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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？

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1 回答 1

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我意识到我做错了什么：Tab 机制工作正常，它是为导致 NPE 的第一个选项卡实现的 ListActivity。

于 2011-03-15T21:18:09.477 回答