Button OnClickListener question inside Android ScrollView

public class MainActivity extends AppCompatActivity implements View.OnClickListener{

    private WebView mWebView;
    private EditText searchBox;

    private Button naver;
    private Button daum;
    private Button google;
    private Button namuwiki;
    private Button naver_endic;
    private ImageButton mic;

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

        naver = (Button) findViewById(btn_naver);
        daum = (Button) findViewById(R.id.btn_daum);
        google = (Button) findViewById(R.id.btn_google);
        namuwiki = (Button) findViewById(R.id.btn_namuwiki);
        naver_endic = (Button) findViewById(R.id.btn_naver_endic);
        mic = (ImageButton) findViewById(R.id.btn_mic);

        searchBox = (EditText) findViewById(R.id.searchBox);

        mWebView = (WebView) findViewById(R.id.webview_content);
        mWebView.getSettings().setJavaScriptEnabled(true);
        mWebView.setWebViewClient(new WebViewClient());
        mWebView.loadUrl("http://www.taila.tk/aiosearch/");
    }

    @Override
    public void onClick(View v) {
        switch (v.getId()) {
            case R.id.btn_naver:
                mWebView.loadUrl("http://www.naver.com");
                Toast.makeText (MainActivity.this, "Naver", Toast.LENGTH_SHORT).show();
                break;
            case R.id.btn_daum:
                Toast.makeText (MainActivity.this, "Next", Toast.LENGTH_SHORT).show();
                break;
            case R.id.btn_google:
                Toast.makeText (MainActivity.this, "Google", Toast.LENGTH_SHORT).show();
                break;
            case R.id.btn_namuwiki:
                Toast.makeText (MainActivity.this, "Treewiki", Toast.LENGTH_SHORT).show();
                break;
            case R.id.btn_naver_endic:
                Toast.makeText (MainActivity.this, "Naver English Dictionary", Toast.LENGTH_SHORT).show();
                break;
        }
    }
}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="10dp"
    tools:context="tk.taila.aiosearch.MainActivity">

    <LinearLayout
        android:orientation="vertical"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="@drawable/border"
        android:layout_marginBottom="8dp"
        android:padding="4dp" >

        <HorizontalScrollView
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:scrollbars="none"
            android:layout_weight="1">

            <LinearLayout
                android:layout_width="wrap_content"
                android:layout_height="match_parent"
                android:orientation="horizontal" >

                <Button
                    android:text="N"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:id="@+id/btn_naver"
                    android:layout_weight="1" />

                <Button
                    android:text="D"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:id="@+id/btn_daum"
                    android:layout_weight="1" />

                <Button
                    android:text="G"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:id="@+id/btn_google"
                    android:layout_weight="1" />

                <Button
                    android:text="NW"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:id="@+id/btn_namuwiki"
                    android:layout_weight="1" />

                <Button
                    android:text="NE"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:id="@+id/btn_naver_endic"
                    android:layout_weight="1" />
            </LinearLayout>

        </HorizontalScrollView>

    </LinearLayout>


</LinearLayout>