxLocResult mmres =  Core.minMaxLoc(mResult);

      // there is difference in matching methods - best match is max/min value
      if(type == TM_SQDIFF || type == TM_SQDIFF_NORMED)
      { 
          matchLoc = mmres.minLoc; 
      }
      else  
      { 
          matchLoc = mmres.maxLoc; 
      }

      Point  matchLoc_tx = new Point(matchLoc.x+area.x,matchLoc.y+area.y);
      Point  matchLoc_ty = new Point(matchLoc.x + mTemplate.cols() + area.x , matchLoc.y + mTemplate.rows()+area.y );

      Core.rectangle(mRgba, matchLoc_tx,matchLoc_ty, new Scalar(255,255, 255, 255) ,2);

      if(type == TM_SQDIFF || type == TM_SQDIFF_NORMED){ 
          return mmres.maxVal; 
      }
      else { 
          return mmres.minVal; 
      }

    }
 }

FdActivity 类

public class FdActivity extends Activity {

private static final String TAG = "Sample::Activity";

private MenuItem mItemFace50;
private MenuItem mItemFace40;
private MenuItem mItemFace30;
private MenuItem mItemFace20;
private MenuItem mItemType;
private FdView mView;

//Popup Window
private LayoutInflater inflater;
private PopupWindow pw;
private View popupView;

public static int method = 1;

//Timer Initializer
public int timer_start = 25000;

//Address Initializer
private String Address_location = "Ramakrishna Road, Colombo 00600, Sri Lanka";

//Sound Alerts
private MediaPlayer warning_sound;
private MediaPlayer lowbattery_alert;

private BaseLoaderCallback mOpenCVCallBack = new BaseLoaderCallback(this) {
    @SuppressWarnings("deprecation")
    @Override
    public void onManagerConnected(int status) {
        switch (status) {
        case LoaderCallbackInterface.SUCCESS: {
            Log.i(TAG, "OpenCV loaded successfully");

            //Load native libs after OpenCV initialization
            System.loadLibrary("detection_based_tracker");

            // Create and set View          
            mView = new FdView(mAppContext);
            mView.setDetectorType(mDetectorType);
            mView.setMinFaceSize(0.2f);

            //Start Tracking btn
            Button btn_track = new Button(getApplicationContext());
            btn_track.setText("Settings");
            btn_track.setBackgroundResource(R.drawable.custombutton_settings);
            btn_track.setTextColor(Color.WHITE);
            btn_track.setTypeface(null, Typeface.BOLD);

            RelativeLayout.LayoutParams btnp = new RelativeLayout.LayoutParams(
            RelativeLayout.LayoutParams.WRAP_CONTENT,
            RelativeLayout.LayoutParams.WRAP_CONTENT);
            btnp.addRule(RelativeLayout. ALIGN_PARENT_RIGHT);
            btn_track.setId(2);

            btn_track.setOnClickListener(new OnClickListener() {
                public void onClick(View v) {

                    //Popup Menu
                    pw = new PopupWindow(getApplicationContext());
                    pw.setTouchable(true);
                    pw.setFocusable(true);
                    pw.setOutsideTouchable(true);
                    pw.setTouchInterceptor(new OnTouchListener() {
                        public boolean onTouch(View v, MotionEvent event) {
                            if (event.getAction() == MotionEvent.ACTION_OUTSIDE) {
                                pw.dismiss();

                                return true;
                            }

                            return false;
                        }
                    });

                    pw.setWidth(WindowManager.LayoutParams.WRAP_CONTENT);
                    pw.setHeight(WindowManager.LayoutParams.WRAP_CONTENT);
                    pw.setOutsideTouchable(false);
                    pw.setContentView(popupView);
                    pw.showAsDropDown(v, 0, 0);
                }
            });

            final TextView count_down = new TextView(getApplicationContext());
            count_down.setText("Driver's State Recognition System");
            count_down.setGravity(Gravity.CENTER);
            count_down.setBackgroundColor(Color.BLACK);
            count_down.setTextColor(Color.WHITE);
            count_down.setTypeface(null, Typeface.BOLD);

            RelativeLayout.LayoutParams textTimer = new RelativeLayout.LayoutParams(
            RelativeLayout.LayoutParams.WRAP_CONTENT,
            RelativeLayout.LayoutParams.WRAP_CONTENT);
            textTimer.setMargins(30, 0, 0, 30);

            textTimer.addRule(RelativeLayout. ALIGN_PARENT_BOTTOM);
            count_down.setId(6);

            //Count Timer
            final CountDownTimer cntr_aCounter = new CountDownTimer(timer_start, 1000) {
                public void onTick(long millisUntilFinished) {
                }
                public void onFinish() {

