connectivity/wifirtt/WifiRttScan/Application/src/main/java/com/example/android/wifirttscan/MainActivity.java

/*
 * Copyright (C) 2018 Google Inc. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.example.android.wifirttscan;

import android.Manifest.permission;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.os.Bundle;
import android.support.v4.app.ActivityCompat;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.TextView;

/**
 * Displays list of Access Points enabled with WifiRTT (to check distance). Requests location
 * permissions if they are not approved via secondary splash screen explaining why they are needed.
 */
public class MainActivity extends AppCompatActivity {

    private static final String TAG = "MainActivity";

    private boolean mLocationPermissionApproved = false;

    private TextView mOutputTextView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Toolbar toolbar = findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        mOutputTextView = findViewById(R.id.mainOutputTextView);
    }

    public void onClickFindDistancesToAccessPoints(View view) {
        if (mLocationPermissionApproved) {
            Log.d(TAG, "Location Permissions approved! Retrieving Access Points.");
            // TODO: Implement WifiManager + WifiRTT

        } else {
            // On 23+ (M+) devices, fine location not granted. Request permission.
            Intent startIntent = new Intent(this, LocationPermissionRequestActivity.class);
            startActivity(startIntent);
        }
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        int id = item.getItemId();

        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }

    @Override
    protected void onResume() {
        Log.d(TAG, "onResume()");
        super.onResume();

        mLocationPermissionApproved =
                ActivityCompat.checkSelfPermission(this, permission.ACCESS_FINE_LOCATION)
                        == PackageManager.PERMISSION_GRANTED;
    }
}