Question

当尝试使用SeekBar的 progress 控制连接到Arduino板的伺服电机时，我的应用程序崩溃了。我将在下面发布代码，也许有人可以抓住我所缺少的东西。

我提到我正在使用BluetoothHelper，可以在以下地址找到它：https://github.com/BasicAirData/BluetoothHelper

Android代码：

public class CarConnection {
BluetoothManager mBluetoothManager;
BluetoothHelper mBluetoothHelper;
MainActivity mMainActivity;

public CarConnection(MainActivity mainActivity) {
    mMainActivity = mainActivity;
    mBluetoothHelper = new BluetoothHelper();

    mBluetoothHelper.setBluetoothHelperListener(new BluetoothHelper.BluetoothHelperListener() {
        @Override
        public void onBluetoothHelperMessageReceived(BluetoothHelper bluetoothhelper, final String message) {       
            Toast.makeText(mMainActivity, "Message received: " + message, Toast.LENGTH_SHORT).show();
        }

        @Override
        public void onBluetoothHelperConnectionStateChanged(BluetoothHelper bluetoothhelper, boolean isConnected) {
            // Do something, depending on the new connection status
            String connectedStatus = isConnected ? "connected" : "disconnected";
            Toast.makeText(mMainActivity, "Connection status changed: " + connectedStatus, Toast.LENGTH_SHORT).show();
        }
    mBluetoothHelper.Connect("VOLAN BT");

}

public void setAngle(int angle) {
    mBluetoothHelper.SendMessage(Integer.toString(angle));
    Toast.makeText(mMainActivity, "Sent value: " + Integer.toString(angle), Toast.LENGTH_LONG).show();
}

主要活动类别：

protected void onCreate(Bundle savedInstanceState) {

    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    start = (Button) findViewById(R.id.start_sending);
    angleValue = (SeekBar) findViewById(R.id.simple_sb);
    valueSent = (TextView) findViewById(R.id.value_sent);

    final MainActivity mainActivityInstance = this;
    start.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

            CarConnection mCarConnection = new CarConnection(mainActivityInstance);
        }
    });

    angleValue.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {
        @Override
        public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {
            valueSent.setText("Value sent is: " + Integer.toString(progress));
            mCarConnection.setAngle(progress);
        }

        @Override
        public void onStartTrackingTouch(SeekBar seekBar) {

        }

        @Override
        public void onStopTrackingTouch(SeekBar seekBar) {
            mCarConnection.setAngle(seekBar.getProgress());
        }
    });
}

Arduino代码：

#include <Wire.h>
#include <LCD.h>
#include <LiquidCrystal_I2C.h>

#include <SoftwareSerial.h> // TX RX software library for bluetooth

#include <Servo.h> // servo library 
Servo myservo; // servo name

#define outputA 28
#define outputB 30
LiquidCrystal_I2C lcd(0x3F, 2, 1, 0, 4, 5, 6, 7); 
int angle = 0;
int aState;
int aLastState;

int bluetoothTx = 10; // bluetooth tx to 10 pin
int bluetoothRx = 11; // bluetooth rx to 11 pin

SoftwareSerial bluetooth(bluetoothTx, bluetoothRx);

void setup()
{

  // initialize the lcd
  lcd.setBacklightPin(3, POSITIVE);
  lcd.setBacklight(HIGH); //
  lcd.begin(16, 2);
  lcd.clear();

  pinMode(12, OUTPUT);  
  digitalWrite(12, HIGH);

  pinMode(23, OUTPUT);  
  digitalWrite(23, LOW);

  pinMode (outputA, INPUT);
  pinMode (outputB, INPUT);

  myservo.attach(7); // attach servo signal wire to pin 6
  //Setup usb serial connection to computer
  Serial.begin(9600);

  //Setup Bluetooth serial connection to android
  bluetooth.begin(9600);

  aLastState = digitalRead(outputA);



}

void loop()
{
 //Read from bluetooth and write to usb serial
  if(bluetooth.available()> 0 ) // receive number from bluetooth
  {
    int servopos = bluetooth.read(); // save the received number to servopos
    Serial.println(servopos); // serial print servopos current number received from bluetooth
    myservo.write(servopos); // roate the servo the angle received from the android app
  }
  aState = digitalRead(outputA);
  if (aState != aLastState) {
    if (digitalRead(outputB) != aState) {
      angle ++;
    }
    else {
      angle --;
    }
    float angle_1 = angle * (1023.0 / 360);
    float angle2 = angle_1 / (2.84 );
    Serial.print("Position: ");
    Serial.println(angle2);
    lcd.clear();

    lcd.print("Position: ");
    lcd.print(int(angle2));
    lcd.print("");
    lcd.setCursor(0, 1);

  }
  aLastState = aState;
}

当按下“开始”按钮时，手机将以消息“已连接”进行响应！

提前谢谢！

Answer 1

我认为问题在于UI线程中没有调用onBluetoothHelperConnectionStateChanged()（为了不改变UI性能），因此您不能在此处调用Toast.makeText()。

一种可能的解决方案是通过以下方式在您的类CarConnection中实现侦听器：

public void onBluetoothHelperMessageReceived(BluetoothHelper bluetoothhelper, final String message) {
    runOnUiThread(new Runnable() {
        @Override
        public void run() {
            Toast.makeText(mMainActivity, "Message received: " + message, Toast.LENGTH_SHORT).show();
        }
    });
}

通过蓝牙发送的SeekBar值使应用程序崩溃

1 个答案: