Get ready for your next Java data structures lesson! Today, we're delving into Primitive Types (int, float, char) and Class Types (Integer, Float, Character). This knowledge is crucial, as these types are used all over Java, and especially in handling Java collections.
Primitive types in Java are the most fundamental form of data. Here are some examples:
Java1int myAge = 10; // integer 2float pi = 3.14f; // decimal number 3char firstInitial = 'A'; // single character
For each primitive type in Java, there's a corresponding class type. These instances convert regular data, such as int, float, or char, into objects with more capabilities:
Java1Integer ageObject = 10; 2Float piObject = 3.14f; 3Character initialObject = 'A';
They look similar to primitive types at first glance, huh? But they act almost entirely differently!
Primitive and class types may seem similar, yet they differ significantly in terms of memory usage, efficiency, and value comparisons. In fact, primitive type is just a value (5, 3.14, 'A'). Class type, however, is an object that holds the value. On top of holding the value, the object provides several additional properties, methods, and characteristics.
Here is a quick comparison of primitive and class types:
null value (meaning "no value")Java compiler supports auto-boxing and auto-unboxing that allows seamless transitions between primitive types and class types. Let's observe below:
Java1int a = 10; // this is a primitive `int` type 2Integer aBoxed = a; // auto-boxing: int to Integer 3System.out.println(aBoxed); // prints: 10 4 5Integer bBoxed = 20; // this is a class type 6int b = bBoxed; // auto-unboxing: Integer to int 7System.out.println(b); // prints: 20
In this code, a auto-boxes from int to Integer, while bBoxed auto-unboxes from Integer to int. This saves us from manual conversions and calling .intValue() on class types in most places!
In Java, Class Types' additional capabilities have various use cases. Consider how only Class types can use built-in methods from Java's object class like .toString(). The .toString() converts our numeric or character data into a string, allowing us to use this data in ways Primitive Types don’t support:
Java1Integer numInt = 10; 2System.out.println(numInt.toString()); // Prints: 10 3System.out.println(numInt.toString().length()); // Prints: 2 4 5int numPrim = 10; 6System.out.println(numPrim.toString()); // Error: int cannot be dereferenced 7System.out.println(numPrim.length()); // Error: int cannot be dereferenced
Class Types also open the portal to Object-Oriented Programming in Java. So, while Primitive types handle basic tasks elegantly, Class types bring new areas within our reach!
Let's see the difference between how you compare two values with primitive and class types. Here is how you compare the primitives:
Java1int x = 5; 2int y = 5; 3System.out.println(x == y); // Returns: true
With class types, the == operator checks the memory locations of two objects, not values. In this case, you'll need to use .equals() or intValue():
Java1Integer x = 500; 2Integer y = 500; 3 4System.out.println(x == y); // Returns: false 5System.out.println(x.equals(y)); // Returns: true 6System.out.println(x.intValue() == y.intValue()); // Returns: true
Bingo! x == y returns false while x.equals(y) returns true.
Congratulations! You've now covered Java's Primitive and Class Types. Understanding these will prove super useful when we dive into Java data structures! Up next, put into practice what you've learned. Let's conquer Java Data Structures!