how to validate data types in java?

hi I want to validate the data types in the java code . How should I go about it? 开发者_StackOverflow中文版The data types include String buffer,int , String etc.It would be nice if you could bring the use of validator class here.

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Use hibernate validator and annotate your fields with the kind of types they are supposed to be.

For example

class Datas {

@Pattern(regexp("[a-z]"))
private String here;
@Id
@NotNull
private Integer num;

//
}  

Here you are saying 'here' is allowed to only contain a-z characters and num is an Integer that may not be null. Is something like this what you want? To validate input/output of your data-model ?

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Use Reflection

Object o ; // here is your object
String classSimpleName = o.getClass().getSimpleName();

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get class of object. If it starts with Java.lang .. it is data provided by sun.java

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you can use instanceof, for example:

var userVar = userService.getUser();

if(userVar instanceof User){
   User user = (User) userVar;
}