@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    android.support.v7.widget.Toolbar toolbar = findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);

    NavigationView navigationView = findViewById(R.id.nav_view);
    navigationView.setNavigationItemSelectedListener(this);

    Spinner dropDown = (Spinner) findViewById(R.id.userPAL);
    ArrayAdapter<String> Adapter = new ArrayAdapter<String>(MainActivity.this,
            android.R.layout.simple_list_item_1, getResources().getStringArray(R.array.PALm));
    Adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
    dropDown.setAdapter(Adapter);

<Spinner
    android:id="@+id/userPAL"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_marginLeft="110dp"
    android:layout_marginTop="180dp"
    android:layout_marginRight="130dp">
</Spinner>

<string-array name="PALm">
    <item>Wahl1</item>
    <item>Wahl2</item>
    <item>Wahl3</item>
    <item>Wahl4</item>
    <item>Wahl5</item>
</string-array>