minetest/build/android/src/main/java/net.minetest.minetest/MainActivity.java

package net.minetest.minetest;

import android.Manifest;
import android.app.Activity;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.os.Build;
import android.os.Bundle;
import android.widget.Toast;

import androidx.annotation.NonNull;
import androidx.core.app.ActivityCompat;
import androidx.core.content.ContextCompat;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

public class MainActivity extends Activity {
	private final static int PERMISSIONS = 1;
	private static final String[] REQUIRED_SDK_PERMISSIONS = new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE};

	@Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
			checkPermission();
		} else {
			next();
		}
	}

	private void checkPermission() {
		final List<String> missingPermissions = new ArrayList<>();
		// check required permission
		for (final String permission : REQUIRED_SDK_PERMISSIONS) {
			final int result = ContextCompat.checkSelfPermission(this, permission);
			if (result != PackageManager.PERMISSION_GRANTED) {
				missingPermissions.add(permission);
			}
		}
		if (!missingPermissions.isEmpty()) {
			// request permission
			final String[] permissions = missingPermissions
					.toArray(new String[0]);
			ActivityCompat.requestPermissions(this, permissions, PERMISSIONS);
		} else {
			final int[] grantResults = new int[REQUIRED_SDK_PERMISSIONS.length];
			Arrays.fill(grantResults, PackageManager.PERMISSION_GRANTED);
			onRequestPermissionsResult(PERMISSIONS, REQUIRED_SDK_PERMISSIONS,
					grantResults);
		}
	}

	@Override
	public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions,
										   @NonNull int[] grantResults) {
		if (requestCode == PERMISSIONS) {
			for (int index = 0; index < permissions.length; index++) {
				if (grantResults[index] != PackageManager.PERMISSION_GRANTED) {
					// permission not granted - toast and exit
					Toast.makeText(this, R.string.not_granted, Toast.LENGTH_LONG).show();
					finish();
					return;
				}
			}
			// permission were granted - run
			next();
		}
	}

	private void next() {
		Intent intent = new Intent(this, MtNativeActivity.class);
		intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP | Intent.FLAG_ACTIVITY_CLEAR_TASK);
		startActivity(intent);
	}
}