Create thread

Android
1

Hi, I’m trying to create a thread, I wrote this code but when the thread starts the application stop. How can I fix?
package com.example.matteoarcangeli.tesina

import java.io.BufferedInputStream
import java.net.HttpURLConnection
import java.net.URL

class Macchinetta(var cmd: String) : Thread() {
    
    init {
        run()
        super.start()
    }

    override fun run() {
        val urlConnection = URL("http://192.168.4.1" + '/'.toString() + cmd).openConnection() as HttpURLConnection
        try {
            val inp = BufferedInputStream(urlConnection.inputStream)
            inp.close()
        } finally {
            urlConnection.disconnect()
        }
    }


}
2

Why don’t you just use the thread() function?

Also, what does it mean that the application stops, does it crash or just closes?
Maybe it prints something that can help understand what exactly is happening?

3

Sorry, application stop means that it crash

4

Also in in this way the thread will execute but then application crash

  Thread({
                    val urlConnection = URL("http://192.168.4.1" + '/'.toString() + cmd).openConnection() as HttpURLConnection
                    try {
                        val inp = BufferedInputStream(urlConnection.inputStream)
                        inp.close()
                    } finally {
                        urlConnection.disconnect()
                    }
                }).start()
5

What message is shown when the application crashes?

6

By the way, do not call run() from init, because it should be called automatically from start() method.

7

I solved in this way: I create a thread in the mainactivity, but when I swichon accelerometer app crash

class MainActivity : AppCompatActivity(), SensorEventListener {
    private lateinit var sensorManager: SensorManager
    private lateinit var swAccellerometro: Switch
    private lateinit var txtAccellerometo: TextView
    private lateinit var car: Car



    var background = object : Thread(){
        override fun run() {
            car = Car(URL("http://192.168.4.1"))
        }
    }.start()
    

    override fun onAccuracyChanged(sensor: Sensor?, accuracy: Int) {


    }

    @SuppressLint("SetTextI18n")
    override fun onSensorChanged(event: SensorEvent?) {
        if (swAccellerometro.isChecked) {

            val x = event!!.values[0]
            val y = event.values[1]
            val z = event.values[2]

            if (abs(x) > 0.25 || abs(z) > 0.25) {
                txtAccellerometo.text = fromHtml("<p><b>x: </b> $x</p><p><b>y: </b> $y</p><p><b>z: </b> $z</p>", FROM_HTML_MODE_LEGACY)
                when {
                    x>0.25 -> car.muovi("right")
                  /* (x < 0.25 && x > -0.25) || (x > -0.7 && z < -0.25) -> car.muovi("stop")
                    x > 0.25 -> car.muovi("right")
                    x < -0.25 -> car.muovi("left")
                    z < -0.7 -> car.muovi("forward")
                    z > -0.25 -> car.muovi("backward")*/
                }
            }

        } else
            txtAccellerometo.text = "Accellerometro disabilitato"
    }


    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        sensorManager = getSystemService(Context.SENSOR_SERVICE) as SensorManager
        sensorManager.registerListener(this, sensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER), SensorManager.SENSOR_DELAY_NORMAL)

        swAccellerometro = findViewById(swAcc)
        txtAccellerometo = findViewById(R.id.textView)


        findViewById<View>(R.id.btnAvanti).setOnClickListener {
            car.muovi("forward")
        }

        findViewById<View>(R.id.btnIndietro).setOnClickListener {
            car.muovi("backward")
        }

        findViewById<View>(R.id.btnDestra).setOnClickListener {
            car.muovi("right")
        }

        findViewById<View>(R.id.btnSinistra).setOnClickListener {
            car.muovi("left")
        }

        findViewById<View>(R.id.btnStop).setOnClickListener {
            car.muovi("stop")
        }
    }
}

class Car(private var url:URL) {

    fun muovi(cmd: String) {
        val policy = StrictMode.ThreadPolicy.Builder().permitAll().build()
        StrictMode.setThreadPolicy(policy)

            val urlConnection = URL(url.toString() + '/' + cmd).openConnection() as HttpURLConnection
            try {
                val inp = BufferedInputStream(urlConnection.inputStream)
                inp.close()
            } catch (e: Exception) {
                e.printStackTrace()
            } finally {
                urlConnection.disconnect()
            }
    }

}