我有一个由 2 个选项卡组成的活动。问题是,当我有这段代码时:
tabHost.setCurrentTab(0);
我收到以下异常:
03-14 01:06:39.520: ERROR/AndroidRuntime(588): java.lang.NullPointerException
03-14 01:06:39.520: ERROR/AndroidRuntime(588): at android.widget.TabHost.dispatchWindowFocusChanged(TabHost.java:295)
03-14 01:06:39.520: ERROR/AndroidRuntime(588): at android.view.ViewGroup.dispatchWindowFocusChanged(ViewGroup.java:661)
03-14 01:06:39.520: ERROR/AndroidRuntime(588): at android.view.ViewGroup.dispatchWindowFocusChanged(ViewGroup.java:661)
03-14 01:06:39.520: ERROR/AndroidRuntime(588): at android.view.ViewGroup.dispatchWindowFocusChanged(ViewGroup.java:661)
03-14 01:06:39.520: ERROR/AndroidRuntime(588): at android.view.ViewGroup.dispatchWindowFocusChanged(ViewGroup.java:661)
03-14 01:06:39.520: ERROR/AndroidRuntime(588): at android.widget.TabHost.dispatchWindowFocusChanged(TabHost.java:295)
03-14 01:06:39.520: ERROR/AndroidRuntime(588): at android.view.ViewGroup.dispatchWindowFocusChanged(ViewGroup.java:661)
03-14 01:06:39.520: ERROR/AndroidRuntime(588): at android.view.ViewGroup.dispatchWindowFocusChanged(ViewGroup.java:661)
03-14 01:06:39.520: ERROR/AndroidRuntime(588): at android.view.ViewRoot.handleMessage(ViewRoot.java:1819)
03-14 01:06:39.520: ERROR/AndroidRuntime(588): at android.os.Handler.dispatchMessage(Handler.java:99)
03-14 01:06:39.520: ERROR/AndroidRuntime(588): at android.os.Looper.loop(Looper.java:123)
03-14 01:06:39.520: ERROR/AndroidRuntime(588): at android.app.ActivityThread.main(ActivityThread.java:4363)
03-14 01:06:39.520: ERROR/AndroidRuntime(588): at java.lang.reflect.Method.invokeNative(Native Method)
03-14 01:06:39.520: ERROR/AndroidRuntime(588): at java.lang.reflect.Method.invoke(Method.java:521)
03-14 01:06:39.520: ERROR/AndroidRuntime(588): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:860)
03-14 01:06:39.520: ERROR/AndroidRuntime(588): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618)
03-14 01:06:39.520: ERROR/AndroidRuntime(588): at dalvik.system.NativeStart.main(Native Method)
但是,如果我将第二个选项卡更改为默认显示(我只有 2 个选项卡),如下所示:
tabHost.setCurrentTab(1);
一切都正确显示,我也可以在选项卡之间切换。这告诉我选项卡以某种方式正确配置,但是,为什么会出现这种行为?