Question

我构建了一个应用程序，该应用程序基本上显示3个不同的片段，底部具有“底部导航”菜单。我想使用包含Google Map的“浮动操作”按钮打开一个新的Activity，但是不幸的是，如果我尝试运行该应用，则会关闭该应用。

我的MainActivity XML文件：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">

<FrameLayout
    android:id="@+id/fragment_container"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_above="@+id/mapbutton">

    <android.support.design.widget.FloatingActionButton
        android:id="@+id/floatingActionButton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:clickable="true"
        app:srcCompat="@drawable/ic_public"
        tools:ignore="VectorDrawableCompat" />
</FrameLayout>

<android.support.design.widget.BottomNavigationView
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_alignParentBottom="true"
    app:menu="@menu/bottom_navigation"
    android:id="@+id/mapbutton"/>

我的Google Maps Activity XML文件：

<fragment xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:map="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/map"
android:name="com.google.android.gms.maps.SupportMapFragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".TourActivity" />

这是我的MainActivity Java文件：

public class MainActivity extends AppCompatActivity {

private FloatingActionButton button;

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

    BottomNavigationView bottomNav = findViewById(R.id.mapbutton);
    bottomNav.setOnNavigationItemSelectedListener(navListener);

    //I added this if statement to keep the selected fragment when rotating the device
    if (savedInstanceState == null) {
        getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container,
                new BlogActivity()).commit();
    }

    button = findViewById(R.id.mapbutton);
    button.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            openTourActivity();
        }
    });
}

public void openTourActivity(){

    Intent intent = new Intent(this, TourActivity.class);
    startActivity(intent);
}

private BottomNavigationView.OnNavigationItemSelectedListener navListener =
        new BottomNavigationView.OnNavigationItemSelectedListener() {
            @Override
            public boolean onNavigationItemSelected(@NonNull MenuItem item) {
                Fragment selectedFragment = null;

                switch (item.getItemId()) {
                    case R.id.nav_blog:
                        selectedFragment = new BlogActivity();
                        break;
                    case R.id.nav_explore:
                        selectedFragment = new ExporeActivity();
                        break;
                    case R.id.nav_user:
                        selectedFragment = new UserActivity();
                        break;
                }

                getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container,
                        selectedFragment).commit();

                return true;
            }
        };
}

这是Google Map活动。 Tbh我什么都没改变。我只是复制并尝试运行它。

public class TourActivity extends FragmentActivity implements OnMapReadyCallback {

private GoogleMap mMap;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_tour);
    // Obtain the SupportMapFragment and get notified when the map is ready to be used.
    SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
            .findFragmentById(R.id.map);
    mapFragment.getMapAsync(this);
}


/**
 * Manipulates the map once available.
 * This callback is triggered when the map is ready to be used.
 * This is where we can add markers or lines, add listeners or move the camera. In this case,
 * we just add a marker near Sydney, Australia.
 * If Google Play services is not installed on the device, the user will be prompted to install
 * it inside the SupportMapFragment. This method will only be triggered once the user has
 * installed Google Play services and returned to the app.
 */
@Override
public void onMapReady(GoogleMap googleMap) {
    mMap = googleMap;

    // Add a marker in Sydney and move the camera
    LatLng sydney = new LatLng(-34, 151);
    mMap.addMarker(new MarkerOptions().position(sydney).title("Marker in Sydney"));
    mMap.moveCamera(CameraUpdateFactory.newLatLng(sydney));
}}

我的Logcat说：

 Caused by: java.lang.ClassCastException: android.support.design.widget.FloatingActionButton cannot be cast to android.support.design.widget.BottomNavigationView

前段时间，我设法构建了类似的东西，并且奏效了，但这次我很挣扎。如果我将“地图活动”设置为启动器活动，则该应用程序启动，但是从“主要活动”开始，反之则需要它。

期待您的帮助和解答。

Answer 1

此行是错误的：

application/json

用您的 BottomNavigationView ID替换BottomNavigationView bottomNav = findViewById(R.id.mapbutton); .... .... button = findViewById(R.id.mapbutton);。

Google地图集成后，我的应用无法打开

1 个答案: