How to start a Camera with an intent in Android?
 
 Procedure
 - Start the Eclipse IDE.
- Create a new project.
- Create a MainActivity.java file.
- Create an activity_main.xml file for the layout design.
- Add a button in the xml layout.
- Then look up the button by its id in the MainActivity.java file.
- In the onClick function, start an activity with an  intent as the MediaStore.
like this
 Intent i=new Intent(MediaStore.ACTION_VIDEO_CAPTURE);
 startActivity(i);
  
 Code is given below
 MainActivity.java
 package com.example.camerawithintent;
 import android.app.Activity;
 import android.content.Intent;
 import android.os.Bundle;
 import android.provider.MediaStore;
 import android.view.Menu;
 import android.view.View;
 import android.view.View.OnClickListener;
 import android.widget.Button;
  
 public class MainActivity extends Activity {
 Button btn;
             @Override
             protected void onCreate(Bundle savedInstanceState) {
                         super.onCreate(savedInstanceState);
                         setContentView(R.layout.activity_main);
                         btn=(Button)findViewById(R.id.button1);
                         btn.setOnClickListener(new OnClickListener() {
                                     
                                     public void onClick(View v) {
                                                 // TODO Auto-generated method  stub
                                                 Intent i=new  Intent(MediaStore.ACTION_VIDEO_CAPTURE);
                                                 startActivity(i);
                                     }
                         });
             }
             @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;
             } 
 }
  
 activity_main.xml
   <RelativeLayout   xmlns:android="http://schemas.android.com/apk/res/android"
         xmlns:tools="http://schemas.android.com/tools"
         android:layout_width="match_parent"
         android:layout_height="match_parent"
         android:paddingBottom="@dimen/activity_vertical_margin"
         android:paddingLeft="@dimen/activity_horizontal_margin"
         android:paddingRight="@dimen/activity_horizontal_margin"
         android:paddingTop="@dimen/activity_vertical_margin"
         tools:context=".MainActivity"  >
      <Button
             android:id="@+id/button1"
             android:layout_width="wrap_content"
             android:layout_height="wrap_content"
             android:layout_alignParentLeft="true"
             android:layout_alignParentTop="true"
             android:layout_marginLeft="81dp"
             android:layout_marginTop="54dp"
             android:text="Button"  />
   </RelativeLayout>
 Output