if (getIntent().hasExtra("key")) {

                                if(key.compareTo(App_id)==0)
                                  {
                                    setContentView(R.layout.home);
                                  }

                              }
                              else {

                                     finish();
                                   }

03-20 13:47:30.270: E/AndroidRuntime(1628): FATAL EXCEPTION: main
03-20 13:47:30.270: E/AndroidRuntime(1628): java.lang.RuntimeException: Unable to start     activity ComponentInfo{com.example.test/com.example.meetap.AdHome}:     java.lang.NullPointerException
03-20 13:47:30.270: E/AndroidRuntime(1628):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1955)
03-20 13:47:30.270: E/AndroidRuntime(1628):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1980)
03-20 13:47:30.270: E/AndroidRuntime(1628):     at android.app.ActivityThread.access$600(ActivityThread.java:122)
03-20 13:47:30.270: E/AndroidRuntime(1628):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1146)
03-20 13:47:30.270: E/AndroidRuntime(1628):     at android.os.Handler.dispatchMessage(Handler.java:99)
03-20 13:47:30.270: E/AndroidRuntime(1628):     at android.os.Looper.loop(Looper.java:137)
03-20 13:47:30.270: E/AndroidRuntime(1628):     at android.app.ActivityThread.main(ActivityThread.java:4340)
03-20 13:47:30.270: E/AndroidRuntime(1628):     at java.lang.reflect.Method.invokeNative(Native Method)
03-20 13:47:30.270: E/AndroidRuntime(1628):     at java.lang.reflect.Method.invoke(Method.java:511)
03-20 13:47:30.270: E/AndroidRuntime(1628):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
03-20 13:47:30.270: E/AndroidRuntime(1628):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
03-20 13:47:30.270: E/AndroidRuntime(1628):     at dalvik.system.NativeStart.main(Native Method)
03-20 13:47:30.270: E/AndroidRuntime(1628): Caused by: java.lang.NullPointerException
03-20 13:47:30.270: E/AndroidRuntime(1628):     at com.example.meetap.AdHome.onCreate(AdHome.java:374)
03-20 13:47:30.270: E/AndroidRuntime(1628):     at android.app.Activity.performCreate(Activity.java:4465)
03-20 13:47:30.270: E/AndroidRuntime(1628):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049)
03-20 13:47:30.270: E/AndroidRuntime(1628):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1919)
03-20 13:47:30.270: E/AndroidRuntime(1628):     ... 11 more

Button close=(Button)findViewById(R.id.close);
close.setOnClickListener(new OnClickListener()
{
public void onClick(View v)
{
 finish();
}
});

Button close=(Button)findViewById(R.id.close);
close.setOnClickListener(new OnClickListener()
{
public void onClick(View v)
{
 finish();
}
});

View view = infalter.inflate(R.layout.customlayout,null);
Button close=(Button)view.findViewById(R.id.close);