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reflection-utils
Set of utilities for JVM to make work with reflection much easier
Features
Gradle
compile 'ru.oleg-cherednik.utils.reflection:reflection-utils:1.0'
Maven
<dependency>
<groupId>ru.oleg-cherednik.utils.reflection</groupId>
<artifactId>reflection-utils</artifactId>
<version>1.0</version>
</dependency>
Usage
To simplify usage of reflection-utils, there're following classes:
- ConstructorUtils - working with
Constructor; - MethodUtils - working with
Method; - FieldUtils - working with
Field; - EnumUtils - working with
Enum; - AccessibleObjectUtils - working with
AccessibleObject;
Person class for examples
package ru.olegcherednik.utils.reflection.data;
public class Person {
private static final String AUTO = "ferrari";
private String name = "defaultName";
private int age = -1;
private boolean marker;
public Person() {}
public Person(String name) {
this.name = name;
}
public Person(String name, int age) {
this.name = name;
this.age = age;
}
public Person(String name, int age, boolean marker) {
this.name = name;
this.age = age;
this.marker = marker;
}
public String getArgZero() {
return "args_0";
}
public String getArgOne(int one) {
return "args_" + one;
}
public String getArgTwo(int one, String two) {
return "args_" + one + '_' + two;
}
public String getArgThree(int one, String two, boolean three) {
return "args_" + one + '_' + two + '_' + three;
}
public static String getStaticArgZero() {
return "static_args_0";
}
public static String getStaticArgOne(int one) {
return "static_args_" + one;
}
public static String getStaticArgTwo(int one, String two) {
return "static_args_" + one + '_' + two;
}
public static String getStaticArgThree(int one, String two, boolean three) {
return "static_args_" + one + '_' + two + '_' + three;
}
}
Person person = new Person();
ConstructorUtils
details
Class object is available to use
Invoke a constructor with no arguments for a given class
Person person = ConstructorUtils.invokeConstructor(Person.class);
Invoke a constructor with exactly one argument for a given class
Person person = ConstructorUtils.invokeConstructor(Person.class,
String.class, "anna");
Invoke a constructor with exactly two arguments for a given class
Person person = ConstructorUtils.invokeConstructor(Person.class,
String.class, "peter",
int.class, 71);
Invoke a constructor with exactly three arguments for a given class
Person person = ConstructorUtils.invokeConstructor(Person.class,
String.class, "marvin",
int.class, 91,
boolean.class, true);
Invoke a constructor with many arguments for a given class
Person person = ConstructorUtils.invokeConstructor(Person.class,
new Class<?>[] { String.class, int.class, boolean.class },
new Object[] { "marvin", 91, true });
Class object is not available and use full class name as string
Define variable with a canonical class name for Person:
String canonicalName = "ru.olegcherednik.utils.reflection.data.Person";
// canonicalName == Person.class.getCanonicalName()
Invoke a constructor with no arguments for class with a given class name
Person person = ConstructorUtils.invokeConstructor(canonicalName);
Invoke a constructor with exactly one argument for class with a given class name
Person person = ConstructorUtils.invokeConstructor(canonicalName,
String.class, "anna");
Invoke a constructor with exactly two arguments for class with a given class name
Person person = ConstructorUtils.invokeConstructor(canonicalName,
String.class, "peter",
int.class, 71);
Invoke a constructor with exactly three arguments for class with a given class name
Person person = ConstructorUtils.invokeConstructor(canonicalName,
String.class, "marvin",
int.class, 91,
boolean.class, true);
Invoke a constructor with any number of arguments for class with a given class name
Person person = ConstructorUtils.invokeConstructor(canonicalName,
new Class<?>[] { String.class, int.class, boolean.class },
new Object[] { "marvin", 91, true });
Constructor object is available to use
Invoke a given constructor providing zero arguments
Constructor<Person> constructor = Person.class.getDeclaredConstructor();
Person person = ConstructorUtils.invokeConstructor(constructor);
Invoke a given constructor providing one argument
Constructor<Person> constructor = Person.class.getDeclaredConstructor(String.class);
Person person = ConstructorUtils.invokeConstructor(constructor, "anna");
Invoke a given constructor providing two arguments
Constructor<Person> constructor = Person.class.getDeclaredConstructor(String.class,
int.class);
Person person = ConstructorUtils.invokeConstructor(constructor, "peter", 71);
Invoke a given constructor providing three arguments
Constructor<Person> constructor = Person.class.getDeclaredConstructor(String.class,
int.class,
boolean.class);
Person person = ConstructorUtils.invokeConstructor(constructor, "marvin", 91, true);
MethodUtils
details
In case of method with a given name is not exist in the given class, then the parent class will be used to find the method etc.
