activity as dialog in android

try with following property

    this.setFinishOnTouchOutside(false);

if you haven't already tried it, then this is the way to achieve activity as dialog: in your manifest file, add to your activity the following attribute:

     <activity
        android:name=".MyActivityName"
        android:theme="@android:style/Theme.Dialog" />

Make change in code as per your need.

Thanks

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:background="@android:color/transparent"
        android:orientation="vertical"
        android:paddingBottom="20dp" >
        <RelativeLayout
            android:id="@+id/RlayMain"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:layout_alignParentLeft="true"
            android:layout_marginLeft="20dp"
            android:layout_marginRight="30dp"
            android:layout_marginTop="120dp"
            android:background="#FFFFFF"
            android:padding="10dp" >
            <TextView
                android:id="@+id/txtsignin"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_centerHorizontal="true"
                android:text="SIGN IN"
                android:textColor="#000000"
                android:textSize="25sp" />
            <EditText
                android:id="@+id/edtUserName"
                android:layout_width="fill_parent"
                android:layout_height="wrap_content"
                android:layout_below="@+id/txtsignin"
                android:layout_marginTop="10dp"
                android:layout_toRightOf="@+id/txtuser"
                android:hint="USERNAME" />
            <EditText
                android:id="@+id/edtPassword"
                android:layout_width="fill_parent"
                android:layout_height="wrap_content"
                android:layout_below="@+id/edtUserName"
                android:layout_marginTop="10dp"
                android:hint="PASSWORD"
                android:inputType="textPassword" />
            <Button
                android:id="@+id/btnSignIn"
                android:layout_width="fill_parent"
                android:layout_height="wrap_content"
                android:layout_below="@+id/edtPassword"
                android:layout_marginTop="10dp"
                android:paddingBottom="10dp"
                android:paddingTop="10dp"
                android:text="Sign In" >
            </Button>
            <Button
                android:id="@+id/btnSignUp"
                android:layout_width="fill_parent"
                android:layout_height="wrap_content"
                android:layout_below="@+id/btnSignIn"
                android:layout_marginTop="10dp"
                android:paddingBottom="10dp"
                android:paddingTop="10dp"
                android:text="Sign Up For Free!" >
            </Button>
        </RelativeLayout>
    </RelativeLayout>

For the issue of avoiding closing the activity when clicking outside window from API 11 as mentioned by Vivek use this.setFinishOnTouchOutside(false);

but for prior APIs use this code:

@Override
public boolean onTouchEvent(MotionEvent event) {
    if ( event.getAction() == MotionEvent.ACTION_DOWN &&  isOutOfBounds(this, event)){
        return true;
    }
    return super.onTouchEvent(event);
}

private boolean isOutOfBounds(Activity context, MotionEvent event) {
    final int x = (int) event.getX();
    final int y = (int) event.getY();
    final int slop = ViewConfiguration.get(context).getScaledWindowTouchSlop();
    final View decorView = context.getWindow().getDecorView();
    return (x < -slop) || (y < -slop)
            || (x > (decorView.getWidth()+slop))
            || (y > (decorView.getHeight()+slop));
}