Arrays

An array is an object of reference type which contains a fixed number of components of the same type; the length of an array is immutable. Creating an instance of an array requires knowledge of the length and component type. Each component may be a primitive type (such as byte, int, or double), a reference type (such as String, Object, or java.nio.CharBuffer), or an array. Multi-dimensional arrays are really just arrays which contain components of array type.

Arrays are implemented in the Java virtual machine. The only methods on arrays are those inherited from Object. The length of an array is not part of its type; arrays have a length field which is accessible via java.lang.reflect.Array.getLength().

Reflection provides methods for accessing array types and array component types, creating new arrays, and retrieving and setting array component values. The following sections include examples of common operations on arrays:

• Identifying Array Types describes how to determine if a class member is a field of array type
• Creating New Arrays illustrates how to create new instances of arrays with simple and complex component types
• Getting and Setting Arrays and Their Components shows how to access fields of type array and individually access array elements
• Troubleshooting covers common errors and programming misconceptions

All of these operations are supported via static methods in java.lang.reflect.Array.