Android:Navigation DrawerのItemをSpinnerにしたい

お世話になります。

色々と試行錯誤してみましたが、下記のエラーの解消方法がわかりません。
お手数ですが、ご教示のほどよろしくお願い致します。

java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.Spinner.setAdapter(android.widget.SpinnerAdapter)' on a null object reference

実現したいこと

ナビゲーションドロワーのアイテムを一か所スピナーにしたい。

参考元

https://stackoverflow.com/questions/37696653/how-to-add-spinner-as-an-item-in-navigation-drawer/37697483#37697483

実行時エラーログ

E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.test, PID: 12890
    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.test/com.example.test.ui.login.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.Spinner.setAdapter(android.widget.SpinnerAdapter)' on a null object reference
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3430)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3614)
        at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:86)
        at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:108)
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:68)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2199)
        at android.os.Handler.dispatchMessage(Handler.java:112)
        at android.os.Looper.loop(Looper.java:216)
        at android.app.ActivityThread.main(ActivityThread.java:7625)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:524)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:987)
     Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.Spinner.setAdapter(android.widget.SpinnerAdapter)' on a null object reference
        at com.example.test.ui.login.MainActivity.onCreate(MainActivity.java:88)
        at android.app.Activity.performCreate(Activity.java:7458)
        at android.app.Activity.performCreate(Activity.java:7448)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1286)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3409)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3614) 
        at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:86) 
        at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:108) 
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:68) 
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2199) 
        at android.os.Handler.dispatchMessage(Handler.java:112) 
        at android.os.Looper.loop(Looper.java:216) 
        at android.app.ActivityThread.main(ActivityThread.java:7625) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:524) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:987)

ソースコード

MainActivity.java

java
1@Override
2    protected void onCreate(Bundle savedInstanceState) {
3        super.onCreate(savedInstanceState);
4        setContentView(R.layout.activity_main);
5
6        // Navigation Drawer
7        Toolbar toolbar = findViewById(R.id.toolbar);
8        toolbar.setTitle("");
9        setSupportActionBar(toolbar);
10        //toolbar.setBackgroundColor(0);
11
12        drawer = findViewById(R.id.drawer_layout);
13
14        ActionBarDrawerToggle actionBarDrawerToggle =
15                new ActionBarDrawerToggle(
16                        this, drawer, toolbar, R.string.action_sign_in, R.string.action_regist);
17        drawer.addDrawerListener(actionBarDrawerToggle);
18        actionBarDrawerToggle.syncState();
19
20        NavigationView navigationView = findViewById(R.id.nav_view);
21        navigationView.setNavigationItemSelectedListener(this);
22
23        Spinner sp = (Spinner) navigationView.getMenu().findItem(R.id.nav_ccc).getActionView();
24        names = getResources().getStringArray(R.array.labels_array_ccc);
25        sp.setAdapter(new ArrayAdapter<String>(this,R.layout.spinner_dropdown_item,names));
26        sp.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
27            @Override
28            public void onItemSelected(AdapterView<?> adapterView, View view, int i, long l) {
29
30            }
31
32            @Override
33            public void onNothingSelected(AdapterView<?> adapterView) {
34
35            }
36        });
37
38
39        ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(this, drawer, toolbar,
40                R.string.navigation_drawer_open, R.string.navigation_drawer_close);
41        drawer.addDrawerListener(toggle);
42        toggle.syncState();
43
44        getSupportActionBar().setHomeButtonEnabled(true);
45        getSupportActionBar().setDisplayHomeAsUpEnabled(true);
46        getSupportActionBar().setHomeAsUpIndicator(R.drawable.ic_menu_black_24dp);
47
48        // TabLayout
49        OriginalFragmentPagerAdapter adapter = new OriginalFragmentPagerAdapter(getSupportFragmentManager());
50        viewPager = findViewById(R.id.viewPager);
51        viewPager.setOffscreenPageLimit(2);
52        viewPager.setAdapter(adapter);
53        tabLayout = findViewById(R.id.tabLayout);
54        tabLayout.setupWithViewPager(viewPager);
55
56        createTabIcons();
57
58    }

activity_main.xml

//一部抜粋

<com.google.android.material.navigation.NavigationView
        android:id="@+id/nav_view"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_gravity="start"
        android:background="@color/colorWhite"
        app:headerLayout="@layout/nav_header"
        app:menu="@menu/drawer_menu"
        app:theme="@style/AppTheme.drawer_style"/>

drawer_menu.xml

<menu xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    tools:showIn="navigation">

    <group android:checkableBehavior="single">
        <item
            android:id="@+id/nav_aaa"
            android:icon="@drawable/ic_person_black_24dp"
            android:title="@string/drawer_menu_1" />
        <item
            android:id="@+id/nav_bbb"
            android:icon="@drawable/ic_person_black_24dp"
            android:title="@string/drawer_menu_2" />
        <item
            android:id="@+id/nav_ccc"
            android:icon="@drawable/ic_person_black_24dp"
            android:title="@string/drawer_menu_3"
            android:actionLayout="@layout/spinner_ccc"/>
    </group>
</menu>

spinner_ccc.xml

<?xml version="1.0" encoding="utf-8"?>
<Spinner xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/spinner_ccc_drawer"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_gravity="center_vertical"
android:gravity="center_vertical" />

jimbe

2019/11/08 09:43

> at com.example.test.ui.login.MainActivity.onCreate(MainActivity.java:88) この MainActivity.java の 88 行目とはどこでしょうか.

noname1234

2019/11/08 09:55

回答ありがとうございます。下記の箇所になります。 >sp.setAdapter(new ArrayAdapter<String>(this,R.layout.spinner_dropdown_item,names));

jimbe

2019/11/08 10:01

sp の値が null かは確認されていますか?

noname1234

2019/11/08 10:09

確認したところ、nullになっておりました。

行動規範の内容に同意します

回答1件

ベストアンサー

drawer_menu.xml の menu 要素に xmlns:app="http://schemas.android.com/apk/res-auto" を追加し,
android:actionLayout="@layout/spinner_ccc" を app:actionLayout="@layout/spinner_ccc" と
してみてください.

投稿2019/11/08 10:52

jimbe

総合スコア12648