util.Arrays vs reflect.Array in Java with Examples

Prerequisite: Array class, Arrays class

The Array class in java.lang.reflect package is a part of the Java Reflection. This class provides static methods to dynamically create and access Java arrays. 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 Arrays class in java.util package is a part of the Java Collection Framework. This class provides static methods to dynamically create and access Java arrays. It consists of only static methods and the methods of Object class. The methods of this class can be used by the class name itself.

Difference between Array and Arrays in Java:

The package of existence:
The Array class exists in the java.lang.reflect package whereas the Arrays class exists in the java.util package.

Class Hierarchy of Array:
```
java.lang.Object
 ↳ java.lang.reflect
  ↳ Class Array
```
Class Hierarchy of Arrays:
```
java.lang.Object
 ↳ java.util
  ↳ Class Arrays
```
Immutability:
The Array class is immutable in nature whereas the Arrays class is not. By immutable, it means that the class cannot be extended or inherited. The Array class is declared as final to achieve immutability.

Class Declaration of Array:
```
public final class Array
    extends Object
```
Class Declaration of Arrays:
```
public class Arrays
    extends Object
```

Usage:
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 dynamically create and access Java arrays. This Array class keeps the array to be type-safe.

Example:

// Java program to show Array vs Arrays 
  
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[] intArray = new int[5]; 
  
        // Add elements into the array 
        // using reflect.Array class 
        Array.setInt(intArray, 0, 10); 
  
        // Printing the Array content 
        // using util.Arrays class 
        System.out.println( 
            Arrays.toString(intArray)); 
    } 
} 

Output:

[10, 0, 0, 0, 0]

My Personal Notes

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