尝试隐藏和显示操作栏上的菜单项 [英] Trying to hide and show menu items on action bar

问题描述

我浏览了有关堆栈溢出的问题，找不到解决方法.

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;
}

这会将我的菜单项设置为可见(item1和item2). onclick可以正常工作

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);
    }
}

然后将我的isdown布尔值设置为false.在堆栈上，人们说onPrepareOptionsMenu应该在每次单击时触发，但事实并非如此. 我可以在onclick函数上隐藏一个菜单项

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;
    }
}

但是我有多个菜单项需要隐藏，而其他菜单项则需要显示. 我该怎么办?

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

推荐答案

仅更改isDown变量还不够.每次要更改可见性时，都必须调用setVisible()方法.该方法不仅可以设置布尔值，还可以改变布尔值.

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.

将isDown值更改为false后，您需要调用invalidateOptionsMenu()，这将通过再次调用onPrepareOptionsMenu()重新启动菜单.

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

尝试使用以下代码使菜单项不可见:

Try this code for making the menu items unvisible:

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

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