Java 设置内容视图（android程序）有问题

我在尝试向相机预览框添加按钮时遇到了一些问题，我发现当我添加这一行setContentViewR.layout.main时；我的程序崩溃了。 下面是我的代码和main.xml。请注意，xml是默认生成的，没有修改任何内容

我的代码

    package camera.test;
    import android.app.Activity;
    import android.content.Context;
    import android.content.Intent;
    import android.content.pm.ActivityInfo;
    import android.graphics.Bitmap;
    import android.graphics.Bitmap.CompressFormat;
    import android.graphics.Bitmap.Config;
    import android.graphics.BitmapFactory;
    import android.graphics.Canvas;
    import android.graphics.Color;
    import android.graphics.Paint;
    import android.graphics.Point;
    import android.graphics.Rect;
    import android.hardware.Camera;
    import android.hardware.Camera.PreviewCallback;
    import android.hardware.Camera.Size;
    import android.os.Bundle;
    import android.os.Environment;
    import android.view.Display;
    import android.view.SurfaceHolder;
    import android.view.SurfaceView;
    import android.view.View;
    import android.view.View.OnClickListener;
    import android.view.ViewGroup;
    import android.view.ViewGroup.LayoutParams;
    import android.view.Window;
    import android.view.WindowManager;
    import android.widget.Button;
    import java.io.BufferedOutputStream;
    import java.io.File;
    import java.io.FileNotFoundException;
    import java.io.FileOutputStream;
    import java.io.IOException;
    import java.util.List;
    import java.util.logging.Level;
    import java.util.logging.Logger;

    public class MainActivity extends Activity 
    { 
        Camera mCamera;
        private Preview mPreview;
        private DrawOnTop mDraw;
        private CameraConfigurationManager manager;
        Display display;
        public static Point screenResolution, cameraResolution;
        private Rect framingRect;
        private Rect framingRectInPreview;
        private Rect rect;
        private Camera.Parameters params;
        private Context mContext;
        public static String flag;

        private static final int MIN_FRAME_WIDTH = 240;
        private static final int MAX_FRAME_WIDTH = 300;
        private static final int MIN_FRAME_HEIGHT = 240;
        private static final int MAX_FRAME_HEIGHT = 200;
        /** Called when the activity is first created. */

@Override
public void onCreate(Bundle savedInstanceState)
{
    super.onCreate(savedInstanceState);
    //setContentView(R.layout.main); //if i add this line the app will crash

    requestWindowFeature(Window.FEATURE_NO_TITLE);
    getWindow().addFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN);
    setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);

    //params = Camera.getParameters();
    mContext = this;
    mPreview = new Preview(this);
    setContentView(mPreview);
    manager = new CameraConfigurationManager(this);
    Display display = ((WindowManager) this.getSystemService(Context.WINDOW_SERVICE)).getDefaultDisplay();
    screenResolution = new Point(display.getWidth(), display.getHeight());
    //cameraResolution = manager.getCameraResolution(params, screenResolution);
    rect = getFramingRect();       
    mDraw = new DrawOnTop(this, rect);

    addContentView(mDraw, new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT));

    //mCamera.takePicture(null, mPictureCallback, mPictureCallback);
}

public void onResume() {
    super.onResume();

    mCamera = Camera.open();
    mPreview.setCamera(mCamera);
}

public void onPause() {
    super.onPause();

    if(mCamera != null) {
        mPreview.setCamera(null);
        mCamera.release();
        mCamera = null;
    }
}

