如何动态定义可用作方法中参数的类？

Question

I have a method that I use to validate a POJO in Spring MVC (this allows me to rely on the @Annotation in the POJO and at the same time validate the POJO programmatically whenever and wherever I want without using the annotation @Valid ).

In need to pass the Class of the object to the method in order to validate:

public void validate(Class clazz, Object model, BindingResult result){      
    ...         
    Set<ConstraintViolation<clazz>> constraintViolations=validator.validate((clazz)model);
        for (ConstraintViolation<clazz> constraintViolation : constraintViolations) {
...
}

My code is not correct, since a get the error:

clazz cannot be resolved to a type

How should I edit my code in order to be able to pass to this method any Class I want?

Thank you

Answer 1

You can generify the method

public <T> void setList(Class<T> clazz){
  List<T> list = new ArrayList<>();
}

and call it as follows

setList(Person.class)

Answer 2

You should use generic:

public <T> void setList(){
   List<T> list = new ArrayList<>();
}
...
obj.<Man>setList();
obj.<Woman>setList();
obj.<Person>setList();

or

    public <T> void setList(Class<T> clazz){
      List<T> list = new ArrayList<>();
    }
...
    obj.setList(Woman.class);
    obj.setList(Man.class);
    obj.setList(Person.class);

or

public static class MyClass <T> {
    public <T> void setList() {
        List<T> list = new ArrayList<>();
    }
}  
...
new MyClass<Woman>().setList();
new MyClass<Man>().setList();
new MyClass<Person>().setList();

Update: Instead of code

public void validate(Class clazz, Object model, BindingResult result){      
    ...         
    Set<ConstraintViolation<clazz>> constraintViolations=validator.validate((clazz)model);
        for (ConstraintViolation<clazz> constraintViolation : constraintViolations) {
...
}

use code

public void <T> validate(Class<T> clazz, Object<T> model, BindingResult result){      
    ...         
    Set<ConstraintViolation<T>> constraintViolations=validator.validate(model);
        for (ConstraintViolation<T> constraintViolation : constraintViolations) {
...
}

Answer 3

I guess you don't need a type and can use an unbound wildcard:

public void validate(Class<?> clazz, Object model, BindingResult result){      
    ...         
    Set<ConstraintViolation<?>> constraintViolations=validator.validate(model);
        for (ConstraintViolation<?> constraintViolation : constraintViolations) {
...
}

https://docs.oracle.com/javase/tutorial/extra/generics/wildcards.html