                    //Start Alert Sound
                    warning_sound.start();
                    warning_sound.setLooping(true);
                    Toast.makeText(getBaseContext(), "Alerting Started...", Toast.LENGTH_LONG).show();

                    //Start Vibration
                    final Vibrator vibe = (Vibrator)getSystemService(VIBRATOR_SERVICE);
                    vibe.vibrate(20000);

                    //Start Alert Box and Emergency Text Alert
                    final AlertDialog alertDialog_warning = new AlertDialog.Builder(FdActivity.this).create();
                    alertDialog_warning.setCancelable(false);
                    alertDialog_warning.setTitle("WARNING");
                    alertDialog_warning.setMessage("Drowsiness Detected..Please Respond");
                    alertDialog_warning.setIcon(R.drawable.warning_icon);
                    alertDialog_warning.setButton("Respond", new DialogInterface.OnClickListener() {

                        final  CountDownTimer timer_count_down = new CountDownTimer(25000, 1000) {

                             public void onTick(long millisUntilFinished) {
                                 count_down.setText("Seconds Remaining To Respond : " + millisUntilFinished / 1000);
                             }

                             public void onFinish() {

                                    //Emergency Text Alert
                                    String phoneNo = "0712055056";
                                    String sms = "Emergancy Alert !...Location : " + Address_location;
                                    try {
                                        SmsManager smsManager = SmsManager.getDefault();
                                        smsManager.sendTextMessage(phoneNo, null, sms, null, null);
                                        Toast.makeText(getApplicationContext(), "Emergancy Alert Sent !",Toast.LENGTH_LONG).show();
                                    } 
                                    catch (Exception e) {
                                        Toast.makeText(getApplicationContext(),"Emergancy Alert  Sending Failed",Toast.LENGTH_LONG).show();
                                        e.printStackTrace();
                                    }

                                //Stop all active alerts
                                 count_down.setText("Not Responded Emergancy Alert Sent");
                                 Animation anim = new AlphaAnimation(0.0f, 1.0f);
                                 anim.setDuration(50); //You can manage the time of the blink with this parameter
                                 anim.setStartOffset(20);
                                 anim.setRepeatMode(Animation.REVERSE);
                                 anim.setRepeatCount(Animation.INFINITE);
                                 count_down.startAnimation(anim);
                                 count_down.setTextColor(Color.RED);
                                 alertDialog_warning.cancel();
                                 warning_sound.pause();
                                 vibe.cancel();
                                 timer_count_down.cancel();
                             }
                          }.start();
                        public void onClick(final DialogInterface alertDialog_warning, final int which) {
                            alertDialog_warning.cancel();
                            //Stop Alert Sound
                            warning_sound.pause();
                            vibe.cancel();
                            timer_count_down.cancel();
                            count_down.setText("Driver's State Recognition System");
                            finish();
                            startActivity(getIntent());
                        }
                    });
                    alertDialog_warning.show();
                }
            };
            cntr_aCounter.start();

            //Turn off btn
            Button btn_off = new Button(getApplicationContext());
            btn_off.setText("Switch Off");
            btn_off.setBackgroundResource(R.drawable.custombutton_settings);
            btn_off.setTextColor(Color.WHITE);
            btn_off.setTypeface(null, Typeface.BOLD);

            RelativeLayout.LayoutParams btnp1 = new RelativeLayout.LayoutParams(
            RelativeLayout.LayoutParams.WRAP_CONTENT,
            RelativeLayout.LayoutParams.WRAP_CONTENT);
            btnp1.addRule(RelativeLayout. ALIGN_PARENT_LEFT);
            btn_off.setId(3);

            btn_off.setOnClickListener(new OnClickListener() {
                public void onClick(View x) {

                    //Alert Dialog Box
                    AlertDialog.Builder alertDialog = new AlertDialog.Builder(FdActivity.this);

                    alertDialog.setTitle("WARNING");
                    alertDialog.setMessage(" Switch off Drowsiness Detection. \n Are you sure ?");
                    alertDialog.setIcon(R.drawable.warning_icon);
                    alertDialog.setCancelable(false); // This blocks the 'BACK' button

                    // Setting "Yes" Btn
                    alertDialog.setPositiveButton("YES",
                            new DialogInterface.OnClickListener() {
                                public void onClick(DialogInterface dialog, int which) {
                                    finish();
                                    cntr_aCounter.cancel();
                                }
                            });

                    // Setting "NO" Btn
                    alertDialog.setNegativeButton("NO",
                            new DialogInterface.OnClickListener() {
                                public void onClick(DialogInterface dialog, int which) {
                                    Toast.makeText(getApplicationContext(),"Tracking Process Continued", Toast.LENGTH_LONG).show();
                                    dialog.cancel();
                                }
                            });
                    alertDialog.show();
                }
            });