public static int leftOffset;
public Rect getFramingRect() {
if (framingRect == null) {
  if (mCamera == null) {
     flag = "its null";
     //return null;
  }
  //Point screenResolution = manager.getScreenResolution();
  int width = screenResolution.x *3/4;
  if (width < MIN_FRAME_WIDTH) {
    width = MIN_FRAME_WIDTH;
  } else if (width > MAX_FRAME_WIDTH) {
    width = MAX_FRAME_WIDTH;
  }
  int height = screenResolution.y * 3 / 4;
  if (height < MIN_FRAME_HEIGHT) {
    height = MIN_FRAME_HEIGHT;
  } else if (height > MAX_FRAME_HEIGHT) {
    height = MAX_FRAME_HEIGHT;
  }
  leftOffset = (screenResolution.x - width) / 2;
  int topOffset = (screenResolution.y - height) / 2;
  framingRect = new Rect(leftOffset, topOffset, leftOffset + width, topOffset + height);
  flag = framingRect.bottom+"";
  //Log.d(TAG, "Calculated framing rect: " + framingRect);*/
}
return framingRect;
}

public Rect getFramingrectInPreview() { //from zxing
    if(framingRectInPreview == null) {
        Rect rect = new Rect(getFramingRect());
        //Point p = manager.getCameraResolution();
        //Point p2 = manager.getScreenResolution();
        rect.left = rect.left * cameraResolution.x / screenResolution.x;
        rect.right = rect.right * cameraResolution.x / screenResolution.x;
        rect.top = rect.top * cameraResolution.y / screenResolution.y;
        rect.bottom = rect.bottom * cameraResolution.y / screenResolution.y;
        framingRectInPreview = rect;
    }
    return framingRectInPreview;
}
    }

    class DrawOnTop extends View {

//CameraConfigurationManager manager;
private Rect rect;

    public DrawOnTop(Context context, Rect rect1) {
    super(context);
    //manager = new CameraConfigurationManager(context);
    rect = rect1;
}

protected void onDraw(Canvas canvas) {


    //Rect rect = getFramingRect();
    //Point tt = manager.getCameraResolution();
    //int k = tt.y;
    Paint paint = new Paint();
    paint.setStyle(Paint.Style.FILL);


    paint.setColor(Color.WHITE);
    paint.setAlpha(100);
    canvas.drawRect(0, 0, rect.left, MainActivity.screenResolution.y, paint);
    canvas.drawRect(rect.right, 0, MainActivity.screenResolution.x, MainActivity.screenResolution.y, paint);
    canvas.drawRect(rect.left, 0, rect.right, rect.top, paint);
    canvas.drawRect(rect.left, rect.bottom, rect.right, MainActivity.screenResolution.y, paint);
    //paint.setAlpha(255);
    canvas.drawText(Preview.test1+"", 100, 100, paint);
    //canvas.drawRect(rect, paint);

    //canvas.drawPoint(rect.top, rect.left, paint);
    //canvas.drawCircle(rect.right,0, 10, paint);
    //canvas.drawRect(rect, paint);
    //canvas.drawColor(Color.GRAY);
    //paint.setAlpha(255);
    //canvas.drawCircle(10, 10, 10, paint);

    super.onDraw(canvas);
}
    }

    class Preview extends ViewGroup implements SurfaceHolder.Callback {
private final String TAG = "Preview";

SurfaceView mSurfaceView;
SurfaceHolder mHolder;
Size mPreviewSize;
List<Size> mSupportedPreviewSizes;
Camera mCamera;
public static int test1, test2;
//Display display;

Preview(Context context) {
    super(context);
     mSurfaceView = new SurfaceView(context);
     addView(mSurfaceView);

     mHolder = mSurfaceView.getHolder();
     mHolder.addCallback(this);
     mHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
     //display = ((WindowManager) context.getSystemService(Context.WINDOW_SERVICE)).getDefaultDisplay();
}

public void setCamera(Camera camera) {
    mCamera = camera;
    if(mCamera != null) {
        mSupportedPreviewSizes = mCamera.getParameters().getSupportedPreviewSizes();
        requestLayout();
    }
}

protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
    final int width = resolveSize(getSuggestedMinimumWidth(), widthMeasureSpec);
    final int height = resolveSize(getSuggestedMinimumHeight(), heightMeasureSpec);
    setMeasuredDimension(width, height);

    if(mSupportedPreviewSizes != null) {
        mPreviewSize = getOptimalPreviewSize(mSupportedPreviewSizes, width, height);
    }
}

