我希望我的 MainActivity.java 有一个按钮，点击该按钮时应该执行用 MapsActivity.java 编写的代码

Posted 2023-05-06

【中文标题】我希望我的 MainActivity.java 有一个按钮，点击该按钮时应该执行用 MapsActivity.java 编写的代码

【英文标题】：I want my MainActivity.java to have a button which when tapped should execute the code written in MapsActivity.java

【发布时间】：2021-02-02 06:30:58

【问题描述】：

我创建了一个 MapsActivity 和相应的 activity_maps.xml。我的 activity_main.xml 将有一个按钮，当点击该按钮时应显示标记指向的当前位置。

在 androidManifest.xml 中将 MapsActivity 作为 Launcher Activity 时代码工作正常，但希望我的 MainActivity 成为 Launcher Activity。

如何将我的 MainActivity 设为 Launcher Activity。

public class MapsActivity extends FragmentActivity implements OnMapReadyCallback 
private GoogleMap mMap;
LocationManager locationManager;
LocationListener locationListener;

 protected void onCreate(Bundle savedInstanceState) 
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_maps);
    // 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);


public void onMapReady(GoogleMap googleMap) 
    Toast.makeText(this, "inside onMapReady()", Toast.LENGTH_SHORT).show();//doesn't appear
    Log.i("hurray:","inside onMapReady()");//doesn't appear
    mMap = googleMap;
    locationManager = (LocationManager) this.getSystemService(Context.LOCATION_SERVICE);
    locationListener = new LocationListener() 
        @Override
        public void onLocationChanged(@NonNull Location location) 
            if(location != null)
                Toast.makeText(MapsActivity.this, "Location is not null", Toast.LENGTH_SHORT).show();//doesn't appear
                LatLng userLatLngLocation = new LatLng(location.getLatitude(),location.getLongitude());
                MarkerOptions markerOptions = new MarkerOptions();
                markerOptions.position(userLatLngLocation);
                markerOptions.title("Current position");
                markerOptions.icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_ORANGE));
                mMap.addMarker(markerOptions);
                mMap.moveCamera(CameraUpdateFactory.newLatLng(userLatLngLocation));
                mMap.animateCamera(CameraUpdateFactory.zoomTo(10));
                Toast.makeText(getApplicationContext(), location.toString(), Toast.LENGTH_SHORT).show();//does appears sometimes
            
            else
                Toast.makeText(getApplicationContext(), "location is null !", Toast.LENGTH_SHORT).show();
            
        
public void requestLocationPermission() 
        //if permission not granted ask for it
        if (ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED) 
            ActivityCompat.requestPermissions(this, new String[]Manifest.permission.ACCESS_FINE_LOCATION, 1);
        
        //else if location permission is already granted get location updates
        else 
            locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, locationListener);//every 0secs & 0meters
    

public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, int grantResults[]) 
        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
        if (requestCode == 1) 
            if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) 
                if (ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) == PackageManager.PERMISSION_GRANTED || ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) == PackageManager.PERMISSION_GRANTED) 
                    locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, locationListener);
                
            
        
    

MainActivity.java：

public class MainActivity extends AppCompatActivity 
    Button getPopLocationButton;//button to show the Maps
    MapsActivity mapsActivity;
    protected void onCreate(Bundle savedInstanceState) 
        super.onCreate(savedInstanceState);
        setContentView(R.layout.map_screen);
        mapsActivity = new MapsActivity();
        getPopLocationButton = findViewById(R.id.buttonPopLocation); 
                                                                    
        getPopLocationButton.setOnClickListener(new View.OnClickListener() 
            @Override
            public void onClick(View v) 
                setContentView(R.layout.activity_maps); 
            
        );
    

【问题讨论】：

你能在旧问题中检查this solution

@Ahmed 没用 :(

好的，我只是注意到，如果我在 AndroidManifest.xml 中将 MapsActivity 作为启动器活动，则代码可以正常工作，并且在当前用户位置可以看到一个标记，但我希望将 MainActivity 作为我的启动器活动和activity_main.xml 应该有一个名为“显示当前位置”的按钮，点击该按钮时应显示此标记。

【参考方案1】：

好的，我得到了这个工作，

   public void onClick(View view)
    setContentView(R.layout.map); 
 SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
                            .findFragmentById(R.id.map);
                    mapFragment.getMapAsync(MainActivity.this);

【讨论】：

找到了另一个简单的解决方案，我们可以简单地从 MainActivity 启动一个 Intent 到 MapsActivity