Trying to hide and show menu items on action bar

问题:

I have looked through the questions on stack overflow and can't find the solution.

@Override
public boolean onPrepareOptionsMenu(Menu menu) {
    MenuInflater inflater = getMenuInflater();
    inflater.inflate(R.menu.themenu, menu);
    MenuItem   item = menu.findItem(R.id.menu_settings);
    MenuItem item2 = menu.findItem(R.id.menu_save);
    item.setVisible(isdown);
    item2.setVisible(isdown);
    return true;
}

This sets my menu items to visible (item1 and item2). the onclick works fine

public void inflateTextarea() {
    if(isdown == true) {
        isdown = false;
        LinearLayout tl = (LinearLayout)findViewById(R.id.content);
        tl.setVisibility(View.VISIBLE);
        ScaleAnimation scale =  new ScaleAnimation(1, 1, 0, 1);
        scale.setFillAfter(true);
        scale.setDuration(500);
        tl.startAnimation(scale);
    }
}

Then this sets my isdown boolean to false. on stack people say that the onPrepareOptionsMenu should fire everytime I click but this is not the case. I am able to hide one menu item on the onclick function

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    switch(item.getItemId()) {
        case R.id.menu_settings: 
            Log.v("Log:","edit_item pressed");
            return true;
    }
}

But I have multiple menu items that I need to hide and others that I want to show. how can I go about this?

回答1:

Its not enough to change the isDown variable. You have to call the setVisible() method every time you want to change the visibility. That method does more than just setting a boolean value, so just changing a boolean value will not do.

After changing the isDown value to false, you need to call invalidateOptionsMenu() which will re-launch the menu by calling onPrepareOptionsMenu() again.

Try this code for making the menu items unvisible:

...
isdown = false;
invalidateOptionsMenu();
...

回答2:

Try this,

private Menu menu=null;
@Override
public void onCreateOptionsMenu(Menu menu,MenuInflater inflater)
{
    inflater.inflate(R.menu.note_menu, menu);
    this.menu=menu;
super.onCreateOptionsMenu(menu,inflater);
menu.findItem(R.id.menuChartNoteEdit).setVisible(isdown);
menu.findItem(R.id.menuChartOpenNote).setVisible(isdown);
}

When you want to hide menu at any where, after executing onCreateOptionsMenu() then just change value for isdown and repeat this code,

menu.findItem(R.id.menu_settings).setVisible(isdown);
menu.findItem(R.id.menu_save).setVisible(isdown);

回答3:

Try this in your FragmentActivity

public boolean onPreparePanel(int featureId, View view, Menu menu) {
    if(isLeftMenuOpened()) return false;
    return super.onPreparePanel(featureId, view, menu);
}

Method FragmentActivity.onPreparePanel creates menu for all attached fragments. You must return true for the menu to be displayed; if you return false it will not be shown.

回答4:

I have a menu with two items, first: save item, second: edit item. I wanted when I came in to edit, at first "save item" had been hidden, and when I click "edit item", "save item" was shown.

So:

1. declare an item in public
2. set value to it in onCreateOptionsMenu(Menu menu, MenuInflater inflater)
3. set visibility to isHidden()
4. then every where I wanted, set visibility to isVisible()

Public region:

MenuItem saveItem;

onCreateOptionsMenu:

@Override
public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
    inflater.inflate(R.menu.menu_detail_products, menu);
    saveItem = (MenuItem) menu.findItem(R.id.action_detail_product_save);
    saveItem.setVisible(isHidden());
}

Where i want:

saveItem.setVisible(isVisible());

Finally it works as I wanted.