Java 在弹出窗口中切换NullPointerException

在settings.xml中：

.....
<Switch
    android:id="@+id/flmode"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_below="@+id/textView1"
    android:layout_marginLeft="30dp"
    android:layout_toRightOf="@+id/textView1" />

<Switch
    android:id="@+id/fmode"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_below="@+id/textView2"
    android:layout_marginLeft="30dp"
    android:layout_toRightOf="@+id/textView2"/>
.....

启动错误后：

11-15 09:26:08.302: E/AndroidRuntime(11433): FATAL EXCEPTION: main
11-15 09:26:08.302: E/AndroidRuntime(11433): java.lang.NullPointerException
11-15 09:26:08.302: E/AndroidRuntime(11433):    at com.test.com.MainFirst.showPopup(MainFirst.java:507)
11-15 09:26:08.302: E/AndroidRuntime(11433):    at com.test.com.MainFirst.onClick(MainFirst.java:242)
11-15 09:26:08.302: E/AndroidRuntime(11433):    at android.view.View.performClick(View.java)
11-15 09:26:08.302: E/AndroidRuntime(11433):    at android.view.View$PerformClick.run(View.java)
11-15 09:26:08.302: E/AndroidRuntime(11433):    at android.os.Handler.handleCallback(Handler.java)
11-15 09:26:08.302: E/AndroidRuntime(11433):    at android.os.Handler.dispatchMessage(Handler.java)
11-15 09:26:08.302: E/AndroidRuntime(11433):    at android.os.Looper.loop(Looper.java)
11-15 09:26:08.302: E/AndroidRuntime(11433):    at android.app.ActivityThread.main(ActivityThread.java)
11-15 09:26:08.302: E/AndroidRuntime(11433):    at java.lang.reflect.Method.invokeNative(Native Method)
11-15 09:26:08.302: E/AndroidRuntime(11433):    at java.lang.reflect.Method.invoke(Method.java:511)
11-15 09:26:08.302: E/AndroidRuntime(11433):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java)
11-15 09:26:08.302: E/AndroidRuntime(11433):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java)
11-15 09:26:08.302: E/AndroidRuntime(11433):    at dalvik.system.NativeStart.main(Native Method)

出了什么问题以及如何实施？ 提前感谢

您需要做什么

Switch flmode = (Switch) popupView.findViewById(R.id.flmode);
Switch fmode = (Switch) popupView.findViewById(R.id.fmode);

代替

Switch flmode = (Switch) findViewById(R.id.flmode);
Switch fmode = (Switch) findViewById(R.id.fmode);    

Switch flmode = (Switch) findViewById(R.id.flmode);
Switch fmode = (Switch) findViewById(R.id.fmode);