MainActivity.java

package com.example.owner.stepcounter;

import android.content.Context;
import android.hardware.Sensor;
import android.hardware.SensorEvent;
import android.hardware.SensorEventListener;
import android.hardware.SensorManager;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.TextView;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity implements SensorEventListener{

    private SensorManager sensorManager;
    private TextView txt_steps;
    boolean running = false;

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

        txt_steps = (TextView) findViewById(R.id.txt_steps);

        sensorManager = (SensorManager) getSystemService(Context.SENSOR_SERVICE);
    }

    @Override
    protected void onResume() {
        super.onResume();
        running = true;
        Sensor countSensor = sensorManager.getDefaultSensor(Sensor.TYPE_STEP_COUNTER);

        if (countSensor != null){
            sensorManager.registerListener(this, countSensor, SensorManager.SENSOR_DELAY_UI);
        }
        else {
            Toast.makeText(this, "Step sensor not available!", Toast.LENGTH_SHORT).show();
        }
    }

    @Override
    protected void onPause() {
        super.onPause();
        running = false;
    }

    @Override
    public void onSensorChanged(SensorEvent event) {
        if (running){
            txt_steps.setText(String.valueOf(event.values[0]));
        }
    }

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

    }
}