Android RecyclerViewer抛出异常

Question

我在我的android项目中使用Volley Library，我一直在努力使用这段代码。如果可以的话，有没有人能够体验到这一点。

logcat的

java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.grafiq.testviewapp/com.example.grafiq.testviewapp.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.v7.widget.RecyclerView.setHasFixedSize(boolean)' on a null object reference
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2694)

MainActivity.java onCreate

   protected void onCreate(Bundle savedInstanceState) {

    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    openActivity = (Button)findViewById(R.id.btn_Child);
    myrecyclerView = (RecyclerView)findViewById(R.id.myRecycleView);
    myrecyclerView.setLayoutManager(new LinearLayoutManager(this));


    //Request Que
    RequestQueue myRequest = VolleySingleton.getInstance().getRequestQue();

    //JsonObjectRequest
    JsonObjectRequest myJsonReq = new JsonObjectRequest(Request.Method.GET, myUrl, null, new Response.Listener<JSONObject>(){

        @Override
        public void onResponse(JSONObject jsonObject) {
            Toast.makeText(MainActivity.this, "JSON-RESPONSE "+jsonObject.toString() ,Toast.LENGTH_LONG).show();
             adapter = new MyAdapter(MainActivity.this, popArray(jsonObject));
            myrecyclerView.setAdapter(adapter);
        }
    }, new Response.ErrorListener(){

        @Override
        public void onErrorResponse(VolleyError volleyError) {
            Toast.makeText(MainActivity.this, "RESPONSE "+volleyError.getMessage() ,Toast.LENGTH_LONG).show();
        }
    });

    myRequest.add(myJsonReq);


}