            RelativeLayout frameLayout = new RelativeLayout(
            getApplicationContext());
            frameLayout.addView(mView, 0);
            frameLayout.addView(btn_track, btnp);
            frameLayout.addView(btn_off, btnp1);
            frameLayout.addView(count_down, textTimer);



            setContentView(frameLayout);

            // Check native OpenCV camera
            if (!mView.openCamera()) {
                AlertDialog ad = new AlertDialog.Builder(mAppContext).create();
                ad.setCancelable(false); // This blocks the 'BACK' button
                ad.setMessage("Fatal Error: Can't Open Camera!");
                ad.setButton("OK", new DialogInterface.OnClickListener() {
                    public void onClick(DialogInterface dialog, int which) {
                        dialog.dismiss();
                        finish();
                    }
                });
                ad.show();
            }
        }
            break;
        default: {
            super.onManagerConnected(status);
        }
            break;
        }
    }
};

private int mDetectorType = 0;
private String[] mDetectorName;

public FdActivity() {
    Log.i(TAG, "Instantiated new " + this.getClass());
    mDetectorName = new String[2];
    mDetectorName[FdView.JAVA_DETECTOR] = "Java";
    mDetectorName[FdView.NATIVE_DETECTOR] = "Native (tracking)";
}

@Override
protected void onPause() {
    Log.i(TAG, "onPause");
    super.onPause();
    if (mView != null)
        mView.releaseCamera();
}

@SuppressWarnings("deprecation")
@Override
protected void onResume() {
    Log.i(TAG, "onResume");
    super.onResume();
    if (mView != null && !mView.openCamera()) {
        AlertDialog ad = new AlertDialog.Builder(this).create();
        ad.setCancelable(false); // This blocks the 'BACK' button
        ad.setMessage("Fatal error: can't open camera!");
        ad.setButton("OK", new DialogInterface.OnClickListener() {
            public void onClick(DialogInterface dialog, int which) {
                dialog.dismiss();
                finish();
            }
        });
        ad.show();
    }
}

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    Log.i(TAG, "onCreate");
    super.onCreate(savedInstanceState);
    requestWindowFeature(Window.FEATURE_NO_TITLE);

    //Sound Alert
    warning_sound = MediaPlayer.create(this, R.raw.warning_alert);
    lowbattery_alert = MediaPlayer.create(this, R.raw.low_battery);

    //Popup menu
    inflater = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    popupView = inflater.inflate(R.layout.popup_menu_layout, null, false);

    Log.i(TAG, "Trying to load OpenCV library");
    if (!OpenCVLoader.initAsync(OpenCVLoader.OPENCV_VERSION_2_4_2, this,mOpenCVCallBack)) {
        Log.e(TAG, "Cannot connect to OpenCV Manager");
    }

    //battery
    this.registerReceiver(this.batteryInfoReceiver, new IntentFilter(Intent.ACTION_BATTERY_CHANGED));
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    Log.i(TAG, "onCreateOptionsMenu");
    mItemFace50 = menu.add("Face size 50%");
    mItemFace40 = menu.add("Face size 40%");
    mItemFace30 = menu.add("Face size 30%");
    mItemFace20 = menu.add("Face size 20%");
    mItemType = menu.add(mDetectorName[mDetectorType]);

    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    Log.i(TAG, "Menu Item selected " + item);
    if (item == mItemFace50)
        mView.setMinFaceSize(0.5f);
    else if (item == mItemFace40)
        mView.setMinFaceSize(0.4f);
    else if (item == mItemFace30)
        mView.setMinFaceSize(0.3f);
    else if (item == mItemFace20)
        mView.setMinFaceSize(0.2f);
    else if (item == mItemType) {
        mDetectorType = (mDetectorType + 1) % mDetectorName.length;
        item.setTitle(mDetectorName[mDetectorType]);
        mView.setDetectorType(mDetectorType);
    }
    return true;
}

//Popup Menu Actions
public void clickOne(View v) {
    pw.dismiss();
    mView.resetLearFramesCount();
    Toast.makeText(getApplicationContext(), "Please wait..Template Recreating", Toast.LENGTH_LONG).show();
}

public void clickTwo(View v) {
    pw.dismiss();
    Toast.makeText(getBaseContext(), "Please wait..Switching Camera", Toast.LENGTH_LONG).show();
}

public void clickThree(View v) {
    pw.dismiss();
    Toast.makeText(getBaseContext(), "Please wait..Changing Tracking Method", Toast.LENGTH_LONG).show();
}

public void clickFour(View v) {
    pw.dismiss();
    Toast.makeText(getBaseContext(), "Please wait..Changing Tracking Method", Toast.LENGTH_LONG).show();

