Summary

Add additional predicates to categorize and group constants in ElementKind.

Problem

Clients of the ElementKind API such as javadoc, may supply their own predicates. Such predicates have a greater risk of getting out of date with changes to the language than predicates supplied an maintained by the API itself.

Solution

Add some natural predicates.

Specification

--- a/src/java.compiler/share/classes/javax/lang/model/element/ElementKind.java
+++ b/src/java.compiler/share/classes/javax/lang/model/element/ElementKind.java
@@ -151,6 +150,17 @@ public enum ElementKind {
         return this == INTERFACE || this == ANNOTATION_TYPE;
     }

+    /**
+     * {@return {@code true} if this is a kind of declared type, a
+     * {@linkplain #isClass() class} or an {@linkplain #isInterface()
+     * interface}, and {@code false} otherwise}
+     *
+     * @since 19
+     */
+    public boolean isDeclaredType() {
+        return isClass() || isInterface();
+    }
+
     /**
      * Returns {@code true} if this is a kind of field:
      * either {@code FIELD} or {@code ENUM_CONSTANT}.
@@ -160,4 +170,50 @@ public enum ElementKind {
     public boolean isField() {
         return this == FIELD || this == ENUM_CONSTANT;
     }
+
+    /**
+     * Returns {@code true} if this is a kind of executable: either
+     * {@code METHOD} or {@code CONSTRUCTOR} or {@code STATIC_INIT} or
+     * {@code INSTANCE_INIT}.
+     *
+     * @return {@code true} if this is a kind of executable
+     * @since 19
+     */
+    public boolean isExecutable() {
+        return switch(this){
+        case METHOD, CONSTRUCTOR, STATIC_INIT, INSTANCE_INIT -> true;
+        default -> false;
+        };
+    }
+
+    /**
+     * Returns {@code true} if this is a kind of initializer: either
+     * {@code STATIC_INIT} or {@code INSTANCE_INIT}.
+     *
+     * @return {@code true} if this is a kind of initializer
+     * @since 19
+     */
+    public boolean isInitializer() {
+        return switch(this){
+        case STATIC_INIT, INSTANCE_INIT -> true;
+        default -> false;
+        };
+    }
+    /**
+     * Returns {@code true} if this is a kind of variable: including
+     * {@code ENUM_CONSTANT}, {@code FIELD}, {@code PARAMETER},
+     * {@code LOCAL_VARIABLE}, {@code EXCEPTION_PARAMETER},
+     * {@code RESOURCE_VARIABLE}, and {@code BINDING_VARIABLE}.
+     *
+     * @return {@code true} if this is a kind of variable
+     * @since 19
+     */
+    public boolean isVariable() {
+        return switch(this){
+        case ENUM_CONSTANT, FIELD, PARAMETER,
+             LOCAL_VARIABLE, EXCEPTION_PARAMETER, RESOURCE_VARIABLE,
+             BINDING_VARIABLE -> true;
+        default -> false;
+        };
+    }
 }