Java: How to use synchronized and volatile

Question

I have two threads. The first thread calls the setX method, the second one calls the getX method. Do I have to set the methods synchronized although i have only one writing thread? And can i also solve my thread problem with the second class and the volatile variable?

public class Test {
    private int x;  

    public synchronized  void setX(int x) {
        this.x = x;
    }

    public synchronized  int getX() {
        return this.x;
    }
}

public class Test2 {
    private volatile int x; 

    public void setX(int x) {
        this.x = x;
    }

    public int getX() {
        return this.x;
    }
}

Answer 1

Rather than use synchronized or volatile here, I'd personally use AtomicInteger:

public class Test {
    private final AtomicInteger x = new AtomicInteger();  

    public void setX(int value) {
        x.set(value);
    }

    public int getX() {
        return x.get();
    }
}

(Note that I've also fixed your get / set - previously your getX was setting, and your setX was getting...)