How to hide layouts / views programmatically in Android

Question

I have just started learning Android. Few confusions I have regarding layouts in XML

1. Are all views that I define in my layout are essentially inflated or they are optional? Suppose I have two different views in a view-group but I want to use only first or only second conditionally. Is it possible?

2. How dynamically created views deal with layout.XML file?

3. If I want received messages to be shown in red and sent messages in black how can I do that?

Answer 1

You can include views in the XML layout file that are invisible until you programatically display them. Just use "android:visible="gone" or "android:visible="invisible" in the XML file.

For instance, I include the following in my layout file initially but it's not visible:

    <LinearLayout
        android:id="@+id/pnlLatLong"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="vertical"
        android:visibility="gone"
        >
        <TextView
            android:id="@+id/lblLatLng"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/lat_long"
            />
        <EditText
            android:id="@+id/txtLatitude"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:inputType="numberDecimal|numberSigned"
            />
        <EditText
            android:id="@+id/txtLongitude"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:inputType="numberDecimal|numberSigned"
            />
    </LinearLayout>

In Java code, when the code logic dictates it should be visible, I change the visibility programatically to:

    View v = findViewById(R.id.pnlLatLng);
    v.setVisibility(View.VISIBLE);