我想要做的是在检测到笑容时解除警报。首先当闹铃响起时，它会转到这个类AlarmScreen.java。然后，用户将单击微笑按钮以打开第二个活动，即MainActivity.java，它将打开相机活动。
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Intent alarmIntent = new Intent(AlarmScreen.this, AlarmManagerHelper.class);
pendingIntent = PendingIntent.getBroadcast(AlarmScreen.this, 0, alarmIntent, 0);
//Setup layout
this.setContentView(R.layout.activity_alarm_screen);
String name = getIntent().getStringExtra(AlarmManagerHelper.NAME);
int timeHour = getIntent().getIntExtra(AlarmManagerHelper.TIME_HOUR, 0);
int timeMinute = getIntent().getIntExtra(AlarmManagerHelper.TIME_MINUTE, 0);
String tone = getIntent().getStringExtra(AlarmManagerHelper.TONE);
TextView tvName = (TextView) findViewById(R.id.alarm_screen_name);
tvName.setText(name);
TextView tvTime = (TextView) findViewById(R.id.alarm_screen_time);
tvTime.setText(String.format("%02d : %02d", timeHour, timeMinute));
Button dismissButton = (Button) findViewById(R.id.alarm_screen_button);
dismissButton.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View view) {
mPlayer.stop();
finish();
}
});
Button camera = (Button) findViewById(R.id.camera);
camera.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View view) {
Intent intent = new Intent(getApplicationContext(), MainActivity.class);
intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(intent);
}
});
public void stopAlarm() {
Button dismissButton = (Button) findViewById(R.id.alarm_screen_button);
dismissButton.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View view) {
mPlayer.stop();
finish();
}
});
}
mPlayer = new MediaPlayer();
try {
if (tone != null && !tone.equals("")) {
Uri toneUri = Uri.parse(tone);
if (toneUri != null) {
mPlayer.setDataSource(this, toneUri);
mPlayer.setAudioStreamType(AudioManager.STREAM_ALARM);
mPlayer.setLooping(true);
mPlayer.prepare();
mPlayer.start();
}
}
} catch (Exception e) {
e.printStackTrace();
}
这是MainActivity.java类，其中所有检测都在此处进行。
public void onPreviewFrame(byte[] data, Camera camera) {
int surfaceWidth = mPreview.getWidth();
int surfaceHeight = mPreview.getHeight();
faceProc.normalizeCoordinates(surfaceWidth, surfaceHeight);
numFaces = faceProc.getNumFaces();
int dRotation = display.getRotation();
PREVIEW_ROTATION_ANGLE angleEnum = PREVIEW_ROTATION_ANGLE.ROT_0;
if (numFaces > 0) {
System.out.println("face detected");
Log.d("TAG", "Face Detected");
faceArray = faceProc.getFaceData();
preview.removeView(drawView);
drawView = new DrawView(this, faceArray, true);
preview.addView(drawView);
} else {
preview.removeView(drawView);
drawView = new DrawView(this, null, false);
preview.addView(drawView);
}
在这个类上，它将在嘴部区域绘制圆圈。在圆圈变为绿色后，它将调用另一个活动，即Dismiss.java类。
public class DrawView extends SurfaceView {
public FaceData []mFaceArray;
boolean _inFrame;
private Paint mouthBrush = new Paint();
private Paint rectBrush = new Paint();
public Point mouth;
Rect mFaceRect;
AlarmService A;
AlarmScreen B;
Paint paint = new Paint();
}
public DrawView(Context context,FaceData []faceArray, boolean inFrame){
super(context);
setWillNotDraw(false);
mFaceArray = faceArray;
_inFrame = inFrame;
}
protected void onDraw(Canvas canvas) {
if(_inFrame){
for(int i = 0; i<mFaceArray.length; i++){
setCircleColor(mFaceArray[i], mouthBrush);
canvas.drawCircle(mFaceArray[i].mouth.x, mFaceArray[i].mouth.y, 20f, mouthBrush);
}
}else{
canvas.drawColor(0, Mode.CLEAR);
}
}
private void setCircleColor(FaceData faceData, Paint rectBrush) {
if(faceData.getSmileValue()<80){
mouthBrush.setColor(Color.RED);
}else{
mouthBrush.setColor(Color.GREEN);
startActivity(getContext());
}
}
public void startActivity(Context mContext){
Intent intent = new Intent(mContext,Dismiss.class);
mContext.startActivity(intent);
}
这是我应该关闭警报的活动类，通过从AlarmScreen.java类调用stopAlarm（）方法，警报被解除，不幸的是应用程序在这里停止。我是这个领域的新手，我不太清楚错误发生的原因。有人能帮助我吗？
public class Dismiss extends Activity {
public static Activity AlarmScreen;
private MediaPlayer mPlayer;
AlarmService A;
AlarmScreen B;
AlarmRing C;
@Override
Protected void onCreate (final Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
