java object is determined by a reflection of all attributes is empty

Reference links:

       https://developer.aliyun.com/ask/62145?spm=a2c6h.13159736

        https://www.cnblogs.com/DFX339/p/9945771.html

problem analysis:

//判断1  ： 这里会返回 true
User user = null;
if(user == null){
  return true;  
}else{
  return false;  
}

//判断2 ： 这里会返回 false
User user = new User();
if(user == null){
  return true;  
}else{
  return false;  
}

原因： User user = new User(); 这时候已经创建了一个对象，所以user不会为null

The above example is relatively simple, at a glance, it seems there is no problem. 

"  But in fact, when the object you need to determine the object to pass over the tip, simply use the object == null is not enough to judge, because the front will pass over the object is  to determine 2  look like.

Object is not null, but all the properties of the object are null . [except except boolean type, and a sequence of values, there may be other special values please add yo ~]  "

""  Content identified if not clear, please refer to previous blog:  https://www.cnblogs.com/DFX339/p/9896476.html 

Solutions:

Util create classes, properties of the object using the reflection of the determination  

note:

When you need to determine whether the Java object is null, you can start to judge by obj == null, if obj is not equal to null, then decide whether further determined whether all the attributes of obj are null according to business needs.

  public  boolean objCheckIsNull(Object object){
        Class clazz = (Class)object.getClass(); // 得到类对象
        Field fields[] = clazz.getDeclaredFields(); // 得到所有属性
        boolean flag = true; //定义返回结果，默认为true
        for(Field field : fields){
            field.setAccessible(true);
            Object fieldValue = null;
            try {
                fieldValue = field.get(object); //得到属性值
                Type fieldType =field.getGenericType();//得到属性类型
                String fieldName = field.getName(); // 得到属性名
                System.out.println("属性类型："+fieldType+",属性名："+fieldName+",属性值："+fieldValue);
            } catch (IllegalArgumentException e) {
                e.printStackTrace();
            } catch (IllegalAccessException e) {
                e.printStackTrace();
            }
            if(fieldValue != null){  //只要有一个属性值不为null 就返回false 表示对象不为null
                flag = false;
                break;
            }
        }
        return flag;
    }