In Java, an object reference refers to a variable that holds the memory address or location of an object. It is important to understand that in Java, objects are created dynamically in memory using the "new" keyword, and the object reference allows you to access and manipulate that object.
When an object is created, memory is allocated for it, and the object reference is used to store the memory address where the object resides. This reference provides a way to access the object's properties and invoke its methods.
Here's an example that demonstrates the concept of object references in Java:
// Creating an object of the String class
String message = new String("Hello, world!");
// 'message' is the object reference that holds the memory address of the String object
// Accessing the object's properties and methods using the reference
int length = message.length();
System.out.println("Length of the string: " + length);
// Modifying the object through the reference
message = message.toUpperCase();
System.out.println("Modified string: " + message);
In the above example, the "message" variable is an object reference that points to a String object. The reference is used to access the "length()" method to retrieve the length of the string and to invoke the "toUpperCase()" method to change the string to uppercase.
Object references in Java allow for flexibility and enable multiple variables to refer to the same object. Changes made through one reference are reflected when accessed through another reference pointing to the same object. Understanding object references is crucial when working with complex Java programs that involve multiple objects and their interactions.