I am doing face detection application using opencv.the app is installed in the phone but due to fatal error it get closed suddenly. this is my MainActivity.java
package com.example.oc2;
import androidx.appcompat.app.AppCompatActivity;
import android.content.Context;
import android.os.Bundle;
import org.opencv.android.BaseLoaderCallback;
import org.opencv.android.CameraActivity;
import org.opencv.android.CameraBridgeViewBase;
import org.opencv.android.CameraBridgeViewBase.CvCameraViewFrame;
import org.opencv.android.LoaderCallbackInterface;
import org.opencv.android.OpenCVLoader;
import org.opencv.core.Mat;
import org.opencv.android.CameraBridgeViewBase.CvCameraViewListener2;
import org.opencv.android.CameraBridgeViewBase;
import org.opencv.android.JavaCameraView;
import org.opencv.core.Mat;
import org.opencv.core.MatOfRect;
import org.opencv.core.Point;
import org.opencv.core.Rect;
import org.opencv.core.Scalar;
import org.opencv.imgproc.Imgproc;
import org.opencv.objdetect.CascadeClassifier;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
public class MainActivity extends AppCompatActivity implements CameraBridgeViewBase.CvCameraViewListener2{
JavaCameraView javaCameraView;
File cascfile;
CascadeClassifier facedetector;
private Mat mRgba,mGrey;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
if(!OpenCVLoader.initDebug())
{
OpenCVLoader.initAsync(OpenCVLoader.OPENCV_VERSION_3_4_0,this, baseCallback);
}
else
{
try {
baseCallback.onManagerConnected(LoaderCallbackInterface.SUCCESS);
} catch (IOException e) {
e.printStackTrace();
}
}
javaCameraView.setCvCameraViewListener(this);
}
@Override
public void onCameraViewStarted(int width, int height) {
mRgba=new Mat();
mGrey=new Mat();
}
@Override
public void onCameraViewStopped() {
mGrey.release();
mRgba.release();
}
@Override
public Mat onCameraFrame(CameraBridgeViewBase.CvCameraViewFrame inputFrame) {
mRgba=inputFrame.rgba();
mGrey=inputFrame.gray();
MatOfRect facedetection= new MatOfRect();
facedetector.detectMultiScale(mRgba,facedetection);
for(Rect rect: facedetection.toArray())
{
Imgproc.rectangle(mRgba,new Point(rect.x,rect.y),new Point(rect.x+rect.width,rect.y+rect.height),new Scalar(255,0,0));
}
return mRgba;
}
private final BaseLoaderCallback baseCallback=new BaseLoaderCallback(this) {
@Override
public void onManagerConnected(int status) throws IOException {
switch (status)
{
case LoaderCallbackInterface.SUCCESS:
{
InputStream is = getResources().openRawResource(R.raw.haarcascade_frontalface_alt2);
File cascadedir=getDir( "cascade" , Context.MODE_PRIVATE);
cascfile= new File(cascadedir, "haarcascade_frontalface_alt2.xml" );
FileOutputStream fos= new FileOutputStream(cascfile);
byte[] buffer=new byte[4096];
int bytesread;
while((bytesread = is.read(buffer))!=-1)
{
fos.write(buffer,0,bytesread);
}
is.close();
fos.close();
facedetector=new CascadeClassifier(cascfile.getAbsolutePath());
if(facedetector.empty())
{
facedetector=null;
}
else
{
cascadedir.delete();
}
javaCameraView.enableView();
}
break;
default:
{
super.onManagerConnected(status);
}
break;
}
}
};
}
this are my errors can anyone help?
D/AndroidRuntime: Shutting down VM E/AndroidRuntime: FATAL EXCEPTION: main Process: com.example.oc2, PID: 19468 java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.oc2/com.example.oc2.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void org.opencv.android.JavaCameraView.enableView()' on a null object reference at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2984) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3119) at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:78) at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:108) at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:68) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1839) at android.os.Handler.dispatchMessage(Handler.java:106) at android.os.Looper.loop(Looper.java:201) at android.app.ActivityThread.main(ActivityThread.java:6864) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:547) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:873) Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void org.opencv.android.JavaCameraView.enableView()' on a null object reference at com.example.oc2.MainActivity$1.onManagerConnected(MainActivity.java:116) at com.example.oc2.MainActivity.onCreate(MainActivity.java:52) at android.app.Activity.performCreate(Activity.java:7232) at android.app.Activity.performCreate(Activity.java:7221) at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1272) at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2964) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3119) at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:78) at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:108) at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:68) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1839) at android.os.Handler.dispatchMessage(Handler.java:106) at android.os.Looper.loop(Looper.java:201) at android.app.ActivityThread.main(ActivityThread.java:6864) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:547) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:873) I/Process: Sending signal. PID: 19468 SIG: 9
if anyone could give steps to resolving the errors it would be very helpful.
1条答案
按热度按时间olhwl3o21#
我对你的代码有两种感觉:
1 -在您的
onCreate
练习中,您缺少一行:2 -您未检查是否已授予摄像机权限,这可能会导致稍后出现另一个错误[
"it seems that your device does not support camera or it is locked - application will be closed"
]因此,请使用此代码片段进行测试,但请注意,要使其正常工作,您需要在启动应用程序[
Settings->Apps->YourApp->Permissions->Camera
]之前启用应用程序的摄像头权限。权限部分必须为rewritten properly,这只是一个快速测试