title: Listview not showing?
body: <p>I am trying to display a list of java lessons and created a listview for a button in my main java class in Android Studio but when I try to run and click the button, it opens another window but the listview doesn't show yet it is on the preview pane on Android Studio.</p>
  
  <p>Here is my java class code:</p>
  
  <pre><code>package unitysoftwenteam.mymainuidesign;
  
  import android.support.v7.app.AppCompatActivity;
  import android.os.Bundle;
  import android.widget.ListView;
  import android.widget.ArrayAdapter;
  import java.util.ArrayList;
  import java.util.List;
  
  public class JAVA_ACTIVITY extends AppCompatActivity {
  
  ListView listview;
  List list = new ArrayList();
  ArrayAdapter adapter;
  
  @Override
  protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_java__activity);
  
      listview = (ListView)findViewById(R.id.jtutoriallist);
  
      list.add("About Java");
      list.add("Print Hello Java");
      list.add("Variables");
      list.add("Updating Variables");
      list.add("Displaying the Output");
      list.add("String Variables");
      list.add("String Concatenation");
      list.add("Variable Names");
      list.add("Data Types");
      list.add("Variable Arithmetic");
      list.add("Casting");
      list.add("Control Flow");
      list.add("If Statement");
      list.add("Variable Scope");
      list.add("Else Statement");
      list.add("Else-If");
      list.add("Boolean Expressions");
      list.add("Logical Operators");
      list.add("Nested If Statements");
      list.add("Switch Statement");
  
      adapter = new ArrayAdapter(JAVA_ACTIVITY.this, 
      android.R.layout.simple_list_item_1);
      listview.setAdapter(adapter);
  }
  }
  </code></pre>
  
  <p>This is my XML code:</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
  xmlns:app="http://schemas.android.com/apk/res-auto"
  xmlns:tools="http://schemas.android.com/tools"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  tools:context="unitysoftwenteam.mymainuidesign.JAVA_ACTIVITY"&gt;
  
    &lt;ListView
      android:id="@+id/jtutoriallist"
      android:layout_width="match_parent"
      android:layout_height="match_parent"
      android:layout_alignParentLeft="true"
      android:layout_alignParentStart="true"
      android:layout_alignParentTop="true" /&gt;
  &lt;/RelativeLayout&gt;
  </code></pre>