Can You Access Annotation Values from a Different Class in Java?

Accessing Annotation Values Externally

In Java, is it feasible to retrieve the values of annotations defined in one class within another?

For instance, consider the following annotation and its corresponding accessor methods:

<br>@Column(columnName="firstname")<br>private String firstName;</p>
<p>@Column(columnName="lastname")<br>private String lastName;</p>
<p>public String getFirstName() {<br>  return firstName;<br>}</p>
<p>public void setFirstName(String firstName) {<br>  this.firstName = firstName;<br>}</p>
<p>public String getLastName() {<br>  return lastName;<br>}</p>
<p>public void setLastName(String lastName) {<br>  this.lastName = lastName;<br>}<br>

Is it possible to ascertain the "columnName" value of the @Column annotation from a separate class?

Yes, it is possible if the @Column annotation specifies runtime retention using @Retention(RetentionPolicy.RUNTIME). Here's how:

<code class="java">for (Field f: MyClass.class.getFields()) {
   Column column = f.getAnnotation(Column.class);
   if (column != null)
       System.out.println(column.columnName());
}</code>

Note that MyClass.class.getFields() retrieves only public fields. To access private fields, use MyClass.class.getDeclaredFields().

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