问ArrayAdapter没有更新

EN

package com.niranjanbajgai.test;

import android.app.Activity;
import android.os.Bundle;
import android.view.KeyEvent;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.EditText;
import android.widget.ListView;


import java.util.ArrayList;


public class test extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_test);

        //Get reference to UI widget.
        final ListView myListView = (ListView) findViewById(R.id.myListView);
        final EditText myEditText = (EditText) findViewById(R.id.myEditText);

        //Create the array list
        final ArrayList<String> myArrayList = new ArrayList<String>();

        //create an array adapter to bind array to the list view

        final ArrayAdapter<String> myArrayAdapter = new ArrayAdapter<String>(
                this, android.R.layout.simple_list_item_1, myArrayList);

        myListView.setAdapter(myArrayAdapter);

        myEditText.setOnKeyListener(new View.OnKeyListener() {
            @Override
            public boolean onKey(View view, int keyCode, KeyEvent keyEvent) {
                if(keyEvent.getAction() == keyEvent.ACTION_DOWN){
                    if(keyCode == keyEvent.KEYCODE_ENTER){
                        myArrayList.add(0, myEditText.getText().toString());

                        myArrayAdapter.notifyDataSetChanged();
                        myEditText.setText("");
                    }
                    return true;

                }
                return false;
            }
        });

    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.test, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }
}

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".test">

    <EditText
        android:id="@+id/myEditText"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="@string/addItemHint"/>
    <ListView
        android:id="@+id/myListView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"/>
</LinearLayout>