camera app not working?

You have to unlock the camera before creating MediaRecorder. And lock it before releasing it.

Try this code, it will work Have fun…

package com.marcodinacci.book.acb;

import java.io.IOException;
import android.app.Activity;
import android.content.pm.ActivityInfo;
import android.hardware.Camera;
import android.media.MediaRecorder;
import android.os.Bundle;
import android.view.Surface;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.ToggleButton;

public class MediaRecorderRecipe extends Activity implements SurfaceHolder.Callback {

    private final String VIDEO_PATH_NAME = "/mnt/sdcard/VGA_30fps_512vbrate.mp4";

    private MediaRecorder mMediaRecorder;
    private Camera mCamera;
    private SurfaceView mSurfaceView;
    private SurfaceHolder mHolder;
    private View mToggleButton;
    private boolean mInitSuccesful;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.media_recorder_recipe);

        // we shall take the video in landscape orientation
        setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);

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

        mToggleButton = (ToggleButton) findViewById(R.id.toggleRecordingButton);
        mToggleButton.setOnClickListener(new OnClickListener() {
            @Override
            // toggle video recording
            public void onClick(View v) {
                if (((ToggleButton)v).isChecked()) {
                    mMediaRecorder.start();
                    try {
                        Thread.sleep(10 * 1000);
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                    finish();
                }
                else {
                    mMediaRecorder.stop();
                    mMediaRecorder.reset();
                    try {
                        initRecorder(mHolder.getSurface());
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
            }
        });     
    }

    /* Init the MediaRecorder, the order the methods are called is vital to
     * its correct functioning */
    private void initRecorder(Surface surface) throws IOException {
        // It is very important to unlock the camera before doing setCamera
        // or it will results in a black preview
        if(mCamera == null) {
            mCamera = Camera.open();
            mCamera.unlock();
        }

        if(mMediaRecorder == null)  mMediaRecorder = new MediaRecorder();
        mMediaRecorder.setPreviewDisplay(surface);
        mMediaRecorder.setCamera(mCamera);

        mMediaRecorder.setVideoSource(MediaRecorder.VideoSource.DEFAULT);
       //       mMediaRecorder.setOutputFormat(8);
        mMediaRecorder.setOutputFormat(MediaRecorder.OutputFormat.MPEG_4);
        mMediaRecorder.setVideoEncoder(MediaRecorder.VideoEncoder.H264);
        mMediaRecorder.setVideoEncodingBitRate(512 * 1000);
        mMediaRecorder.setVideoFrameRate(30);
        mMediaRecorder.setVideoSize(640, 480);
        mMediaRecorder.setOutputFile(VIDEO_PATH_NAME);

        try {
            mMediaRecorder.prepare();
        } catch (IllegalStateException e) {
            // This is thrown if the previous calls are not called with the 
            // proper order
            e.printStackTrace();
        }

        mInitSuccesful = true;
    }

    @Override
    public void surfaceCreated(SurfaceHolder holder) {
        try {
            if(!mInitSuccesful)
                initRecorder(mHolder.getSurface());
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    @Override
    public void surfaceDestroyed(SurfaceHolder holder) {
        shutdown();
    }

    @Override
    public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {}

    private void shutdown() {
        // Release MediaRecorder and especially the Camera as it's a shared
        // object that can be used by other applications
        mMediaRecorder.reset();
        mMediaRecorder.release();
        mCamera.release();

        // once the objects have been released they can't be reused
        mMediaRecorder = null;
        mCamera = null;
    }

}

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
      package="com.marcodinacci.book.acb"
      android:versionCode="1"
      android:versionName="1.0">

     <uses-sdk android:minSdkVersion="7" />
     <uses-permission android:name="android.permission.CAMERA"/>
     <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
     <uses-permission android:name="android.permission.RECORD_AUDIO" />
     <uses-feature android:name="android.hardware.camera.autofocus" />

     <application android:icon="@drawable/icon" android:label="@string/app_name">
        <activity android:name="MediaRecorderRecipe"
              android:label="@string/app_name">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

     </application>
</manifest>

media_recorder_recipe.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent">
    <ToggleButton
         android:id="@+id/toggleRecordingButton"
         android:layout_width="fill_parent"
         android:textOff="Start Recording" 
         android:textOn="Stop Recording"
         android:layout_height="wrap_content"/>

    <FrameLayout
        android:layout_width="fill_parent"
        android:layout_height="fill_parent">
        <SurfaceView android:id="@+id/surfaceView" 
            android:layout_width="fill_parent" 
            android:layout_height="fill_parent"></SurfaceView>
    </FrameLayout>

</LinearLayout>