protected void onLayout(boolean changed, int l, int t, int r, int b) {
    if (changed && getChildCount() > 0) {
        final View child = getChildAt(0);

        final int width = r - l;
        final int height = b - t;

        int previewWidth = width;
        int previewHeight = height;
        if(mPreviewSize != null) {
            previewWidth = mPreviewSize.width;
            previewHeight = mPreviewSize.height;
        }

        if(width*previewHeight > height * previewWidth) {
            final int scaledChildWidth = previewWidth * height / previewHeight;
            child.layout((width - scaledChildWidth) /2, 0, (width + scaledChildWidth) /2, height);
        }
        else {
            final int scaledChildHeight = previewHeight * width / previewWidth;
            child.layout(0, (height-scaledChildHeight) / 2, width, (height + scaledChildHeight) /2);
        }

    }

}

public void surfaceCreated(SurfaceHolder holder) {
    try {
        if(mCamera != null) {
            mCamera.setPreviewDisplay(holder);
        }
    }
    catch (IOException exception) {

    }
}

Camera.PreviewCallback mPreviewCallback = new Camera.PreviewCallback() {


                public void onPreviewFrame(byte[] data, Camera camera) {
                    test1 = 8889898;
                    //throw new UnsupportedOperationException("Not supported yet.");
                    int ARRAY_LENGTH = mPreviewSize.width*mPreviewSize.height*3/2;
                    int argb8888[] = new int[ARRAY_LENGTH];

                    decodeYUV(argb8888, data, mPreviewSize.width, mPreviewSize.height);
                    Bitmap bitmap = Bitmap.createBitmap(argb8888, mPreviewSize.width, mPreviewSize.height, Config.ARGB_8888);

                    FileOutputStream fos;
                    try {
                        fos = new FileOutputStream(String.format("/sdcard/testImage/%d.jpg", System.currentTimeMillis()));


                    BufferedOutputStream bos = new BufferedOutputStream(fos);
                    bitmap.compress(CompressFormat.JPEG, 75, bos);

                    bos.flush();
                    bos.close();
                    fos.close();
                    } catch (FileNotFoundException ex) {
                        Logger.getLogger(Preview.class.getName()).log(Level.SEVERE, null, ex);
                    }
                    catch (IOException ex) {
                            Logger.getLogger(Preview.class.getName()).log(Level.SEVERE, null, ex);
                        }

                }
            };

// decode Y, U, and V values on the YUV 420 buffer described as YCbCr_422_SP by Android 
    // David Manpearl 081201 
    public void decodeYUV(int[] out, byte[] fg, int width, int height)
    throws NullPointerException, IllegalArgumentException {
int sz = width * height;
if (out == null)
    throw new NullPointerException("buffer out is null");
if (out.length < sz)
    throw new IllegalArgumentException("buffer out size " + out.length
            + " < minimum " + sz);
if (fg == null)
    throw new NullPointerException("buffer 'fg' is null");
if (fg.length < sz)
    throw new IllegalArgumentException("buffer fg size " + fg.length
            + " < minimum " + sz * 3 / 2);
int i, j;
int Y, Cr = 0, Cb = 0;
for (j = 0; j < height; j++) {
    int pixPtr = j * width;
    final int jDiv2 = j >> 1;
    for (i = 0; i < width; i++) {
        Y = fg[pixPtr];
        if (Y < 0)
            Y += 255;
        if ((i & 0x1) != 1) {
            final int cOff = sz + jDiv2 * width + (i >> 1) * 2;
            Cb = fg[cOff];
            if (Cb < 0)
                Cb += 127;
            else
                Cb -= 128;
            Cr = fg[cOff + 1];
            if (Cr < 0)
                Cr += 127;
            else
                Cr -= 128;
        }
        int R = Y + Cr + (Cr >> 2) + (Cr >> 3) + (Cr >> 5);
        if (R < 0)
            R = 0;
        else if (R > 255)
            R = 255;
        int G = Y - (Cb >> 2) + (Cb >> 4) + (Cb >> 5) - (Cr >> 1)
                + (Cr >> 3) + (Cr >> 4) + (Cr >> 5);
        if (G < 0)
            G = 0;
        else if (G > 255)
            G = 255;
        int B = Y + Cb + (Cb >> 1) + (Cb >> 2) + (Cb >> 6);
        if (B < 0)
            B = 0;
        else if (B > 255)
            B = 255;
        out[pixPtr++] = 0xff000000 + (B << 16) + (G << 8) + R;
    }
}

