Android: How to create a Dialog without a title?

You can hide the title of a dialog using:

dialog.requestWindowFeature(Window.FEATURE_NO_TITLE);

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Previous version of this answer, which is overcomplicated:

You need to use an AlertDialog. There's a good explanation on the Android Developer's site about custom dialogs.

In very short summary, you do this with code like copied below from the official website. That takes a custom layot file, inflates it, gives it some basic text and icon, then creates it. You'd show it then with alertDialog.show().

AlertDialog.Builder builder;
AlertDialog alertDialog;

Context mContext = getApplicationContext();
LayoutInflater inflater = (LayoutInflater)
        mContext.getSystemService(LAYOUT_INFLATER_SERVICE);
View layout = inflater.inflate(R.layout.custom_dialog,
        (ViewGroup) findViewById(R.id.layout_root));

TextView text = (TextView) layout.findViewById(R.id.text);
text.setText("Hello, this is a custom dialog!");
ImageView image = (ImageView) layout.findViewById(R.id.image);
image.setImageResource(R.drawable.android);

builder = new AlertDialog.Builder(mContext);
builder.setView(layout);
alertDialog = builder.create();

In response to comment:

I assume that TextView with the id nr is in the View you are inflating with View view = inflater..... If so, then you need to change just one bit: instead of dialog.findView... make it view.findView.... Then once you've done that, remember to use dialog.show(), or even builder.show() without bothering to do builder.create().

FEATURE_NO_TITLE works when creating a dialog from scratch, as in:

Dialog dialog = new Dialog(context);
dialog.requestWindowFeature(Window.FEATURE_NO_TITLE);

But it doesn't work when creating an AlertDialog (or using the Builder), because it already disables the title and use a custom one internally.

I have looked at the SDK sources, and I think that it can't be worked around. So to remove the top spacing, the only solution is to create a custom dialog from scratch IMO, by using the Dialog class directly.

Also, one can do that with a style, eg in styles.xml:

<style name="FullHeightDialog" parent="android:style/Theme.Dialog">
   <item name="android:windowNoTitle">true</item>
</style>

And then:

Dialog dialog = new Dialog(context, R.style.FullHeightDialog);