Kindly help SwipeRefreshlayout

import android.os.Bundle;
import android.support.v4.widget.SwipeRefreshLayout;
import android.support.v4.widget.SwipeRefreshLayout.OnRefreshListener;

public class MainActivity extends ListActivity {

    /*
     * Some code has been omitted for brevity
     */
  public SwipeRefreshLayout mRefreshLayout;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }

    public OnRefreshListener mOnRefreshListener = new OnRefreshListener() {
        @Override
        public void onRefresh() {
            // Code that refreshes the content in the layout...
          mRefreshLayout=(SwipeRefreshLayout) findViewById(R.id.refreshLayout);
        }
    }; 
}