listview runs successfully, but nothing is display in emulator

listview runs successfully, but nothing is display in emulator

I tried to run a simple listview application using arrays.there is no
error on my program, but nothing is display in the emulator.empty screen
is display.why?
This is my program:
package com.example.lvdb;
import java.util.ArrayList;
import java.util.List;
import android.app.Activity;
import android.app.ListActivity;
import android.os.Bundle;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleCursorAdapter;
public class MainActivity extends ListActivity {
String [] values={"TAXI","FOOD","TICKET BOOKING","HOSPITAL"};
protected void oncreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
ListView lists=getListView();
lists = (ListView) findViewById(R.id.lv);
ArrayAdapter<String> adapter=new
ArrayAdapter<String>(this,android.R.layout.simple_list_item_1,values);
lists.setAdapter(adapter);
}
}