Question

我想制作一个导航抽屉，它是一个侧面菜单（当您向右滑动时会出现），您在其中单击一个按钮，然后弹出另一个菜单，而不是在同一侧面字段中弹出。我在主菜单（为Fragment1）的按钮上使用setOnClickListener（）来弹出第二个菜单（为Fragment2）。代码可以编译，但是应用程序在开始时崩溃。

如何解决？也许还有另一种制作菜单的方法？

override fun onCreate(savedInstanceState: Bundle?)
    {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        loadF1(Frag1())
        button1.setOnClickListener()
        {
            loadF2(Frag2())
        }
    }

修改：

堆栈跟踪

com.example.test0 E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.test0, PID: 4903
    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.test0/com.example.test0.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.Button.setOnClickListener(android.view.View$OnClickListener)' on a null object reference
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2817)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2892)
        at android.app.ActivityThread.-wrap11(Unknown Source:0)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1593)
        at android.os.Handler.dispatchMessage(Handler.java:105)
        at android.os.Looper.loop(Looper.java:164)
        at android.app.ActivityThread.main(ActivityThread.java:6541)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)
     Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.Button.setOnClickListener(android.view.View$OnClickListener)' on a null object reference
        at com.example.test0.MainActivity.onCreate(MainActivity.kt:19)
        at android.app.Activity.performCreate(Activity.java:6975)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1213)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2770)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2892) 
        at android.app.ActivityThread.-wrap11(Unknown Source:0) 
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1593) 
        at android.os.Handler.dispatchMessage(Handler.java:105) 
        at android.os.Looper.loop(Looper.java:164) 
        at android.app.ActivityThread.main(ActivityThread.java:6541) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)

Answer 1

使用这样的组和项目：

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android">

    <group android:checkableBehavior="single">
        <item
            android:id="@+id/nav_home"
            android:icon="@drawable/ic_home_black_24dp"
            android:title="@string/nav_home" />
        <item
            android:id="@+id/nav_photos"
            android:icon="@drawable/ic_photo_library_black_24dp"
            android:title="@string/nav_photos" />
        <item
            android:id="@+id/nav_movies"
            android:icon="@drawable/ic_local_movies_black_24dp"
            android:title="@string/nav_movies" />

        <item
            android:id="@+id/nav_notifications"
            android:icon="@drawable/ic_notifications_black_24dp"
            android:title="@string/nav_notifications" />

        <item
            android:id="@+id/nav_settings"
            android:icon="@drawable/ic_settings_black_24dp"
            android:title="@string/nav_settings" />
    </group>

    <item android:title="Other">
        <menu>
            <item
                android:id="@+id/nav_about_us"
                android:title="@string/nav_about_us" />
            <item
                android:id="@+id/nav_privacy_policy"
                android:title="@string/privacy_policy" />
        </menu>
    </item>

</menu>

并使用diff处理可见性。 xml

看看这个：https://www.androidhive.info/2013/11/android-sliding-menu-using-navigation-drawer/

如何在导航抽屉中制作2个菜单

1 个答案: