Java-线程不想启动

Question

I have this console application, but for some reason the thread's run() method doesn't want to start. The code seems long for the first time but I tried to organize it as much as I can.

The result output:

eThread starting!! 

So it seems that CarManager.startFunctionalities() gets executed, but the line eThread.start() is not executed at all because the line "started" is not printed out.

Here is the sourcecode.

The main class:

package rpicar.android;


public class AndroidEmulator{


    public static void main(String args[]) throws InterruptedException {
        CarManager cm = new CarManager ("localhost");
    }
}

CarManager:

package rpicar.android;

import rpicar.common.Direction;
import rpicar.common.EnvironmentData;


public class CarManager {
    private  MotorManager mManager;
    private final String RPIADDRESS = "localhost";
    private Thread mThread; //motor
    private EnvironmentManager eManager;
    private Thread eThread;
    public CarManager(String rpiAddress) {
        //initialize MotorManager
        mManager = new MotorManager(RPIADDRESS);
        //Make a thread for the Motor commands
        mThread = new Thread(mManager);
        //Initialize EnvironmentManager
        eManager = new EnvironmentManager(RPIADDRESS);
        //Makea thread for collecting EnvironmentData
        eThread = new Thread (eThread);
        startFunctionalities();
    }

    public void move(Direction d){
        this.mManager.setDirection(d);
    }

    public EnvironmentData getCurrentEnvironmentData(){
        return this.eManager.getCurrentEnvironmentData();
    }

    private void startFunctionalities(){
        //Start MotorManager for sending movement commands when needed.
        //mThread.start();
        //Start EnvironmentManager to collect EnvironmentData
        System.out.println("eThread starting!! ");
        eThread.start();
    }
}

EnvironmentManager:

package rpicar.android;

import rpicar.common.CarComponent;
import java.io.IOException;
import java.util.logging.Level;
import java.util.logging.Logger;
import rpicar.common.EnvironmentData;


public class EnvironmentManager extends CarComponent implements Runnable{
    private EnvironmentData currentEnvironmentData;

    public EnvironmentManager(String rpiAddress) {
        super(rpiAddress, 2176, true);
        this.currentEnvironmentData = new EnvironmentData();
    }

    public synchronized EnvironmentData getCurrentEnvironmentData() {
        return currentEnvironmentData;
    }

    public synchronized void setCurrentEnvironmentData(EnvironmentData currentEnvironmentData) {
        this.currentEnvironmentData = currentEnvironmentData;
    }

    @Override
    public void run() {
        System.out.println("eThread started!! ");
        super.connect();
        while(true){
            try {
                this.setCurrentEnvironmentData((EnvironmentData) super.in.readObject());
            } catch (IOException ex) {
                super.connect();
            } catch (ClassNotFoundException ex) {
                Logger.getLogger(EnvironmentManager.class.getName()).log(Level.SEVERE, null, ex);
            }    
        }

    }
}

Answer 1

When you create your instance of eThread , you accidentally pass the thread itself to the constructor (or according to the order of the operations, you pass null ).

You should pass eManager to the constructor instead.

 eThread = new Thread (eThread); 

Would become

eThread = new Thread (eManager);

You can protect yourself in the future from this mistake by making the eThread a final field, so you cannot use it before you declare it.