Package org.apache.juneau.commons.reflect

Class ConstructorInfo

java.lang.Object
org.apache.juneau.commons.reflect.ElementInfo
org.apache.juneau.commons.reflect.AccessibleInfo
org.apache.juneau.commons.reflect.ExecutableInfo
org.apache.juneau.commons.reflect.ConstructorInfo
All Implemented Interfaces:
Comparable<ConstructorInfo>, Annotatable
public class ConstructorInfo extends ExecutableInfo implements Comparable<ConstructorInfo>, Annotatable
Lightweight utility class for introspecting information about a Java constructor.

This class provides a convenient wrapper around Constructor that extends the standard Java reflection API with additional functionality for constructor introspection, annotation handling, and instance creation. It extends ExecutableInfo to provide common functionality shared with methods.

Features:
  • Constructor introspection - access constructor metadata, parameters, exceptions
  • Annotation support - get annotations declared on the constructor
  • Instance creation - create new instances with type safety
  • Accessibility control - make private constructors accessible
  • Thread-safe - instances are immutable and safe for concurrent access
Use Cases:
  • Introspecting constructor metadata for code generation or analysis
  • Creating instances of classes dynamically
  • Finding annotations on constructors
  • Working with constructor parameters and exceptions
  • Building frameworks that need to instantiate objects
Usage:

// Get ConstructorInfo from a class ClassInfo ci = ClassInfo.of(MyClass.class); ConstructorInfo ctor = ci.getConstructor(String.class); // Get annotations List<AnnotationInfo<MyAnnotation>> annotations = ctor.getAnnotations(MyAnnotation.class).toList(); // Create instance ctor.accessible(); // Make accessible if private MyClass obj = ctor.invoke("arg");

See Also:

  • Constructor Details

    • ConstructorInfo

      protected ConstructorInfo(ClassInfo declaringClass, Constructor<?> inner)
      Constructor.

      Creates a new ConstructorInfo wrapper for the specified constructor. This constructor is protected and should not be called directly. Use the static factory methods of(Constructor) or obtain ConstructorInfo instances from ClassInfo.getConstructor(Constructor).

      Parameters:
      declaringClass - The ClassInfo for the class that declares this constructor.
      inner - The constructor being wrapped.

  • Method Details

    • of

      public static ConstructorInfo of(ClassInfo declaringClass, Constructor<?> inner)
      Creates a ConstructorInfo wrapper for the specified constructor.
      Example:

      ClassInfo ci = ClassInfo.of(MyClass.class); Constructor<?> c = MyClass.class.getConstructor(String.class); ConstructorInfo ci2 = ConstructorInfo.of(ci, c);

      Parameters:
      declaringClass - The ClassInfo for the class that declares this constructor. Must not be null.
      inner - The constructor being wrapped. Must not be null.
      Returns:
      A new ConstructorInfo object wrapping the constructor.

    • of

      public static ConstructorInfo of(Constructor<?> inner)
      Creates a ConstructorInfo wrapper for the specified constructor.

      This convenience method automatically determines the declaring class from the constructor.

      Example:

      Constructor<?> c = MyClass.class.getConstructor(String.class); ConstructorInfo ci = ConstructorInfo.of(c);

      Parameters:
      inner - The constructor being wrapped. Must not be null.
      Returns:
      A new ConstructorInfo object wrapping the constructor.

    • accessible

      public ConstructorInfo accessible()
      Description copied from class: ExecutableInfo
      Attempts to call x.setAccessible(true) and quietly ignores security exceptions.
      Overrides:
      accessible in class ExecutableInfo
      Returns:
      This object.

    • compareTo

      public int compareTo(ConstructorInfo o)
      Specified by:
      compareTo in interface Comparable<ConstructorInfo>

    • getAnnotatableType

      public AnnotatableType getAnnotatableType()
      Description copied from interface: Annotatable
      Returns the type of this annotatable object.
      Specified by:
      getAnnotatableType in interface Annotatable
      Returns:
      The type of annotatable object this represents.

    • getLabel

      public String getLabel()
      Description copied from interface: Annotatable
      Returns a human-readable label for this annotatable element.

      The label format depends on the type of annotatable:

      • CLASS_TYPE - Simple class name (e.g., "MyClass")
      • METHOD_TYPE - Class and method with parameter types (e.g., "MyClass.myMethod(String,int)")
      • FIELD_TYPE - Class and field name (e.g., "MyClass.myField")
      • CONSTRUCTOR_TYPE - Class and constructor with parameter types (e.g., "MyClass.MyClass(String)")
      • PARAMETER_TYPE - Class, method/constructor, and parameter index (e.g., "MyClass.myMethod[0]")
      • PACKAGE_TYPE - Package name (e.g., "com.example.package")
      Specified by:
      getLabel in interface Annotatable
      Returns:
      The human-readable label for this annotatable element.

    • inner

      public <T> Constructor<T> inner()
      Returns the wrapped constructor.
      Example:

      ConstructorInfo ci = ...; Constructor<MyClass> ctor = ci.inner();

      Type Parameters:
      T - The class type of the constructor.
      Returns:
      The wrapped constructor.

    • equals

      public boolean equals(Object obj)
      Compares this ConstructorInfo with the specified object for equality.

      Two ConstructorInfo objects are considered equal if they wrap the same underlying Constructor object. This delegates to the underlying Constructor.equals(Object) method.

      This method makes ConstructorInfo suitable for use as keys in hash-based collections such as HashMap and HashSet.

      Overrides:
      equals in class Object
      Parameters:
      obj - The object to compare with.
      Returns:
      true if the objects are equal, false otherwise.

    • hashCode

      public int hashCode()
      Returns a hash code value for this ConstructorInfo.

      This delegates to the underlying Constructor.hashCode() method.

      This method makes ConstructorInfo suitable for use as keys in hash-based collections such as HashMap and HashSet.

      Overrides:
      hashCode in class Object
      Returns:
      A hash code value for this ConstructorInfo.

    • newInstance

      public <T> T newInstance(Object... args) throws ExecutableException
      Shortcut for calling the new-instance method on the underlying constructor.
      Type Parameters:
      T - The constructor class type.
      Parameters:
      args - the arguments used for the method call.
      Returns:
      The object returned from the constructor.
      Throws:
      ExecutableException - Exception occurred on invoked constructor/method/field.

    • newInstanceLenient

      public <T> T newInstanceLenient(Object... args) throws ExecutableException
      Shortcut for calling the new-instance method on the underlying constructor using lenient argument matching.

      Lenient matching allows arguments to be matched to parameters based on parameter types.
      Arguments can be in any order.
      Extra arguments are ignored.
      Missing arguments are set to null.

      Type Parameters:
      T - The constructor class type.
      Parameters:
      args - The arguments used for the constructor call.
      Returns:
      The object returned from the constructor.
      Throws:
      ExecutableException - Exception occurred on invoked constructor/method/field.