Can I perform type conversion using the type found through Java reflection?

Can I perform type conversion using the type found through Java reflection?

public class Dto {
    private String name;
    private int age;

    public Dto(){}
}

It has two fields of different types.

    @Test
    public void reflectionsTest3() throws NoSuchMethodException, InvocationTargetException, InstantiationException, IllegalAccessException {
        Class<Dto> dtoClass = Dto.class;
        Dto dto = dtoClass.getDeclaredConstructor().newInstance();
        Field[] fields = dtoClass.getDeclaredFields();
        Arrays.stream(fields).forEach(field -> {
            field.setAccessible(true); 
            Type T = field.getType();
            field.set(dto,(T) "1");
        });
    }

it make error
I want to detect the type and give it a value that matches the type.
How can I use types?

You can use Map to hold mappings between field class and supplier of value for this class.

public class RandomStuff {

  public static void main(String[] args) throws Exception {
    //...
    Map<Class<?>, Supplier<?>> map = new HashMap<>();
    map.put(String.class, () -> "some string");
    map.put(int.class, () -> 29);
    Arrays.stream(fields).forEach(field -> {
      field.setAccessible(true);
      Class<?> clazz = field.getType();
      try {
        Supplier<?> valueSupplier = map.get(clazz);
        if (valueSupplier == null) {
          // handle no supplier for type
        }
        field.set(dto, valueSupplier.get());
      } catch (IllegalAccessException e) {
        throw new RuntimeException(e);
      }
    });
  }
}

Yes, you can perform type conversion using the type found through Java reflection. Once you have obtained the Class object representing the desired type through reflection, you can use various methods available in Java to perform type conversion or casting.

The code you provided attempts to set the value of each field in the Dto object to the string value "1" using Java reflection. However, it will result in an error because you are trying to perform a type cast from String to T, where T represents the type of the field obtained through reflection.

The problem is that the type T obtained from field.getType() is a Type object and not a concrete class type that can be used for casting. The Type interface does not provide a direct way to cast objects.

You can try changing the code as such any give it a try.

        Class<?> fieldType = field.getType();
        if (fieldType.isAssignableFrom(String.class)) {
            try {
                field.set(dto, "1");
            } catch (IllegalAccessException e) {
                e.printStackTrace();
            }
        }

This snippet, we obtain the fieldType as a Class<?> object instead of Type. Then, we check if the fieldType is assignable from String.class. If it is, we proceed to set the value of the field to "1" using field.set(dto, "1").

We do the type check for String since you are trying to set the field value as "1".