[Java for Android App Development] deniel:
Im trying to start a simple app and i need to display on a SurfaceView the preview of the cam as soon as the App start.

i added the permission to the manifest:

<uses-permission android:name="android.permission.CAMERA" />

<uses-feature android:name="android.hardware.camera" />

and my code:

import android.content.Context;
import android.hardware.Camera;
import android.view.SurfaceHolder;
import android.view.SurfaceView;

public class MainActivity extends SurfaceView implements SurfaceHolder.Callback{

SurfaceView mSurfaceView;
private SurfaceHolder mHolder;
public Camera camera = null;

public MainActivity(Context context) {
super(context);

mSurfaceView = (SurfaceView) findViewById(R.id.surfaceView);
mHolder = mSurfaceView.getHolder();
mHolder.addCallback(this);
mHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);

}

[MENTION=439709]override[/MENTION]
public void surfaceCreated(SurfaceHolder holder) {
camera = Camera.open();

try{
camera.setPreviewDisplay(mHolder);
} catch(Exception e){

}
}

[MENTION=439709]override[/MENTION]
public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
Camera.Parameters params = camera.getParameters();
params.setPreviewSize(width,height);
camera.setParameters(params);
camera.startPreview();
}

[MENTION=439709]override[/MENTION]
public void surfaceDestroyed(SurfaceHolder holder) {
camera.stopPreview();
camera = null;
}
}

Ive looked for many tutorial and all technically do the same or smiliart stuff. But the app crashes. I cant find a solution

LogCat

06-01 12:39:12.456 616-841/system_process I/ActivityManager: START u0 {act=android.intent.action.MAIN cat=[android.intent.category.LAUNCHER] flg=0x10200000 cmp=com.example.droidcam/.MainActivity bnds=[240,408][240,408]} from pid 861
06-01 12:39:12.596 616-841/system_process D/dalvikvm: GC_FOR_ALLOC freed 1352K, 16% free 11518K/13560K, paused 112ms, total 118ms
06-01 12:39:12.636 2744-2744/? D/dalvikvm: Late-enabling CheckJNI
06-01 12:39:12.646 616-881/system_process I/ActivityManager: Start proc com.example.droidcam for activity com.example.droidcam/.MainActivity: pid=2744 uid=10019 gids={50019, 1006, 1028}
06-01 12:39:12.746 2744-2744/com.example.droidcam E/Trace: error opening trace file: No such file or directory (2)
06-01 12:39:12.826 2744-2744/com.example.droidcam D/dalvikvm: newInstance failed: no <init>()
06-01 12:39:12.836 2744-2744/com.example.droidcam D/AndroidRuntime: Shutting down VM
06-01 12:39:12.836 2744-2744/com.example.droidcam W/dalvikvm: threadid=1: thread exiting with uncaught exception (group=0x2b5d9930)
06-01 12:39:12.836 2744-2744/com.example.droidcam E/AndroidRuntime: FATAL EXCEPTION: main
java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.droidcam/com.example.droidcam.MainActivity}: java.lang.InstantiationException: can't instantiate class com.example.droidcam.MainActivity; no empty constructor
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2223)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2357)
at android.app.ActivityThread.access$600(ActivityThread.java:153)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1247)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:5226)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:795)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:562)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.InstantiationException: can't instantiate class com.example.droidcam.MainActivity; no empty constructor
at java.lang.Class.newInstanceImpl(Native Method)
at java.lang.Class.newInstance(Class.java:1319)
at android.app.Instrumentation.newActivity(Instrumentation.java:1054)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2214)
... 11 more
06-01 12:39:12.836 616-1341/system_process W/ActivityManager: Force finishing activity com.example.droidcam/.MainActivity
06-01 12:39:12.986 616-650/system_process D/dalvikvm: GC_FOR_ALLOC freed 1696K, 24% free 10472K/13772K, paused 76ms, total 77ms
06-01 12:39:13.387 616-647/system_process W/ActivityManager: Activity pause timeout for ActivityRecord{2bd8aff0 u0 com.example.droidcam/.MainActivity}
06-01 12:39:18.952 2744-2744/? I/Process: Sending signal. PID: 2744 SIG: 9
06-01 12:39:18.952 616-943/system_process I/ActivityManager: Process com.example.droidcam (pid 2744) has died.
06-01 12:39:19.002 616-616/system_process W/InputMethodManagerService: Window already focused, ignoring focus gain of: com.android.internal.view.IInputMethodClient$Stub$Proxy@2b927ce0 attribute=null, token = android.os.BinderProxy@2ba93ee8