public class Company {
    private static Company instance = new Company();
    
    private Company() {    
    }
    
    public static synchronized Company getInstance() {
        return instance;
    }
}

//被前面人抢先了...
public class Company { 
    private static Company c = null;
    private Company() {
        
    }
    public static synchronized Company getInstance() {
        if(c == null)c = new Company();
        return c;
    }
}

public class Company { 
    private static Company c = null;
    private Company() {
        
    }
    public static synchronized Company getInstance() {
        if(c == null)c = new Company();
        return c;
    }
}