multi-threading, performance and precision consideration

consider the following class:

public class Money {
    private double amount;

    public Money(double amount) {
        super();
        this.amount = amount;
    }

    public double getAmount() {
        return amount;
    }

    public void setAmount(double amount) {
        this.amount = amount;
    }

    public Money multiplyBy( int factor) {
        this.amount *= factor;
        return this;
    }
}

what are the precautions that i can take to make sure that this class doesn't have any problem with multi-threading. have a good performance. while making sure that the money precision is not going to be problem

Ahmad, your question is ambiguous enaugh.

About multithreading: It is not clear what you mean by problems with multi-threading. For instance, that class has not any problem with multi-threading in the sense that it is well-synchronized, but you still can set a state of a Money object into the mess, utilizing it by several threads:

public class Money {
    private volatile double amount;

    public Money(double amount) {
        super();
        this.amount = amount;
    }

    public double getAmount() {
        return amount;
    }

    public synchronized void setAmount(double amount) {
        this.amount = amount;
    }

    public synchronized Money multiplyBy( int factor) {
        this.amount *= factor;
        return this;
    }
}

About money precision: As Andreas answered, see: Why not use Double or Float to represent currency?. Also that one may be interesting: What is the best data type to use for money in Java app?