Reflection Array Class in Java
Last Updated : 06 Aug, 2024
The Array class in java.lang.reflect package is a part of the Java Reflection. This class provides static methods to create and access Java arrays dynamically. It is a final class, which means it can’t be instantiated or changed. Only the methods of this class can be used by the class name itself.
The java.util.Arrays class contains various methods for manipulating arrays (such as sorting and searching), whereas this java.lang.reflect.Array class provides static methods to create and access Java arrays dynamically. This Array class keeps the array to be type-safe.
Class Hierarchy
java.lang.Object
↳ java.lang.reflect.Array
Class Declaration
public final class Array
Note: The Array class should be correctly represented as public final class Array. It extends Object implicitly but does not explicitly declare extends Object.
Syntax to use Array:
Array.<function name>;
Methods in Reflection Array Class in Java
| S. No. | Method | Description |
|---|
| 1 | Object get(Object array, int index) | This method returns the value of the indexed component in the specified array object. |
| 2 | boolean getBoolean(Object array, int index) | This method returns the value of the indexed component in the specified array object as a boolean. |
| 3 | byte getByte(Object array, int index) | This method returns the value of the indexed component in the specified array object as a byte. |
| 4 | char getChar(Object array, int index) | This method returns the value of the indexed component in the specified array object as a char. |
| 5 | double getDouble(Object array, int index) | This method returns the value of the indexed component in the specified array object as a double. |
| 6 | float getFloat(Object array, int index) | This method returns the value of the indexed component in the specified array object as a float. |
| 7 | int getInt(Object array, int index) | This method returns the value of the indexed component in the specified array object as an int. |
| 8 | int getLength(Object array) | This method returns the length of the specified array object as an int. |
| 9 | long getLong(Object array, int index) | This method returns the value of the indexed component in the specified array object as a long. |
| 10 | short getShort(Object array, int index) | This method returns the value of the indexed component in the specified array object as a short. |
| 11 | Object newInstance(Class<E> componentType, int length) | This method creates a new array with the specified component type and length. |
| 12 | Object newInstance(Class<E> componentType, int… dimensions) | This method creates a new array with the specified component type and dimensions. |
| 13 | void set(Object array, int index, Object value) | This method sets the value of the indexed component of the specified array object to the specified new value. |
| 14 | void setBoolean(Object array, int index, boolean z) | This method sets the value of the indexed component of the specified array object to the specified boolean value. |
| 15 | void setByte(Object array, int index, byte b) | This method sets the value of the indexed component of the specified array object to the specified byte value. |
| 16 | void setChar(Object array, int index, char c) | This method sets the value of the indexed component of the specified array object to the specified char value. |
| 17 | void setDouble(Object array, int index, double d) | This method sets the value of the indexed component of the specified array object to the specified double value. |
| 18 | void setFloat(Object array, int index, float f) | This method sets the value of the indexed component of the specified array object to the specified float value. |
| 19 | void setInt(Object array, int index, int i) | This method sets the value of the indexed component of the specified array object to the specified int value. |
| 20 | void setLong(Object array, int index, long l) | This method sets the value of the indexed component of the specified array object to the specified long value. |
| 21 | void setShort(Object array, int index, short s) | This method sets the value of the indexed component of the specified array object to the specified short value. |
How to create an Array using java.lang.reflect.Array Class?
Creating an array using reflect.Array Class is different from the usual way. The process to create such an array is as follows:
- Get the size of the array to be created
- To create an array (say of X class), use the newInstance() method of Array class to pass the X class as the type of the array, and the size of the array, as parameters.
Syntax:
X[] arrayOfXType = (X[]) Array.newInstance(X.class, size);
Where X is to be replaced by the type of the array like int, double, etc.
- This method returns an Object array of the given size, then cast into the required X[] type.
- Hence the required array of type X has been created.
Below is an example to create an integer array of size 5, using the Array class:
Example: To create an integer array of size 5:
Java // Java code to create an integer array of size 5, // using the Array class: import java.lang.reflect.Array; import java.util.Arrays; public class GfG { public static void main(String[] args) { // Get the size of the array int sizeOfArray = 5; // Create an integer array // using reflect.Array class // This is done using the newInstance() method int[] intArray = (int[])Array.newInstance( int.class, sizeOfArray); // Printing the Array content System.out.println(Arrays.toString(intArray)); } } How to add elements in an Array using java.lang.reflect.Array Class?
Like creating an array, adding elements in the array using reflect.Array Class is also different from the usual way. The process to add elements in such an array is as follows:
- Get the value of the element to be added.
- Get the index at which the element is to be added.
- To add an element in an array (say of X class), use the setX() method of Array class, where X is to be replaced by the type of the array such as setInt(), setDouble(), etc. This method takes the X[] as the first parameter, the index at which the element is added as the second parameter, and the element as the third parameter in the below syntax.
Syntax:
Array.setX(X[], indexOfInsertion, elementToBeInserted);
Where X is to be replaced by the type of the array like int, double, etc.
- This method inserts the element at the specified index in this array.
- Hence the required element has been inserted into the array.
