我使用stackoverflow和google.I需要计算我的相机和指定对象之间的距离.

为此,我需要找到我的相机的焦距.我也创建了示例项目,但它创建了Null Pointer Exception.请帮助..

代码如下.

public class MainActivity extends Activity {

Camera mcamera;

int focul_length;

Parameters params;

File mFile;

public int PICTURE_ACTIVITY_CODE = 1;

public String FILENAME = "sdcard/photo.jpg";

Camera.Parameters cameraParameters;

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

launchTakePhoto();

}

private void launchTakePhoto()

{

Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);

cameraParameters = mcamera.getParameters();

CameraInfo myinfo = new CameraInfo();

float l=cameraParameters.getFocalLength(); // Here its creating Null Pointer Exception

mFile = new File(FILENAME);

System.out.println("My Focul Length:--"+l);

Uri outputFileUri = Uri.fromFile(mFile);

intent.putExtra(MediaStore.EXTRA_OUTPUT, outputFileUri);

startActivityForResult(intent, PICTURE_ACTIVITY_CODE);

}

Also If possible please provide the code to get angle of Elevation.If possible.I need this very badly.I need your help guys!!

@Override

protected void onActivityResult(int requestCode, int resultCode, Intent data)

{

if (requestCode == PICTURE_ACTIVITY_CODE)

{

if (resultCode == RESULT_OK)

{

ImageView myimageView = (ImageView) findViewById(R.id.imageView1);

Uri inputFileUri = Uri.fromFile(mFile);

myimageView.setImageURI(inputFileUri);

}

}

}

@Override

public boolean onCreateOptionsMenu(Menu menu) {

// Inflate the menu; this adds items to the action bar if it is present.

getMenuInflater().inflate(R.menu.main, menu);

return true;

}

}