java - Android Studio。从其他 Activity 中调用静态方法

public class MainActivity extends AppCompatActivity {

    private static  final int REQUEST_LOCATION=1;

    public static Context gb;

    static LocationManager locationManager;
    public static String latitude,longitude;
    public MainActivity(Context context){
        this.gb = context;
    }


    Button getlocationBtn;
    static TextView showLocationTxt;

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

        //Add permission

        ActivityCompat.requestPermissions(this,new String[]
                {Manifest.permission.ACCESS_FINE_LOCATION}, REQUEST_LOCATION);

        showLocationTxt=findViewById(R.id.show_location);
        getlocationBtn=findViewById(R.id.getLocation);

        getlocationBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                //place the following line on all operations e.g click
                locationManager=(LocationManager) getSystemService(Context.LOCATION_SERVICE);

                //Check gps is enable or not

                if (!locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER))
                {
                    //Write Function To enable gps

                    OnGPS();
                }
                else
                {
                    //GPS is already On then

                    getLocation();
                }
            }
        });

    }

    public static void getLocation() {

        //Check Permissions again

        if (ActivityCompat.checkSelfPermission(gb,Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED
                && ActivityCompat.checkSelfPermission(gb, Manifest.permission.ACCESS_COARSE_LOCATION) !=PackageManager.PERMISSION_GRANTED)
        {
            ActivityCompat.requestPermissions((Activity)gb,new String[]
                    {Manifest.permission.ACCESS_FINE_LOCATION}, REQUEST_LOCATION);
        }
        else
        {
            Location LocationGps= locationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);
            Location LocationNetwork=locationManager.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
            Location LocationPassive=locationManager.getLastKnownLocation(LocationManager.PASSIVE_PROVIDER);

            if (LocationGps !=null)
            {
                double lat=LocationGps.getLatitude();
                double longi=LocationGps.getLongitude();

                latitude=String.valueOf(lat);
                longitude=String.valueOf(longi);

                showLocationTxt.setText("Your Location:"+"\n"+"Latitude= "+latitude+"\n"+"Longitude= "+longitude);
            }
            else if (LocationNetwork !=null)
            {
                double lat=LocationNetwork.getLatitude();
                double longi=LocationNetwork.getLongitude();

                latitude=String.valueOf(lat);
                longitude=String.valueOf(longi);

                showLocationTxt.setText("Your Location:"+"\n"+"Latitude= "+latitude+"\n"+"Longitude= "+longitude);
            }
            else if (LocationPassive !=null)
            {
                double lat=LocationPassive.getLatitude();
                double longi=LocationPassive.getLongitude();

                latitude=String.valueOf(lat);
                longitude=String.valueOf(longi);

                showLocationTxt.setText("Your Location:"+"\n"+"Latitude= "+latitude+"\n"+"Longitude= "+longitude);
            }
            else
            {
                Toast.makeText(gb, "Can't Get Your Location", Toast.LENGTH_SHORT).show();
            }
        }

    }

    private void OnGPS() {

        final AlertDialog.Builder builder= new AlertDialog.Builder(this);

        builder.setMessage("Enable GPS").setCancelable(false).setPositiveButton("YES", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {
                startActivity(new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS));
            }
        }).setNegativeButton("NO", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {

                dialog.cancel();
            }
        });
        final AlertDialog alertDialog=builder.create();
        alertDialog.show();
    }
}

====================通话活动============================ ==

package com.example.currentlocation;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.view.View;
import android.widget.Button;

public class calling extends AppCompatActivity {
    Button btnLoc;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_calling);
        btnLoc = (Button) findViewById(R.id.getLocation);
        btnLoc.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                MainActivity.getLocation();
            }
        });
    }
}

=============================问题=================== ==============

问候！我试图用Java编写代码。我想在一个带有静态修饰符的类中声明所有方法。这样，无论何时需要，我都可以调用该方法并执行与此相关的功能。在给定的示例中，我尝试举杯当前位置，单击按钮后效果很好。但是当我尝试从另一个活动中调用此静态getLocation时，应用程序崩溃了。

最佳答案

这有很多问题，诸如TextView之类的UI元素不应该是静态的。如果要模块化功能，最好编写Utils类。如果实例化了特定的Activity类，即使可以访问非静态方法，也不要尝试访问其他活动的方法。静态方法在Activity中几乎没有用。

Android系统实例化“活动”并调用生命周期方法，以显示和存储该屏幕的信息。活动并非旨在用作常规课程。我建议研究MVC架构和Android活动生命周期。