我遇到了一个与Fragment
相关的令人困惑的事件序列。我正在尝试向Activity
添加一个片段,然后调用片段内的一个方法来更新一些文本。但是,我发现该方法在片段的onCreateView()
完成之前被处理,这导致我得到一个空的View
对象,我的方法失败了。以下是Activity
代码:
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_log_entry_details);
fragmentManager = getSupportFragmentManager();
titleBarFragment = new TitleBarVerticalFragment();
fragmentTransaction = fragmentManager.beginTransaction ();
fragmentTransaction.add(R.id.log_entry_title_frame, titleBarFragment);
fragmentTransaction.commit();
titleBarFragment.updateTitleBar("Edit Log Entry", 20, false);
}
看起来很简单。这是TitleBarVerticalFragment类:
public class TitleBarVerticalFragment extends TitleBarFragment {
@Inject SharedVisualElements sharedVisualElements;
View view;
TextView titleLabel;
public TitleBarVerticalFragment() {
// add this line for any class that want to use any of the singleton objects
Injector.INSTANCE.getAppComponent().inject(this);
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
super.onCreateView(inflater, container, savedInstanceState);
Log.d(Constants.TAG, "title fragment onCreateView()");
view = inflater.inflate(R.layout.fragment_title_bar_vertical, container, false);
ImageView logoImage = (ImageView) view.findViewById(R.id.logo_vertical);
titleLabel = (TextView) view.findViewById(R.id.verticalTitleLabel);
titleLabel.setTextColor(sharedVisualElements.secondaryFontColor());
titleLabel.setTypeface(sharedVisualElements.font());
titleLabel.setTextSize(20);
logoImage.setImageDrawable(sharedVisualElements.logoImage());
logoImage.setBackgroundColor(Color.TRANSPARENT);
return view;
}
public void updateTitleBar(String text, int textSize, boolean titleLabelIsHidden) {
Log.d(Constants.TAG, "about to update title bar text");
if (view == null) {
Log.d(Constants.TAG, "vertical title fragment is null");
return;
}
if (titleLabel == null)
titleLabel = (TextView) view.findViewById(R.id.verticalTitleLabel);
if (titleLabel == null) {
Log.d(Constants.TAG, "vertical title label is null");
return;
}
Log.d(Constants.TAG, "updating title text: " + text);
titleLabel.setText(text);
titleLabel.setTextSize(textSize);
}
请注意此 logcat 输出的顺序。请注意
onCreateView()
看起来在 updateTitleBar()
方法之后运行了?这可能是怎么回事?
如何确保在调用片段的任何其他方法之前先运行即将更新标题栏文本
垂直标题片段为空
标题片段 onCreateView()
onCreateView()
?谢谢。
Fragment
内使用constructor
来传递值到Fragment
中。 - K Neeraj Lal