Let's define a few validations on the Todo bean:

   public class Todo {
     private int id; 

     @NotNull
     private String user;

     @Size(min = 9, message = "Enter atleast 10 Characters.")
     private String desc;

Some important points to note are as follows:

• @NotNull: Validates that the user field is not empty
• @Size(min = 9, message = "Enter atleast 10 Characters."): Checks whether the desc field has at least nine characters

There are a number of other annotations that can be used to validate beans. The following are some of the Bean Validation annotations:

• @AssertFalse, @AssertTrue: For Boolean elements. Checks the annotated element.
• @AssertFalse: Checks for false. @Assert checks for true.
• @Future: The annotated element must be a date in the future.
• @Past: The annotated element must be a date in the past.
• @Max: The annotated element must be a number whose value must be lower or equal to the specified maximum.
• @Min: The annotated element must be a number whose value must be higher or equal to the specified minimum.
• @NotNull: The annotated element cannot be null.
• @Pattern: The annotated {@code CharSequence} ;element must match the specified regular expression. The regular expression follows the Java regular expression conventions.
• @Size: The annotated element size must be within the specified boundaries.