    //Alert Dialog Box
    AlertDialog.Builder alertDialog = new AlertDialog.Builder(FdActivity.this);
    alertDialog.setCancelable(false);
    alertDialog.setTitle("Exit Detection");
    alertDialog.setMessage(" WARNING...You are about to exit system");
    alertDialog.setIcon(R.drawable.warning_icon);

    alertDialog.setPositiveButton("Continue", new DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog, int which) {
                    dialog.cancel();
                }
            });

    alertDialog.setNegativeButton("System Settings", new DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog, int which) {
                    dialog.cancel();
                    finish();
                    startActivity(new Intent("org.opencv.samples.facedetect.CLEARSCREENSETTINGS"));
                }
            });
    alertDialog.show();
}

private BroadcastReceiver batteryInfoReceiver = new BroadcastReceiver() {
    @Override
    public void onReceive(Context context, Intent intent) {
        int  level= intent.getIntExtra(BatteryManager.EXTRA_LEVEL,0);
        int  plugged= intent.getIntExtra(BatteryManager.EXTRA_PLUGGED,0);

        if(plugged==1){
            Toast.makeText(getApplicationContext(), "Device Pluged In", Toast.LENGTH_LONG).show();
            lowbattery_alert.pause();
        }

        if(plugged==0 && level > 20){
            Toast.makeText(getApplicationContext(), "WARNING : Device Not Pluged In", Toast.LENGTH_LONG).show();
            lowbattery_alert.pause();
        }

        else if(plugged==0 && level <= 20){
            Toast.makeText(getApplicationContext(), "WARNING : Battery Low Please Plug In", Toast.LENGTH_LONG).show();

            //alert sound
            lowbattery_alert.start();

            //Start Vibration
            final Vibrator vibe = (Vibrator)getSystemService(VIBRATOR_SERVICE);
            vibe.vibrate(20000);

            //Alert Dialog Box
            AlertDialog.Builder alertDialog = new AlertDialog.Builder(FdActivity.this);
            alertDialog.setCancelable(false);
            alertDialog.setTitle("Battery Low (" + level + "%)");
            alertDialog.setMessage(" WARNING...Battery Low Please Connect The Charger");
            alertDialog.setIcon(R.drawable.warning_icon);

            // Setting "Switch Off" Btn
            alertDialog.setPositiveButton("Switch Off", new DialogInterface.OnClickListener() {
                        public void onClick(DialogInterface dialog, int which) {
                            finish();
                            lowbattery_alert.pause();
                            vibe.cancel();
                        }
                    });
            // Setting "Continue" Btn
            alertDialog.setNegativeButton("Continue", new DialogInterface.OnClickListener() {
                        public void onClick(DialogInterface dialog, int which) {
                            Toast.makeText(getApplicationContext(),"Tracking Process Continued", Toast.LENGTH_LONG).show();
                            dialog.cancel();
                            vibe.cancel();
                            lowbattery_alert.pause();
                        }
                    });
            alertDialog.show();
        }
    }
};

public void onBackPressed() {
    Toast.makeText(getBaseContext(), "Please click Switch off button to deactivate the system", Toast.LENGTH_LONG).show();
}
}

Answer 1

据我了解，您有Activity，您希望在其中显示您希望从另一个类获得的两个值。您不能从一个函数返回两个值，这就是为什么我建议您创建自己的 Object 来保存这些值，并且您可以从 match_eye() 返回自定义对象例如，从您的 Activity 中获取您的值。这是示例代码:

MyCustomObject.java

public MyObject{

    private int mFirstValue;
    private int mSecondValue;

    // public constructor
    public MyObject(int firstValue, int secondValue){
         this.mFirstValue = firstValue;
         this.mSecondValue = secondValue;
    }

    // first value getter
    public int getFirstValue(){
        return mFirstValue;
    }

    // second value getter;
    public int getSecondValue(){
        return mSecondValue;
    }
}

在您的 match_eye() 中，您可以执行类似的操作:

public MyObject match_eye(Rect area, Mat mTemplate,int type){

        //do your calculations here ...
        int firstValue = 0; // get first value
        int secondValue = 0; // get second value

   return new MyObject(firstValue, secondValue); 
}

在您的Activity中，您只需调用:

MyObject mCurrentObject = FdView.match_eye(/*params*/); // static call as example
if(mCurrentObject != null){
     int myFirstValue = mCurrentObject.getFirstValue();
     int mySecondValue = mCurrentObject.getSecondValue();
     // Show these values in your Activity.
}