活动在开始时崩溃

Question

当我点击＆＃34;登录＆＃34;我需要你帮助应用程序崩溃按钮，我做错了什么？ （该应用程序应该在webview中打开一个新活动） 谢谢你的回答， 我有2个活动， 主要代码：

public class MainActivity extends Activity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        setContentView(R.layout.activity_main);
        super.onCreate(savedInstanceState);
        LoadPage();
    }
    public Button Btn;
    public void LoadPage(){
        Btn = (Button)findViewById(R.id.LoginBtn);
        Btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent intent = new Intent(MainActivity.this, WebPage.class);
                startActivity(intent);
                final EditText username = (EditText) findViewById(R.id.LoginTx);
                intent.putExtra("Username", username.getText().toString());
                final EditText password = (EditText) findViewById(R.id.PasswordTx);
                intent.putExtra("Password", password.getText().toString());
            }
        });
    }

WebPage活动代码：

public class WebPage extends AppCompatActivity {
static WebView mWebView;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    final String user = getIntent().getExtras().getString("Username");
    final String pwd = getIntent().getExtras().getString("Password");
    setContentView(R.layout.activity_web_page);
    this.requestWindowFeature(Window.FEATURE_NO_TITLE);
    mWebView = (WebView) findViewById(R.id.webView2);
    String url = "http://www.webnotes.cz/";
    mWebView.getSettings().setJavaScriptEnabled(true);
    mWebView.loadUrl(url);
    mWebView.setWebViewClient(new WebViewClient() {
        public void onPageFinished(WebView view, String url) {
            view.loadUrl("javascript:document.getElementById('UID0').value = '" +user+ "';document.getElementById('PASS0').value='" +pwd+ "';javascript:document.getElementById('butLogon').click();");
        }
    });
}

} 在调试中：

E/AndroidRuntime: FATAL EXCEPTION: main
                  Process: com.example.erikstoklasa.test, PID: 13544
                  java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.erikstoklasa.test/com.example.erikstoklasa.test.WebPage}: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String android.os.Bundle.getString(java.lang.String)' on a null object reference
                      at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2626)
                      at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2695)
                      at android.app.ActivityThread.access$800(ActivityThread.java:173)
                      at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1552)
                      at android.os.Handler.dispatchMessage(Handler.java:111)
                      at android.os.Looper.loop(Looper.java:194)
                      at android.app.ActivityThread.main(ActivityThread.java:5787)
                      at java.lang.reflect.Method.invoke(Native Method)
                      at java.lang.reflect.Method.invoke(Method.java:372)
                      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1009)
                      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:804)
                   Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String android.os.Bundle.getString(java.lang.String)' on a null object reference
                      at com.example.erikstoklasa.test.WebPage.onCreate(WebPage.java:16)
                      at android.app.Activity.performCreate(Activity.java:6105)
                      at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1123)
                      at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2579)
                      at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2695) 
                      at android.app.ActivityThread.access$800(ActivityThread.java:173) 
                      at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1552) 
                      at android.os.Handler.dispatchMessage(Handler.java:111) 
                      at android.os.Looper.loop(Looper.java:194) 
                      at android.app.ActivityThread.main(ActivityThread.java:5787) 
                      at java.lang.reflect.Method.invoke(Native Method) 
                      at java.lang.reflect.Method.invoke(Method.java:372) 
                      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1009) 
                      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:804)