Java: how to implement private abstract methods?

Is it possible to define a private abstract class in Java? How would a Java developer write a construct like below?

public abstract class MyCommand {
    public void execute()
    {
        if (areRequirementsFulfilled())
        {
            executeInternal();
        }
    }
    private abstract void executeInternal();
    private abstract boolean areRequirementsFulfilled();
}