Android：从选定的 NavigationMenu 项调用上下文菜单

Question

对不起我的英语。

我在 Android 中尝试调用上下文菜单时遇到问题。

Android Studio 在浮动小部件中设置了一个侦听器并且有效：

        FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
    registerForContextMenu(fab);
    fab.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
            openContextMenu(fab);
        }
    });

但是当用户按下 NavigationMenu 的一个项目时尝试调用它，我不确定声明的正确方法：

NavigationMenuItemView navigationItemView = (NavigationMenuItemView) findViewById(R.id.nav_call);

然后使用：

openContextMenu(navigationItemView);

我有这个：

    @SuppressWarnings("StatementWithEmptyBody")
@Override
public boolean onNavigationItemSelected(MenuItem item) {
    NavigationMenuItemView navigationItemView = (NavigationMenuItemView) findViewById(R.id.nav_call); //Declare view maybe like this?

    // Handle navigation view item clicks here.
    int id = item.getItemId();

    if (id == R.id.nav_home) {
        //home
    } else if (id == R.id.nav_call) {
        //Here is my problem
        openContextMenu(navigationItemView);

    }

    DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
    drawer.closeDrawer(GravityCompat.START);
    return true;
}

activity_main_drawer.xml

<?xml version="1.0" encoding="utf-8"?>

<group android:checkableBehavior="single">
    <item
        android:id="@+id/nav_home"
        android:icon="@drawable/ic_home_24dp"
        android:title="Home" />
    <item
        android:id="@+id/nav_call"
        android:icon="@drawable/ic_call_24dp"
        android:title="Call" />
</group>

当然，它不起作用，因为当我按下按钮时应用程序会崩溃并给我空指针异常：

日志：

04-18 00:40:45.561 27548-27548/com.android.test01 E/eglCodecCommon: **** ERROR unknown type 0xb8a05080 (glSizeof,80) 04-18 00:40:45.593 27548-27548/com.android.test01 D/AndroidRuntime: Shutting down VM 04-18 00:40:45.593 27548-27548/com.android.test01 W/dalvikvm: threadid=1: thread exiting with uncaught exception (group=0xa4d14b20) 04-18 00:40:45.593 27548-27548/com.android.test01 E/AndroidRuntime: FATAL EXCEPTION: main Process: com.android.test01, PID: 27548 java.lang.NullPointerException at android.app.Activity.openContextMenu(Activity.java:2933) at com.android.test01.MainActivity.onNavigationItemSelected(MainActivity.java:109) at android.support.design.widget.NavigationView.onMenuItemSelected(NavigationView.java:151) at android.support.v7.view.menu.MenuBuilder.dispatchMenuItemSelected(MenuBuilder.java:811) at android.support.v7.view.menu.MenuItemImpl.invoke(MenuItemImpl.java:152) at android.support.v7.view.menu.MenuBuilder.performItemAction(MenuBuilder.java:958) at android.support.design.internal.NavigationMenuPresenter.onClick(NavigationMenuPresenter.java:318) at android.view.View.performClick(View.java:4438) at android.view.View$PerformClick.run(View.java:18422) at android.os.Handler.handleCallback(Handler.java:733) at android.os.Handler.dispatchMessage(Handler.java:95) at android.os.Looper.loop(Looper.java:136) at android.app.ActivityThread.main(ActivityThread.java:5001) at java.lang.reflect.Method.invokeNative(Native Method) at java.lang.reflect.Method.invoke(Method.java:515) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601) at dalvik.system.NativeStart.main(Native Method)

使用导航项调用上下文菜单的正确方法是什么？

感谢阅读！问候。

Answer 1

好的，我认为这是不可能的，正如另一位用户所说，这没有意义。

然后我用了一个子菜单。

我刚刚编辑了菜单 XML 文件：

activity_main_drawer.xml

<?xml version="1.0" encoding="utf-8"?>

<group android:checkableBehavior="single">
    <item
        android:id="@+id/nav_home"
        android:icon="@drawable/ic_home_24dp"
        android:title="Home" />
    <item
        android:id="@+id/nav_call"
        android:icon="@drawable/ic_call_24dp"
        android:title="Call">
        <menu>
            <item
                android:id="@+id/nav_call1"
                android:icon="@drawable/ic_call_24dp"
                android:title="Call to A" />
            <item
                android:id="@+id/nav_call2"
                android:icon="@drawable/ic_call_24dp"
                android:title="Call to B" />
            <item
                android:id="@+id/nav_call3"
                android:icon="@drawable/ic_call_24dp"
                android:title="Call to C" />
        </menu>
        </item>
</group>

并在 Activity.java 文件中进行验证：

    @SuppressWarnings("StatementWithEmptyBody")
@Override
public boolean onNavigationItemSelected(MenuItem item) {
    // Handle navigation view item clicks here.
    int id = item.getItemId();

    if (id == R.id.nav_home) {
        //Home activity
    } else if (id == R.id.nav_call1) {
        //foo CallNumber(1);
    } else if (id == R.id.nav_call2) {
        //foo CallNumber(2);
    } else if (id == R.id.nav_call3) {
        //foo CallNumber(3);
    }

    DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
    drawer.closeDrawer(GravityCompat.START);
    return true;
}

感谢阅读，问候！

Android：从选定的 NavigationMenu 项调用上下文菜单

Android: Call to context menu from NavigationMenu item selected

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