隐藏 ActionBar 图标

Question

我试图在显示抽屉导航时隐藏图标。这是只隐藏设置，而不是我想要的图标。

在我的 MainActivity 上，我看到如果我添加这段代码图标会隐藏，但是如果我按下其他片段来显示它就会崩溃。

    @Override
public boolean onPrepareOptionsMenu(Menu menu) {
    // if nav drawer is opened, hide the action items
    boolean drawerOpen = mDrawerLayout.isDrawerOpen(mDrawerList);
    menu.findItem(R.id.action_settings).setVisible(!drawerOpen);
    menu.findItem(R.id.ofertasRefresh).setVisible(!drawerOpen); <--- I want to hide this icon
    return super.onPrepareOptionsMenu(menu);
}

当我按下其他片段以显示它时说...：

01-09 20:03:01.493  25761-25761/info.androidhive.slidingmenu E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: info.androidhive.slidingmenu, PID: 25761
java.lang.NullPointerException
        at info.androidhive.slidingmenu.MainActivity.onPrepareOptionsMenu(MainActivity.java:170)
        at android.app.Activity.onPreparePanel(Activity.java:2564)
        at com.android.internal.policy.impl.PhoneWindow.preparePanel(PhoneWindow.java:464)
        at com.android.internal.policy.impl.PhoneWindow.doInvalidatePanelMenu(PhoneWindow.java:800)
        at com.android.internal.policy.impl.PhoneWindow.run(PhoneWindow.java:221)
        at android.view.Choreographer$CallbackRecord.run(Choreographer.java:761)
        at android.view.Choreographer.doCallbacks(Choreographer.java:574)
        at android.view.Choreographer.doFrame(Choreographer.java:543)
        at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:747)
        at android.os.Handler.handleCallback(Handler.java:733)
        at android.os.Handler.dispatchMessage(Handler.java:95)
        at android.os.Looper.loop(Looper.java:136)
        at android.app.ActivityThread.main(ActivityThread.java:5102)
        at java.lang.reflect.Method.invokeNative(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:515)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
        at dalvik.system.NativeStart.main(Native Method)

有什么简单的方法吗？顺便说一句，在我的片段 1 上，我添加了一个 onCreateOptionsMenu 来显示图像并且效果很好。

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

R.menu.refresh_menu.xml

<menu xmlns:android="http://schemas.android.com/apk/res/android">
<item android:id="@+id/ofertasRefresh"
    android:icon="@drawable/ic_action_refresh"
    android:title="Refresh"
    android:alphabeticShortcut="r"
    android:orderInCategory="200"
    android:showAsAction="ifRoom" />
</menu>

干杯。

Answer 1

我认为最好为每个片段和 activity 提供一个菜单 XML。这意味着您不必 hide/show 某些项目。还有关于回调（from the docs）：

The fragment also receives callbacks to onOptionsItemSelected() when a menu item is selected.

Note: Although your fragment receives an on-item-selected callback for each menu item it adds, the activity is first to receive the respective callback when the user selects a menu item. If the activity's implementation of the on-item-selected callback does not handle the selected item, then the event is passed to the fragment's callback. This is true for the Options Menu and context menus.

Answer 2

我认为最好的方法是覆盖 ActionBarDrawerToggle 中的 onDrawerClosed() / onDrawerOpened() 方法。看这里：

public boolean mDrawerOpened;

    ActionBarDrawerToggle abdt = new ActionBarDrawerToggle( ... ) {

        public void onDrawerClosed(View v) {
            super.onDrawerClosed(v);
            mDrawerOpened = false;
            invalidateOptionsMenu();
            syncState();
        }

        public void onDrawerOpened(View v) {
            super.onDrawerClosed(v);
            mDrawerOpened = true;
            invalidateOptionsMenu();
            syncState();
        }

invalidateOptionsMenu() 开始调用主机 Activity 中的 onPrepareOptionsMenu() 方法。那么：

public boolean onPrepareOptionsMenu(Menu menu) {
    if (mDrawerOpened) { menu.removeItem(R.id.ofertasRefresh); }
    if (!mDrawerOpened) { menu.add(Menu.NONE, R.id.ofertasRefresh, Menu.NONE, R.string.title); }
    return super.onPrepareOptionsMenu(menu);
}

使用可见性（可能效果更好）：

public MenuItem mi;

public boolean onPrepareOptionsMenu(Menu menu) {
    if (mi == null) { mi = menu.findItem(R.id.ofertasRefresh); }
    if (mDrawerOpened) { mi.setVisible(false); }
    if (!mDrawerOpened) { mi.setVisible(true); }
    return super.onPrepareOptionsMenu(menu);
}

隐藏 ActionBar 图标

Hide ActionBar icon

java

android

android-fragments