Invoke not static method with a given name and no arguments
String argZero = MethodUtils.invokeMethod(person, "getArgZero");
// argZero == "args_0"
Invoke not static method with a given name and exactly 1 argument
String argOne = MethodUtils.invokeMethod(person, "getArgOne"
int.class, 1);
// argOne == "args_1"
Invoke not static method with a given name and exactly 2 arguments
String argTwo = MethodUtils.invokeMethod(person, "getArgTwo"
int.class, 1,
String.class, "x2");
// argTwo == "args_1_x2"
Invoke not static method with a given name and exactly 3 arguments
String argThree = MethodUtils.invokeMethod(person, "getArgThree"
int.class, 1,
String.class, "x2",
boolean.class, true);
// argThree == "args_1_x2_true"
Invoke not static method with a given name and any number of arguments
String argThree = MethodUtils.invokeMethod(person, "getArgThree"
new Class<?>[] { int.class, String.class, boolean.class },
new Object[] { 1, "x2", true });
// argThree == "args_1_x2_true"
Invoke not static method with given arguments
Method method = person.getClass().getDeclaredMethod("getArgThree");
String argThree = MethodUtils.invokeMethod(person, method, 1, "x2", true);
// argThree == "args_1_x2_true"
Invoke static method with a given name and no arguments
String staticArgZero = MethodUtils.invokeMethod(Person.class, "getStaticArgZero");
// staticArgZero == "static_args_0"
Invoke static method with a given name and exactly 1 argument
String staticArgOne = MethodUtils.invokeMethod(Person.class, "getStaticArgOne"
int.class, 1);
// staticArgOne == "static_args_1"
Invoke static method with a given name and exactly 2 arguments
String staticArgTwo = MethodUtils.invokeMethod(Person.class, "getStaticArgTwo"
int.class, 1,
String.class, "x2");
// staticArgTwo == "static_args_1_x2"
Invoke static method with a given name and exactly 3 arguments
String staticArgThree = MethodUtils.invokeMethod(Person.class, "getStaticArgThree"
int.class, 1,
String.class, "x2",
boolean.class, true);
// staticArgThree == "static_args_1_x2_true"
Invoke static method with a given name and any number of arguments
String staticArgThree = MethodUtils.invokeMethod(Person.class, "getStaticArgThree"
new Class<?>[] { int.class, String.class, boolean.class },
new Object[] { 1, "x2", true });
// staticArgThree == "args_1_x2_true"
Invoke static method with given arguments
Method method = Person.class.getDeclaredMethod("getStaticArgThree");
String staticArgThree = MethodUtils.invokeMethod(method, 1, "x2", true);
// staticArgThree == "args_1_x2_true"
Retrieve method return type
Method method = Person.class.getDeclaredMethod("getArgZero");
Class<?> cls = MethodUtils.getReturnType(method);
// cls == String.class
In case it's possible that given method could be null then default value can be provided:
Class<?> cls = MethodUtils.getReturnType(null, int.class);
// cls == int.class
FieldUtils
details
In case of filed with a given name is not exist in the given class, then the parent class will be used to find the field etc.
Get the value of the non-static field
Field field = person.getClass().getDeclaredField("name");
String name = FieldUtils.getFieldValue(person, field);
// name == "defaultName"
Get the value of the non-static field with a given name
String name = FieldUtils.getFieldValue(person, "name");
// name == "defaultName"
Get the value of the static field
Field field = Person.class.getDeclaredField("AUTO");
String auto = FieldUtils.getFieldValue(person, field);
// auto == "ferrari"
Get the value of the static field with a given name
String auto = FieldUtils.getFieldValue(Person.class, "AUTO");
// auto == "ferrari"
Set given value to the non-static field
Field field = person.getClass().getDeclaredField("name");
FieldUtils.setFieldValue(person, field, "anna");
// person.name == "anna"
Set given value to the non-static field with a given name
FieldUtils.getFieldValue(Person.class , "name", "anna");
// person.name == "anna"
Call given consumer for the non-static field
Field field = person.getClass().getDeclaredField("name");
Consumer<Field> task = f -> f.set(person, "anna")
FieldUtils.setFieldValue(field, task);
// person.name == "anna"
Call given consumer for the non-static field with a given name
Consumer<Field> task = f -> f.set(person, "anna")
FieldUtils.setFieldValue(person, "name", task);
// person.name == "anna"
Set given value to the static field
Field field = Prson.getClass().getDeclaredField("AUTO");
FieldUtils.setStaticFieldValue(field, "mercedes");
// Person.AUTO == "mercedes"
Set given value to the static field with a given name
FieldUtils.setStaticFieldValue(Person.class, "AUTO", "mercedes");
// Person.AUTO == "mercedes"
Call given consumer for the static field
Field field = Person.class.getDeclaredField("AUTO");
Consumer<Field> task = f -> f.set(null, "mercedes")
FieldUtils.setStaticFieldValue(field, task);
// Person.AUTO == "mercedes"
Call given consumer for the static field with a given name
Consumer<Field> task = f -> f.set(null, "mercedes")
FieldUtils.setStaticFieldValue(Person.class, "AUTO", task);
// Person.AUTO == "mercedes"
Retrieve filed value type
Field field = person.getClass().getDeclaredField("name");
Class<?> cls = FieldUtils.getType(field);
// cls == String.class
In case it's possible that given field could be null then default value can be provided:
Class<?> cls = FieldUtils.getType(null, int.class);
// cls == int.class
EnumUtils
details
Add new constant to the given enum
enum CarBrand {
BMW,
MERCEDES
}
EnumUtils.addConstant(CarBrand.class, "AUDI");
AccessibleObjectUtils
details
Invoke consumer on the accessible object
Use consumer to do any activity on the given accessible object and no return any value.
Person person = new Person();
Field field = person.getClass().getDeclaredField("name");
Consumer<Field> task = f -> f.set(person, "oleg");
AccessibleObjectUtils.invokeConsumer(field, task);
Invoke function on the accessible object
Use function to do any activity on the given accessible object and return a value
Person person = new Person();
Method method = person.getClass().getDeclaredMethod("getCity");
Function<Method, String> task = m -> (String)m.invoke(person);
String city = AccessibleObjectUtils.invokeFunction(field, task);
Invoke not static accessible object
An accessible object could be either Field or Method.
Person person = new Person();
Field field = data.getClass().getDeclaredField("name");
AccessibleObjectUtils.invoke(person, field);
Invoke static accessible object
An accessible object could be either Field or Method.
Field field = data.getClass().getDeclaredField("AUTO");
String auto1 = AccessibleObjectUtils.invoke(field);
String auto2 = AccessibleObjectUtils.invoke(null, field); // alternative