Java 如何在地图片段中显示地图

导航活动

package com.example.sanad;

import android.os.Bundle;

import androidx.appcompat.app.AppCompatActivity;
import androidx.navigation.NavController;
import androidx.navigation.Navigation;
import androidx.navigation.ui.NavigationUI;

import com.google.android.material.bottomnavigation.BottomNavigationView;

public class navigation extends AppCompatActivity {

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

        BottomNavigationView bottomNavigationView = findViewById(R.id.bottomView);

        NavController navController = Navigation.findNavController(this,R.id.nav_host_fragment);

        NavigationUI.setupWithNavController(bottomNavigationView,navController);


       // Fragment fragment = new MapsFragment();

            //  getSupportFragmentManager().beginTransaction().replace(R.id.map,fragment).commit();
    }
}

地图片段

package com.example.sanad;

import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.fragment.app.Fragment;

import com.google.android.gms.maps.CameraUpdateFactory;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.OnMapReadyCallback;
import com.google.android.gms.maps.SupportMapFragment;
import com.google.android.gms.maps.model.LatLng;
import com.google.android.gms.maps.model.MarkerOptions;

public class MapsFragment extends Fragment {

    private OnMapReadyCallback callback = new OnMapReadyCallback() {

        /**
         * 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) {
            LatLng sydney = new LatLng(-34, 151);
            googleMap.addMarker(new MarkerOptions().position(sydney).title("Marker in Sydney"));
            googleMap.moveCamera(CameraUpdateFactory.newLatLng(sydney));
        }
    };

    @Nullable
    @Override
    public View onCreateView(@NonNull LayoutInflater inflater,
                             @Nullable ViewGroup container,
                             @Nullable Bundle savedInstanceState) {
        return inflater.inflate(R.layout.fragment_maps, container, false);


    }
/** -------------------------------------------------------------*/
    @Override
    public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);
        SupportMapFragment mapFragment =
                (SupportMapFragment) getChildFragmentManager().findFragmentById(R.id.map);
        if (mapFragment != null) {
            mapFragment.getMapAsync(callback);
        }
    }
}
/** ----------------------------------------------------------*/

碎片地图布局

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/map_view"
    android:name="com.google.android.gms.maps.SupportMapFragment"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MapsFragment"
    tools:ignore="DuplicateIds">

    <com.google.android.gms.maps.MapView
        android:id="@+id/map"
        android:layout_width="match_parent"
        android:layout_height="match_parent">

    </com.google.android.gms.maps.MapView>

</RelativeLayout>

导航布局

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout 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=".navigation">

    <com.google.android.material.bottomnavigation.BottomNavigationView
        android:id="@+id/bottomView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        app:menu="@menu/menu_bottom_nav"
        android:background="@color/white_200"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent" />

    <fragment
        android:id="@+id/nav_host_fragment"
        android:name="androidx.navigation.fragment.NavHostFragment"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:defaultNavHost="true"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:navGraph="@navigation/navigation_graphe" />
</androidx.constraintlayout.widget.ConstraintLayout>

您好，我是android开发的新手，我正在尝试创建一个底部导航栏，可以访问3个项目（声明、profile和地图） 我已经设法在登录后显示导航活动，带有3个片段的map声明和profil，但是对于map片段我不能显示map。

---

非常感谢您提供的任何帮助或提示。

我添加了以下代码：

<fragment
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:name="com.google.android.gms.maps.SupportMapFragment"
    tools:context=".MapsActivity">


</fragment>

而不是

<com.google.android.gms.maps.MapView
        android:id="@+id/map"
        android:layout_width="match_parent"
        android:layout_height="match_parent">

    </com.google.android.gms.maps.MapView>

现在地图显示出来了