Greetings all!

As a an inexperienced Android programmer I need some help. I'm designing this app for a church that needs an Activity that can record prayer requests (similar to making a to-do list). At this point I can type items into a list, but they don't seem to save and come back after closing using the Shared Preferences excerpt from below:

Java Code:
SharedPreferences prayerRequests = getPreferences(Activity.MODE_PRIVATE);
	
	ListView myListViewa = (ListView)findViewById(R.id.myListView);
	
	SharedPreferences.Editor editor = prayerRequests.edit();
	
	editor.putString("prayers", myListViewa.toString());
	
	editor.apply();
The entire class is here:


Java Code:
package com.direction.investor.prayerjournal;

import java.util.ArrayList;



import android.annotation.TargetApi;
import android.app.Activity;
import android.os.Build;
import android.os.Bundle;
import android.view.KeyEvent;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.EditText;
import android.widget.ListView;
import android.widget.TextView;
import android.content.SharedPreferences;
import android.content.SharedPreferences.Editor;



public class prayerRequests extends Activity {

	@TargetApi(Build.VERSION_CODES.GINGERBREAD)
	public void onCreate(Bundle savedInstanceState) 
	{ super.onCreate(savedInstanceState);
	setContentView(R.layout.prayerrequest);
	
	ListView myListView = (ListView)findViewById(R.id.myListView);
	final EditText myEditText = (EditText)findViewById(R.id.myEditText);
	
	final ArrayList<String> prayers = new ArrayList<String> ();
	
	final ArrayAdapter<String> aa;
	
	aa = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, prayers);
	
	myListView.setAdapter(aa);
	
	
	
	SharedPreferences prayerRequests = getPreferences(Activity.MODE_PRIVATE);
	
	ListView myListViewa = (ListView)findViewById(R.id.myListView);
	
	SharedPreferences.Editor editor = prayerRequests.edit();
	
	editor.putString("prayers", myListViewa.toString());
	
	editor.apply();
	
	
	

	
	
	myEditText.setOnKeyListener(new View.OnKeyListener() {
		public boolean onKey(View v, int keyCode, KeyEvent event) {
			if (event.getAction() == KeyEvent.ACTION_DOWN)
				if ((keyCode == KeyEvent.KEYCODE_DPAD_CENTER) ||
						(keyCode == KeyEvent.KEYCODE_ENTER)) {
					
					prayers.add(0, myEditText.getText().toString());
					aa.notifyDataSetChanged();
					myEditText.setText("");
					return true;
					
				}
			return false;
		}
	});
	
	
	}

	
	}