Below is an example to add an element into an integer array, using the Array class:
Example: To add an element into an integer array:
Java // Java code to add an element into an integer array, // using the Array class: import java.lang.reflect.Array; import java.util.Arrays; public class GfG { public static void main(String[] args) { // Get the size of the array int sizeOfArray = 3; // Create an integer array // using reflect.Array class // This is done using the newInstance() method int[] intArray = (int[])Array.newInstance( int.class, sizeOfArray); // Add elements to the array // This is done using the setInt() method Array.setInt(intArray, 0, 10); Array.setInt(intArray, 1, 20); Array.setInt(intArray, 2, 30); // Printing the Array content System.out.println(Arrays.toString(intArray)); } } How to retrieve elements in an Array using java.lang.reflect.Array Class?
Like creating an array, retrieving elements in the array using reflect.Array Class is also different from the usual way. The process to retrieve elements in such an array is as follows:
- Get the index at which the element is to be retrieved.
- To retrieve an element in an array (say of X class), use the getX() method of Array class, where X is to be replaced by the type of the array such as getInt(), getDouble(), etc. This method takes the X[] as the first parameter and the index at which the element is retrieved as the second parameter in the syntax below.
Syntax:
Array.getX(X[], indexOfRetrieval);
Where X is to be replaced by the type of the array like int, double, etc.
- This method retrieves the element at the specified index from this array.
- Hence the required element has been retrieved from the array.
Below is an example to retrieve an element from an integer array using the Array class:
Example: To retrieve an element from an integer array:
Java // Java code to retrieve an element from an integer array, // using the Array class: import java.lang.reflect.Array; import java.util.Arrays; public class GfG { public static void main(String[] args) { // Get the size of the array int sizeOfArray = 3; // Create an integer array // using reflect.Array class // This is done using the newInstance() method int[] intArray = (int[])Array.newInstance( int.class, sizeOfArray); // Add elements to the array // This is done using the setInt() method Array.setInt(intArray, 0, 10); Array.setInt(intArray, 1, 20); Array.setInt(intArray, 2, 30); // Printing the Array content System.out.println(Arrays.toString(intArray)); // Retrieve elements from the array // This is done using the getInt() method System.out.println("Element at index 0: " + Array.getInt(intArray, 0)); System.out.println("Element at index 1: " + Array.getInt(intArray, 1)); System.out.println("Element at index 2: " + Array.getInt(intArray, 2)); } } Output[10, 20, 30] Element at index 0: 10 Element at index 1: 20 Element at index 2: 30
Similar Reads
Reflection in Java
Reflection is an API that is used to examine or modify the behavior of methods, classes, and interfaces at runtime. The required classes for reflection are provided under java.lang.reflect package which is essential in order to understand reflection. So we are illustrating the package with visual ai
5 min read
Object Class in Java
Object class in Java is present in java.lang package. Every class in Java is directly or indirectly derived from the Object class. If a class does not extend any other class then it is a direct child class of the Java Object class and if it extends another class then it is indirectly derived. The Ob
8 min read
Classes and Objects in Java
In Java, classes and objects are basic concepts of Object Oriented Programming (OOPs) that are used to represent real-world concepts and entities. The class represents a group of objects having similar properties and behavior, or in other words, we can say that a class is a blueprint for objects, wh
12 min read
Array get() Method in Java
The java.lang.reflect.Array.get() is an inbuilt method in Java and is used to return the element at a given index from the specified Array. Syntax Array.get(Object []array, int index) Parameters : This method accepts two mandatory parameters: array: The object array whose index is to be returned. in
3 min read
util.Arrays vs reflect.Array in Java with Examples
Array class in java.lang.reflect package is a part of the Java Reflection. This class provides static methods to create and access Java arrays dynamically. It is a final class, which means it can’t be instantiated or changed. Only the methods of this class can be used by the class name itself. On th
2 min read
Static class in Java
Java allows a class to be defined within another class. These are called Nested Classes. Classes can be static which most developers are aware of, henceforth some classes can be made static in Java. Java supports Static Instance Variables, Static Methods, Static Block, and Static Classes. The class
3 min read
java.lang.reflect.Field Class in Java
The ability of the software to analyze itself is known as Reflection. This is provided by the java.lang.reflect package and elements in Class .Field serves the same purpose as the whole reflection mechanism, analyze a software component and describe its capabilities dynamically, at run time rather t
5 min read
java.lang.reflect.Proxy Class in Java
A proxy class is present in java.lang package. A proxy class has certain methods which are used for creating dynamic proxy classes and instances, and all the classes created by those methods act as subclasses for this proxy class. Class declaration: public class Proxy extends Object implements Seria
4 min read
Triplet Class in JavaTuples
A Triplet is a Tuple from JavaTuples library that deals with 3 elements. Since this Triplet is a generic class, it can hold any type of value in it. Since Triplet is a Tuple, hence it also has all the characteristics of JavaTuples:Â They are TypesafeThey are ImmutableThey are IterableThey are Serial
5 min read
Array set() method in Java
The java.lang.reflect.Array.set() is an inbuilt method in Java and is used to set a specified value to a specified index of a given object array. Syntax Array.set(Object []array, int index, Object value) Parameter : array : This is an array of type Object which is to be updated. index : This is the
3 min read