invalidateOptionsMenu不片段工作 [英] invalidateOptionsMenu doesn't work in fragment

问题描述

我要显示或根据动作条隐藏的项目要么他们是在编辑文字的文本或不

I want to show or hide item in actionbar according to either their is text in the edit text or not

所以我做了以下

            public class NounSearch extends  android.app.Fragment 
{

EditText seachEditText;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState)
    {
            super.onCreate(savedInstanceState);
            View rootView = inflater.inflate(R.layout.nounsearchactivity, container, false);
                    //Intiate EditText
            seachEditText =(EditText) rootView.findViewById(R.id.nounSearch);
            seachEditText.setOnEditorActionListener(new TextView.OnEditorActionListener() {
                @Override
                public boolean onEditorAction(TextView v, int actionId, KeyEvent event) {
                    if (actionId == EditorInfo.IME_ACTION_SEARCH) {
                        searchResult.Entities = new ArrayList<NounModel>();
                        _currentPage = 0;
                        categoryId = -1;
                        new GetNouns().execute();
                        return true;
                    }


                    return false;
                }
            });
            seachEditText.addTextChangedListener(new TextWatcher() {

               public void afterTextChanged(Editable s) {
               }

               public void beforeTextChanged(CharSequence s, int start,
                 int count, int after) {
               }

               public void onTextChanged(CharSequence s, int start,
                 int before, int count) {
                 getActivity().invalidateOptionsMenu();
               }
              });

    }
    @Override
    public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
        super.onCreateOptionsMenu(menu, inflater);

            if(seachEditText.getText().toString().length() > 0)
            {
                menu.findItem(R.id.action_search).setVisible(true);
            }
            else
            {
                menu.findItem(R.id.action_search).setVisible(false);
            }
    }





}

但actionitem不会出现

but the actionitem never appear

推荐答案

有关更新 onCreateOptionsMenu 你需要调用该片段中的 setHasOptionsMenu（真）; invalidateOptionsMenu（）里面没有它的片段的onCreate方法您将无法当你调用 getActivity（）来更新它。

For updating the onCreateOptionsMenu inside the fragment you need to call the setHasOptionsMenu(true); inside the onCreate method of the fragment without it you wont be able to update it when you call getActivity().invalidateOptionsMenu();

示例：

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setHasOptionsMenu(true);
}

编辑：

@Override
public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
        if(seachEditText.getText().toString().length() > 0)
        {
            menu.findItem(R.id.action_search).setVisible(true);
        }
        else
        {
            menu.findItem(R.id.action_search).setVisible(false);
        }
    super.onCreateOptionsMenu(menu, inflater);


}

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