//In for instance onOptionsItemSelected event call
showDialog(MY_ABOUT_DLG_CONSTANT);


//Then override the onCreateDialog event, and check for 
//the int constant that you passed in showDialog.
@Override
protected Dialog onCreateDialog(int id) {
switch (id) {
case MY_ABOUT_DLG_CONSTANT: {
/*
Use the alert dialog builder to create the dialog, and add the string constants "R.string.aboutXXX" in 
"strings.xml". Then also add a dialog.xml layout.
*/
AlertDialog.Builder d = new AlertDialog.Builder(this);
d.setTitle(R.string.aboutTitle);
d.setIcon(android.R.drawable.ic_menu_info_details);
d.setPositiveButton(R.string.aboutHomepage, new OnClickListener() {
	public void onClick(DialogInterface dialog, int which) {
		Uri uri = Uri.parse(getString(R.string.aboutHomepageUrl));
		startActivity(new Intent(Intent.ACTION_VIEW, uri));
	}
});

//Just add additional buttons like the button above but add them 
//using d.setNeutralButton instead of positive button.

d.setNegativeButton(R.string.aboutClose, null);
View v = LayoutInflater.from(this).inflate(R.layout.dialog, null);
TextView text = (TextView) v.findViewById(R.id.dialogText);
text.setText(getString(R.string.aboutText, getVersion()));
d.setView(v);
return d.create();
}
}
}

/******************
dialog.xml layout
********************


<?xml version="1.0" encoding="utf-8"?>
<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
	android:layout_width="fill_parent" android:layout_height="fill_parent"
	android:padding="6dip">
	<TextView android:id="@+id/dialogText" android:layout_width="fill_parent"
		android:layout_height="wrap_content" android:textSize="12sp"
		android:text="Example text." />
</ScrollView>

*******************/

About dialog with scrollable text and webpage button

android

Java