android - 使用 ActionBarCompat 的带有 ProgressBar 的 NullPointerException

Question

我在 support-v7-r18 中使用 ActionBarCompat。当试图显示不确定的进度时，它适用于 Galaxy S3 Android 4.1.2 但不适用于 Galaxy Ace Android 2.3.3。

我不知道为什么。

引发异常的代码:

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    ...
    final ActionBarActivity activity = this;
    content = (WebView) findViewById(R.id.webContent);
    content.setWebViewClient(new WebViewClient() {
        @Override
        public void onPageStarted(WebView view, String url, Bitmap favicon) {
            super.onPageStarted(view, url, favicon);
            activity.setSupportProgressBarIndeterminate(true);   <=== Line 88
            activity.setSupportProgressBarIndeterminateVisibility(true);
        }
    }

异常:

FATAL EXCEPTION: main
    java.lang.NullPointerException
    at  android.support.v7.app.ActionBarActivityDelegateBase.updateProgressBars(ActionBarActivityDelegateBase.java:508)
    at android.support.v7.app.ActionBarActivityDelegateBase.setSupportProgressBarIndeterminate(ActionBarActivityDelegateBase.java:469)
    at android.support.v7.app.ActionBarActivity.setSupportProgressBarIndeterminate(ActionBarActivity.java:282)
    at MyActivity.onPageStarted(MyActivityActivity.java:88)
    at android.webkit.CallbackProxy.handleMessage(CallbackProxy.java:266)
    at android.os.Handler.dispatchMessage(Handler.java:99)
    at android.os.Looper.loop(Looper.java:123)
    at android.app.ActivityThread.main(ActivityThread.java:3687)
    at java.lang.reflect.Method.invokeNative(Native Method)
    at java.lang.reflect.Method.invoke(Method.java:507)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:867)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:625)
    at dalvik.system.NativeStart.main(Native Method)

Answer 1

在调用 setContentView() 之前将 supportRequestWindowFeature(Window.FEATURE_PROGRESS); 或 supportRequestWindowFeature(Window.FEATURE_INDETERMINATE_PROGRESS); 添加到 onCreate() 方法。