org.klojang.invoke.Setter Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of klojang-invoke Show documentation

Klojang Invoke is a Java module focused on path-based object access and dynamic invocation. Its central classes are the Path class and the PathWalker class. The Path class captures a path through an object graph. For example "employee.address.city". The PathWalker class lets you read from and write to a wide variety of types using Path objects.

The newest version!

package org.klojang.invoke;

import org.klojang.util.ExceptionMethods;

import java.lang.invoke.MethodHandle;
import java.lang.reflect.Method;

import static java.lang.invoke.MethodHandles.publicLookup;

/**
 * Represents a setter for a single property.
 *
 * @author Ayco Holleman
 */
public final class Setter {

  private final Class declaredIn;
  private final Class paramType;
  private final MethodHandle mh;
  private final String property;

  Setter(Method method, String property) {
    this.declaredIn = method.getDeclaringClass();
    this.paramType = method.getParameterTypes()[0];
    this.property = property;
    try {
      this.mh = publicLookup().unreflect(method);
    } catch (IllegalAccessException e) {
      throw ExceptionMethods.uncheck(e);
    }
  }

  /**
   * Returns the name of the property being set by this {@code Setter}.
   *
   * @return the name of the property being set by this {@code Setter}
   */
  public String getProperty() {
    return property;
  }

  /**
   * Returns the type of the property.
   *
   * @return the type of the property
   */
  public Class getParamType() {
    return paramType;
  }

  /**
   * Sets the property on the specified bean to the specified value.
   *
   * @param bean the object receiving the value
   * @param value the value
   * @throws IllegalAssignmentException If the value cannot be cast to the type of the
   * property, or if the value is {@code null} and the property has a primitive type. This
   * is a {@link RuntimeException}, but you might still want to catch it as it can often
   * be handled in a meaningful way.
   * @throws Throwable The unspecified {@code Throwable} associated with calls to
   * {@link MethodHandle#invoke(Object...) MethodHandle.invoke}.
   */
  public void write(Object bean, Object value)
        throws IllegalAssignmentException, Throwable {
    if (value == null) {
      if (getParamType().isPrimitive()) {
        throw illegalAssignment(null);
      }
    }
    try {
      mh.invoke(bean, value);
    } catch (ClassCastException e) {
      throw illegalAssignment(value);
    }
  }

  /**
   * Generates an {@link IllegalAssignmentException} indicating that the specified value
   * cannot be assigned to the property encapsulated by this {@code Setter}.
   *
   * @param value the value
   * @return An {@link IllegalAssignmentException} for the specified value
   */
  public IllegalAssignmentException illegalAssignment(Object value) {
    return new IllegalAssignmentException(
          declaredIn,
          property,
          getParamType(),
          value);
  }

}