requestWindowFeature(Window.FEATURE_NO_TITLE);引发了异常。

Question

import android.content.pm.ActivityInfo;
import android.os.Bundle;
import android.preference.ListPreference;
import android.preference.Preference;
import android.preference.PreferenceActivity;
import android.util.Log;
import android.view.Window;
import android.view.WindowManager;

public class OptionsActivity extends PreferenceActivity {
 private ListPreference mListPreference;

 @Override
 protected void onCreate (Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);

  setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);
  requestWindowFeature(Window.FEATURE_NO_TITLE);
  getWindow().addFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN);
              getWindow().clearFlags(WindowManager.LayoutParams.FLAG_FORCE_NOT_FULLSCREEN);

  addPreferencesFromResource(R.xml.options);
  mListPreference = (ListPreference) findPreference("listpreference");
  mListPreference.setPersistent(false);  

 }
}

Exception Stacktrace is given below:
01-27 12:35:51.920: ERROR/AndroidRuntime(615): FATAL EXCEPTION: main
01-27 12:35:51.920: ERROR/AndroidRuntime(615): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.android.game/com.android.game.OptionsActivity}: android.util.AndroidRuntimeException: requestFeature() must be called before adding content
01-27 12:35:51.920: ERROR/AndroidRuntime(615):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2663)
01-27 12:35:51.920: ERROR/AndroidRuntime(615):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679)
01-27 12:35:51.920: ERROR/AndroidRuntime(615):     at android.app.ActivityThread.access$2300(ActivityThread.java:125)
01-27 12:35:51.920: ERROR/AndroidRuntime(615):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033)
01-27 12:35:51.920: ERROR/AndroidRuntime(615):     at android.os.Handler.dispatchMessage(Handler.java:99)
01-27 12:35:51.920: ERROR/AndroidRuntime(615):     at android.os.Looper.loop(Looper.java:123)
01-27 12:35:51.920: ERROR/AndroidRuntime(615):     at android.app.ActivityThread.main(ActivityThread.java:4627)
01-27 12:35:51.920: ERROR/AndroidRuntime(615):     at java.lang.reflect.Method.invokeNative(Native Method)
01-27 12:35:51.920: ERROR/AndroidRuntime(615):     at java.lang.reflect.Method.invoke(Method.java:521)
01-27 12:35:51.920: ERROR/AndroidRuntime(615):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
01-27 12:35:51.920: ERROR/AndroidRuntime(615):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
01-27 12:35:51.920: ERROR/AndroidRuntime(615):     at dalvik.system.NativeStart.main(Native Method)
01-27 12:35:51.920: ERROR/AndroidRuntime(615): Caused by: android.util.AndroidRuntimeException: requestFeature() must be called before adding content
01-27 12:35:51.920: ERROR/AndroidRuntime(615):     at com.android.internal.policy.impl.PhoneWindow.requestFeature(PhoneWindow.java:172)
01-27 12:35:51.920: ERROR/AndroidRuntime(615):     at android.app.Activity.requestWindowFeature(Activity.java:2719)
01-27 12:35:51.920: ERROR/AndroidRuntime(615):     at com.android.game.OptionsActivity.onCreate(OptionsActivity.java:20)
01-27 12:35:51.920: ERROR/AndroidRuntime(615):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
01-27 12:35:51.920: ERROR/AndroidRuntime(615):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2627)
01-27 12:35:51.920: ERROR/AndroidRuntime(615):     ... 11 more

- Nuraiz

Answer 1

在添加/清除标志代码之后移动setRequestedOrientation()。

编辑：如下所述，我没有看到它正在使用preferenceActivity。 仅供参考，这是PreferenceActivity.onCreate()，您需要调用super.onCreate():

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    requestWindowFeature(Window.FEATURE_NO_TITLE);

    setContentView(com.android.internal.R.layout.preference_list_content);

    mPreferenceManager = onCreatePreferenceManager();
    getListView().setScrollBarStyle(View.SCROLLBARS_INSIDE_INSET);
}

为什么在super.onCreate()已经请求了该特性，你还要请求FEATURE_NO_TITLE呢？有时如果你深入挖掘Android源代码，会很有帮助。

- Oliver

---

是的，我刚刚看到你扩展了PreferenceActivity。未格式化的文本难以阅读。 通过扩展PreferenceActivity，你无法这样做。一旦调用super.onCreate()方法，ViewGroup将被设置，因此不允许更改Window的参数。你可以尝试在稍后的状态下调用super.onCreate()方法（在窗口标志设置之后），但我怀疑你能否在创建的那个状态下访问Window的成员。 - Oliver

我编辑了我的答案，这样你就可以看到在super.onCreate()上发生了什么。 - Oliver

Answer 2

在这种情况下，super正在设置内容视图，您必须在设置内容视图之前使用requestWindowFeature。因此，在调用super之前使用requestWindowFeature。

public class LandNavSettings extends PreferenceActivity implements
            SharedPreferences.OnSharedPreferenceChangeListener {

    @Override
    protected void onCreate(Bundle icicle) {
            requestWindowFeature(Window.FEATURE_NO_TITLE);
            super.onCreate(icicle);     
    }
}

- Christopher Grabowski