Java reflection problem: When I have multiple subclasses that inherit a parent class, reflection cannot retrieve some properties from the parent class

Class<?> cls   = bean.getClass();
Field    field = cls.getField(fieldName);
if (field == null) {
return null;
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field.setAccessible(true);
return (Integer) field.get(bean);

For example, if a and b, c and d inherit from F, F has public String name = 'sun', and when I get it, only a and b get this name, c and d get null. Why？ I'm sure I inherited all the F

My current solution is to add static before name, but I don't know the principle, so I hope there is a solution

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