如何使用2个公共类，在相同片段中creat函数上受保护的void？

Question

1. 如何在Android Studio的MainActivity java中放置多个类，概述，空缺？我需要同时具有按钮和代码，以使Google地图在同一页面上具有某些限制。应该更改类的什么名称才能起作用。这些代码在独立放置但不能一起放置时有效。如何使它们协同工作？

   
        package com.example.maps;
        import android.content.Intent;
        import android.os.Bundle;
        import android.support.v4.app.FragmentActivity;
        import android.support.v7.app.AppCompatActivity;
        import android.view.View;
        import android.widget.Button;
   
        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.LatLngBounds;
        import com.google.android.gms.maps.model.MarkerOptions;
   
   
        public class FirstFragment extends AppCompatActivity {
           Button button;
           @Override
          protected void onCreate(Bundle savedInstanceState) {
              super.onCreate(savedInstanceState);
              setContentView(R.layout.activity_main);
             button = (Button) findViewById(R.id.button);
             button.setOnClickListener(new View.OnClickListener() {
                  @Override
                  public void onClick(View v) {
                      openFoodFragment();
                   }
              });
           }
          public void openFoodFragment(){
               Intent intent = new Intent(this, FoodFragment.class);
               startActivity(intent);
           }
        }
       public class MainACTIVITY extends FragmentActivity implements OnMapReadyCallback {
   
           GoogleMap mapAPI;
          SupportMapFragment mapFragment;
          @Override
           protected void onCreate(Bundle savedInstanceState) {
              super.onCreate(savedInstanceState);
              setContentView(R.layout.activity_main);
              mapFragment =(SupportMapFragment)
                      getSupportFragmentManager().findFragmentById(R.id.mapAPI);
   
               mapFragment.getMapAsync(this);
           }
           public void openFoodFragment(){
              Intent intent = new Intent(this, FoodFragment.class);
              startActivity(intent);
           }
         @Override
          public void onMapReady(GoogleMap googleMap){
             mapAPI =  googleMap ;
   
             LatLng one = new LatLng(-21.754812, -48.219451);
             LatLng two = new LatLng(-21.787443, -48.113332);
   
            LatLngBounds.Builder builder = new LatLngBounds.Builder();
   
            //add them to builder
            builder.include(one);
            builder.include(two);
   
            LatLngBounds bounds = builder.build();
   
            //get width and height to current display screen
            int width = getResources().getDisplayMetrics().widthPixels;
            int height = getResources().getDisplayMetrics().heightPixels;
            int padding = (int) (width * 0.20);
            mapAPI.setLatLngBoundsForCameraTarget(bounds);
             mapAPI.moveCamera(CameraUpdateFactory.newLatLngBounds(bounds, width, height, padding));
   
             //set zoom to level to current so that you won't be able to zoom out viz. move outside       bounds
            mapAPI.setMinZoomPreference(mapAPI.getCameraPosition().zoom);
   
   
            LatLng Kampai = new LatLng(-21.780985, -48.186859);
            mapAPI.addMarker(new MarkerOptions().position(Kampai).title("Kampai"));
            mapAPI.moveCamera(CameraUpdateFactory.newLatLng(Kampai));
   
            }
   
            }  
   

Answer 1

是的，可以将它们放在同一个文件中，但是您的mainACTIVITY必须位于FirstFragment内，而这不会发生，您需要移除最底部的括号并将其放在mainACTIVITY类的开头的正上方，在粘贴之前，先关闭FirstFragment的括号另一个类放入文件。