Java集合排序，

Java集合排序，

    public static void main(String[] args) {
    	Dog dog1 = new Dog();
    	dog1.setName("Dog1");
    	
    	Dog dog2 = new Dog();
    	dog2.setName("Dog2");
    	
    	Dog dog3 = new Dog();
    	Dog dog4 = null;
    	
    	List<Dog> dogs = new ArrayList<Dog>();
    	dogs.add(dog1);
    	dogs.add(dog2);
    	dogs.add(dog3);
    	dogs.add(dog4);
    	
        Collections.sort(dogs, new Comparator<Dog>() {// 按名称排序
            public int compare(Dog d1, Dog d2) {
                String n1 = "";
                String n2 = "";
                if(d1 !=null && StringUtils.isNotBlank(d1.getName())){
                	n1 = d1.getName();
                }
                if(d2 !=null && StringUtils.isNotBlank(d2.getName())){
                	n2 = d2.getName();
                }
                //	return n1.compareTo(n2);//升序
                return n2.compareTo(n1);//降序
            }
        });
        
        for(Dog dog:dogs){
        	if(dog == null){
        		System.out.println("Dog is null");
        	}else if(dog.getName() == null){
        		System.out.println("Dog'name is null");
        	}else {
        		System.out.println(dog.getName());
        	}
        }
    }

输出：

Dog2
Dog1
Dog'name is null
Dog is null