按钮功能不起作用 - Android Studio

Question

每次运行代码时，应用程序崩溃它只有在我摆脱按钮点击事件时才有效，所以据我所知，问题出在 Btnclklistner 中事件

//package *******.*********;<<package not important 

import android.app.Activity;
import android.os.Bundle;
//import android.view.Menu;<<i did this because i didnt really need to import them at the moment
//import android.view.MenuItem;<<
import android.view.View;
import android.webkit.WebView;
import android.widget.Button;

public class MyActivity extends Activity {
private WebView myWebview;

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

        myWebview = (WebView) findViewById(R.id.webView);
        myWebview.getSettings().setJavaScriptEnabled(true);
        myWebview.loadUrl("http://clarkstoninfoboard.com/");
        myWebview.getSettings().setLoadWithOverviewMode(true);
        myWebview.getSettings().setUseWideViewPort(true);
        myWebview.getSettings().setBuiltInZoomControls(true);
        myWebview.getSettings().setDisplayZoomControls(false);
       Btnclklistner();

        }
 private void Btnclklistner() {
        Button WebRefresh = (Button) findViewById(R.id.btn_reld);
        WebRefresh.setOnClickListener(new View.OnClickListener() {

         @Override
         public void onClick(View view) {
             myWebview.reload();
         }
        });


    }

例外：

FATAL EXCEPTION: main
Process: kirusoft.clarkstonupdates, PID: 7916 java.lang.RuntimeException: Unable to start activity ComponentInfo{kirusoft.clarkstonupdates/kirusoft.clarkstonupdates.MyActivity}: java.lang.NullPointerException
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2328)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2386)
            at android.app.ActivityThread.access$900(ActivityThread.java:169)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1277)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:136)
            at android.app.ActivityThread.main(ActivityThread.java:5476)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:515)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1268)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1084)
            at dalvik.system.NativeStart.main(Native Method)
     Caused by: java.lang.NullPointerException
            at kirusoft.clarkstonupdates.MyActivity.Btnclklistner(MyActivity.java:31)
            at kirusoft.clarkstonupdates.MyActivity.onCreate(MyActivity.java:26)
            at android.app.Activity.performCreate(Activity.java:5473)
            at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1093)
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2292)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2386)
            at android.app.ActivityThread.access$900(ActivityThread.java:169)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1277)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:136)
            at android.app.ActivityThread.main(ActivityThread.java:5476)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:515)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1268)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1084)
            at dalvik.system.NativeStart.main(Native Method)

布局XML

 <Button
        style="?android:attr/borderlessButtonStyle"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Reload"
        android:textSize="10dp"
        android:textColor="#939393"
        android:id="@+id/btn_reld"
        android:layout_alignParentTop="true"
        android:layout_alignRight="@+id/webView"
        android:layout_alignEnd="@+id/webView"
        android:layout_above="@+id/webView" />