problems with ListViews (Android Studio)

I have two problems in making a ListView in Android studio, first of all, I have a layout in which I want to make a ListView with around 100 elements that I can click on and take me to another layout.

1. This is the content of my layout:

<?xml version="1.0" encoding="utf-8"?>

<RelativeLayout
    xmlns:android="http://ift.tt/nIICcg"
    xmlns:tools="http://ift.tt/LrGmb4"
    android:layout_width="match_parent" android:layout_height="match_parent"
    android:background="#ffff7e00">


    <ListView
        android:id="@android:id/list"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:numColumns="2"
        tools:listitem="@android:layout/simple_list_item_2" />

</RelativeLayout>

In my Preview, next to the XML code, a list of default elements appear, but when I test it in the emulator, is not there, why?

2. I don't know how to edit the ListView in the java file, and how to set the number of elements I want there to be, and how to make them lead me to a respective layout.