this.setContentView(R.layout.dismiss);
Button dismissButton = (Button) findViewById(R.id.dismiss);
dismissButton.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View view) {
B.stopAlarm();
finish();
}
});
}
}
我不知道如何显示logcat，因为我还是新手，但现在是。
06-03 19:40:10.400: E/AndroidRuntime(31323): FATAL EXCEPTION: main
06-03 19:40:10.400: E/AndroidRuntime(31323): Process: com.trigg.alarmclock, PID: 31323
06-03 19:40:10.400: E/AndroidRuntime(31323): java.lang.NullPointerException
06-03 19:40:10.400: E/AndroidRuntime(31323): at com.smileclock.Dismiss$1.onClick(Dismiss.java:61)
06-03 19:40:10.400: E/AndroidRuntime(31323): at android.view.View.performClick(View.java:4569)
06-03 19:40:10.400: E/AndroidRuntime(31323): at android.view.View$PerformClick.run(View.java:18553)
06-03 19:40:10.400: E/AndroidRuntime(31323): at android.os.Handler.handleCallback(Handler.java:733)
06-03 19:40:10.400: E/AndroidRuntime(31323): at android.os.Handler.dispatchMessage(Handler.java:95)
06-03 19:40:10.400: E/AndroidRuntime(31323): at android.os.Looper.loop(Looper.java:212)
06-03 19:40:10.400: E/AndroidRuntime(31323): at android.app.ActivityThread.main(ActivityThread.java:5135)
06-03 19:40:10.400: E/AndroidRuntime(31323): at java.lang.reflect.Method.invokeNative(Native Method)
06-03 19:40:10.400: E/AndroidRuntime(31323): at java.lang.reflect.Method.invoke(Method.java:515)
06-03 19:40:10.400: E/AndroidRuntime(31323): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:877)
06-03 19:40:10.400: E/AndroidRuntime(31323): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:693)
06-03 19:40:10.400: E/AndroidRuntime(31323): at dalvik.system.NativeStart.main(Native Method)
06-03 19:40:11.750: I/Process(31323): Sending signal. PID: 31323 SIG: 9
06-03 19:40:11.860: E/MediaPlayer-JNI(32419): QCMediaPlayer mediaplayer NOT present
06-03 19:40:11.900: D/AndroidRuntime(32419): Shutting down VM
06-03 19:40:11.900: W/dalvikvm(32419): threadid=1: thread exiting with uncaught exception (group=0x41613d88)
06-03 19:40:11.900: E/AndroidRuntime(32419): FATAL EXCEPTION: main
06-03 19:40:11.900: E/AndroidRuntime(32419): Process: com.trigg.alarmclock, PID: 32419
06-03 19:40:11.900: E/AndroidRuntime(32419): java.lang.RuntimeException: Unable to start service com.smileclock.AlarmService@447f7488 with null: java.lang.NullPointerException
06-03 19:40:11.900: E/AndroidRuntime(32419): at android.app.ActivityThread.handleServiceArgs(ActivityThread.java:2767)
06-03 19:40:11.900: E/AndroidRuntime(32419): at android.app.ActivityThread.access$2100(ActivityThread.java:144)
06-03 19:40:11.900: E/AndroidRuntime(32419): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1343)
06-03 19:40:11.900: E/AndroidRuntime(32419): at android.os.Handler.dispatchMessage(Handler.java:102)
06-03 19:40:11.900: E/AndroidRuntime(32419): at android.os.Looper.loop(Looper.java:212)
06-03 19:40:11.900: E/AndroidRuntime(32419): at android.app.ActivityThread.main(ActivityThread.java:5135)
06-03 19:40:11.900: E/AndroidRuntime(32419): at java.lang.reflect.Method.invokeNative(Native Method)
06-03 19:40:11.900: E/AndroidRuntime(32419): at java.lang.reflect.Method.invoke(Method.java:515)
06-03 19:40:11.900: E/AndroidRuntime(32419): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:877)
06-03 19:40:11.900: E/AndroidRuntime(32419): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:693)
06-03 19:40:11.900: E/AndroidRuntime(32419): at dalvik.system.NativeStart.main(Native Method)
06-03 19:40:11.900: E/AndroidRuntime(32419): Caused by: java.lang.NullPointerException
06-03 19:40:11.900: E/AndroidRuntime(32419): at android.content.Intent.putExtras(Intent.java:6134)
06-03 19:40:11.900: E/AndroidRuntime(32419): at com.smileclock.AlarmService.onStartCommand(AlarmService.java:21)
06-03 19:40:11.900: E/AndroidRuntime(32419): at android.app.ActivityThread.handleServiceArgs(ActivityThread.java:2750)
答案 0 :(得分：0)
从您发布的代码中，以下行将抛出空指针异常，因为您的代码似乎没有初始化B
B.stopAlarm();
如果要在AlarmScreen类上调用此方法，则必须初始化B以引用该类型的对象。您可以将AlarmScreen对象传递给类Dismiss
或者，您可以从B.stopAlarm()类中取出对Dismiss的调用，并从父活动中调用它，该活动可能具有对AlarmScreen的有效引用。