在hashmap

Question

我是Android新手。我正在使用磁传感器数据创建应用程序。我正在关注另一个基于Wifi的程序的源代码。我的基本课程是

public class MainActivity extends AppCompatActivity implements SensorEventListener{

    Sensor magnetometer;
    SensorManager sm;
    public float a,b,c;

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

        sm = (SensorManager) getSystemService(SENSOR_SERVICE);
        sm.registerListener(this, sm.getDefaultSensor(Sensor.TYPE_MAGNETIC_FIELD), SensorManager.SENSOR_DELAY_NORMAL);
    }

    @Override
    public void onSensorChanged(SensorEvent event) {
        if (event.sensor.getType() == Sensor.TYPE_MAGNETIC_FIELD) {
            getMag(event);
        }
    }

    public static void getMag(SensorEvent event) {
        float[] values = event.values;

        float x = values[0];
        float y = values[1];
        float z = values[2];

        float value = (float)Math.sqrt(Math.pow(x,2) +Math.pow(y,2) + Math.pow(z,2));
    }


    @Override
    protected void onStop() {
        super.onStop();
        finish();
    }

    @Override
    protected void onPause() {
        super.onPause();
        sm.unregisterListener(this);
    }

    @Override
    public void onAccuracyChanged(Sensor sensor, int accuracy) {

    }

}

我可以用这个访问传感器值，但我想要的是在其他类中使用传感器值。在我关注的源代码中，代码用作。

//this is map activity, here for wifi, it just uses "getScanResult() to scan bssid and value, which can be used in onReciveWifiScanResult
public void onStart() {
        super.onStart();

        mReceiver = new BroadcastReceiver ()
        {
            @Override
            public void onReceive(Context c, Intent intent)
            {
                onReceiveWifiScanResults(mWifi.getScanResults());

            }
        };
    }
    
    public void onReceiveWifiScanResults(List<ScanResult> results) {
        
    }
   
    
    
    //And the programmer used it in another class to store to the hashmap
    
    public void onReceiveMagScanResults(List<ScanResult> results) {

                
                HashMap<String, Integer> measurements = new HashMap<String, Integer>();
                for (ScanResult result : results) {
                    measurements.put(result.BSSID, result.level);
                }

                TreeSet<String> keys = new TreeSet<String>();
                keys.addAll(measurements.keySet());
                keys.addAll(mMeasurements.keySet());

那么，我怎么能从我的主要活动的“onSensorChanged”事件中获取我的磁传感器数据，就像上面的广播接收器一样用来代替“onReceiveWifiscanresult”？

任何帮助都会很棒。谢谢。

Answer 1

哦，我找到了答案。现在，我可以将数据存储在SQLite数据库中，然后使用游标来访问数据。然后将数据放入hashmap中。

我使用了这段代码

＆＃13;

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            TextView diff= (TextView) findViewById(R.id.calcDiff);
            SQLiteDatabase db;
            db= openOrCreateDatabase(
                    "Mag_Positioning.db"
                    , SQLiteDatabase.CREATE_IF_NECESSARY
                    , null
            );
            db.setVersion(1);
            db.setLocale(Locale.getDefault());
            db.setLockingEnabled(true);
            Cursor cur = DBHelper.getInstance().getAllData();
            cur.moveToFirst();
            HashMap<PointF, Float> difference = new HashMap<>();

            if (cur.isLast() == false) {
                do{
                    cur1=cur.getInt(2);
                    cur2=cur.getInt(3);
                    PointF location = new PointF(cur1, cur2);
                    z= Float.valueOf(cur.getString(7));
                    total = Float.valueOf(String.valueOf(Math.sqrt(Math.pow((d-z),2))));
                    difference.put(location, total);
                    diff.append("\n" +  difference  +"\n");
                }while(cur.moveToNext());
            }
            cur.close();

＆＃13;

＆＃13;

＆＃13;