activity_main.xml

<!-- Linear layout start here -->
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:background="@drawable/green_back"
    android:fadingEdge="horizontal"
    android:orientation="vertical" >

    <!-- Text view for BMI Text -->

    <!-- Textview for calculator text -->
    <TextView
        android:id="@+id/tv1"
        android:layout_width="286dp"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:paddingLeft="15dp"
        android:paddingTop="40dp"
        android:shadowColor="@android:color/black"
        android:shadowDx="4"
        android:shadowDy="4"
        android:textAlignment="center"
        android:text="Body Mass Index"
        android:textAppearance="?android:attr/textAppearanceLarge"
        android:textColor="@android:color/holo_blue_dark"
        android:textSize="50sp"
        android:typeface="serif" />

    <TextView
        android:id="@+id/tv2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:text="Calculator"
        android:textColor="@android:color/black"
        android:textSize="20dp"
        android:textStyle="bold" />

    <!-- Textview for WEIGHT(KG) text -->
    <TextView
        android:id="@+id/tv3"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:paddingTop="30dp"
        android:text="WEIGHT (KG)"
        android:textAppearance="?android:attr/textAppearanceMedium"
        android:textColor="@android:color/black"
        android:textStyle="bold|italic"
        android:typeface="serif" />

    <!-- Edit text for entering weight with hint in kgs -->
    <EditText
        android:id="@+id/et1"
        android:layout_width="96dp"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:hint="IN KGs"
        android:ems="10"
        android:fadingEdgeLength="10dp"
        android:inputType="numberDecimal"
        android:textAlignment="center" >
        <requestFocus />
    </EditText>

    <!-- Text view for HEIGHT(CM)text -->
    <TextView
        android:id="@+id/tv3"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:paddingTop="30dp"
        android:text="HEIGHT (CM)"
        android:textAppearance="?android:attr/textAppearanceMedium"
        android:textColor="@android:color/black"
        android:textStyle="bold|italic"
        android:typeface="serif"
        tools:ignore="DuplicateIds" />

    <!-- Edit text for entering height with hint in cm -->
    <EditText
        android:id="@+id/et2"
        android:layout_width="96dp"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:hint="IN CMs"
        android:ems="10"
        android:inputType="numberDecimal" >
    </EditText>

    <!-- Button for calculating the formula, when pressed, with calculate written over it -->
    <Button
        android:id="@+id/ib1"
        android:layout_width="158dp"
        android:layout_height="51dp"
        android:layout_gravity="center"
        android:layout_marginTop="20dp"
        android:fadingEdge="vertical"
        android:longClickable="true"
        android:nextFocusRight="@color/black"
        android:text="Calculate"
        android:visibility="visible" />

    <!-- Text view for showing result -->
    <TextView
        android:id="@+id/tv4"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:paddingTop="20dp"
        android:text=""
        android:textSize="20dp"
        android:textStyle="bold"
        android:textColor="@android:color/black"/>

</LinearLayout>
    <!-- Linear layout ends here -->