    }


public void surfaceDestroyed(SurfaceHolder holder) {
    //mCamera.setPreviewCallback(null);
    if(mCamera != null) {
        mCamera.stopPreview();
    }  
}

private Size getOptimalPreviewSize(List<Size> sizes, int w, int h) {
    final double ASPECT_TOLERANCE = 0.1;
    double targetRatio = (double)w/h;
    if(sizes==null) {
        return null;
    }
    Size optimalSize = null;
    double minDiff = Double.MAX_VALUE;

    int targetHeight = h;

    for(Size size : sizes) {
        double ratio = (double) size.width / size.height;
        if(Math.abs(ratio - targetRatio) > ASPECT_TOLERANCE) continue;
        if(Math.abs(size.height - targetHeight) < minDiff) {
            optimalSize = size;
            minDiff = Math.abs(size.height - targetHeight);
        }
    }

    if(optimalSize == null) {
        minDiff = Double.MAX_VALUE;
        for (Size size : sizes) {
            if(Math.abs(size.height - targetHeight) < minDiff) {
                optimalSize = size;
                minDiff = Math.abs(size.height - targetHeight);
            }

        }
    }
    return optimalSize;
}

public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) {
    Camera.Parameters parameters = mCamera.getParameters();
    parameters.setPreviewSize(mPreviewSize.width, mPreviewSize.height);
    //mCamera.setDisplayOrientation(90);
    requestLayout();
    mCamera.setPreviewCallback(mPreviewCallback);
    mCamera.setParameters(parameters);
    mCamera.startPreview();
    }

public Camera.Size getBestPreviewSize(Camera.Parameters parameters, int w, int h)
{
    Camera.Size result = null; 

    for (Camera.Size size : parameters.getSupportedPreviewSizes())
    {
        if (size.width <= w && size.height <= h)
        {
            if (null == result)
            result = size; 
        else
        {
            int resultDelta = w - result.width + h - result.height;
            int newDelta    = w - size.width   + h - size.height;

                if (newDelta < resultDelta)
            result = size; 
        }
        } 
    }
    return result; 
}
    }

---

你的错误就在上面

requestWindowFeature(Window.FEATURE_NO_TITLE);

通过使标题为空，将活动声明为清单中没有标题要简单得多

看一看，您可能会更好地理解它是如何工作的

---

祝你好运

您得到的错误是由以下行引起的：

requestWindowFeature(Window.FEATURE_NO_TITLE);

必须在调用父方法之后立即调用它。 在您的情况下，您不会因为该顺序而崩溃：

super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
setContentView(R.layout.main);
getWindow().addFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN);
setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);

---

logcat怎么解释它崩溃的原因？你能发布完整的logcat错误输出吗？请详细说明：我的程序崩溃了。发布stacktrace，或者至少是抛出的异常和您发布的代码中的行号。我是android编程新手，可以告诉我logcat在哪里吗？public void onCreateBundle savedInstanceState{super.onCreatesavedInstanceState；//setContentViewR.layout.main；//如果我添加这一行，应用程序将突然启动您的命令提示符。然后在安装SDK/platform tools/adb.exe LogcatHanks的任何地方运行。感谢您的帮助。但我不知道它是如何基于文档工作的。可以给我一些简单的解释吗？在您的AndroidM中声明活动的anifest.xml，将活动标题留空。然后，它将不显示标题。

requestWindowFeature(Window.FEATURE_NO_TITLE);

super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
setContentView(R.layout.main);
getWindow().addFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN);
setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);