An Introduction To Wrapper Classes
Posted By : Lakshmi Singh | 29-Oct-2021
Vectors cannot handle primitive data types like int, float, long, char double. Primitive data types may be converted into object types by using the wrapper classes contained in the java.lang package.
| Simple Type | Wrapper Class |
|---|---|
| boolean | Boolean |
| char | Char |
| double | Double |
| float | Float |
| int | Int |
| long | Long |
The wrapper classes have number of unique methods for handling primitive data types and objects.
1. Converting primitive numbers to object number using contructor methods
| Constructor Calling | Conversion Action |
|---|---|
| Integer IntVal = new Integer(i); | Primitive Integer to Integer object |
| Float FloatVal = new Float(f); | Primitive Float to Float object |
| Double DoubleVal = new Double(d); | Primitive Double to Double object |
| Long LongVal = new Long(l); | Primitive Long to Long object |
2. Converting object numbers to primitive numbers using typeValue() method
| Method Calling | Conversion Action |
|---|---|
| int i = val.intValue(); | Object to primitive integer |
| float f = val.floatValue(); | Object to primitive float |
| long l = val.longValue(); | Object to primitive long |
| double d = val.doubleValue(); | Object to primitive double |
3. Converting numbers to strings using toString() method
| Method Calling | Conversion Action |
|---|---|
| str = Integer.toString(i); | Primitive integer to string |
| str =Float.toString(f); | Primitive float to string |
| str =Double.toString(d); | Primitive double to string |
| str = Long.toString(l); | Primitive long to string |
4. Converting string objects to numeric objects using the Static method ValueOf()
| Method Calling | Conversion Action |
|---|---|
| DoubleVal = Double.Valueof(str); | Converts string to Double object |
| FloatVal = Float.Valueof(str); | Converts string to Float object |
| IntVal = Integer.Valueof(str); | Converts string to Integer object |
| LongVal = Long.Valueof(str); | Converts string to Long object |
5. Converting numeric strings to primitive numbers using parsing methods
| Method Calling | Conversion Action |
|---|---|
| int i = Integer.parseInt(str); | Converts string to primitive integer |
| long i = Long.parseLong(str); | Converts string to primitive long |
Note : parseInt() and parseLong() methods throw a NumberFormatException if the value of the str does not represent an integer.
Cookies are important to the proper functioning of a site. To improve your experience, we use cookies to remember log-in details and provide secure log-in, collect statistics to optimize site functionality, and deliver content tailored to your interests. Click Agree and Proceed to accept cookies and go directly to the site or click on View Cookie Settings to see detailed descriptions of the types of cookies and choose whether to accept certain cookies while on the site.
About Author
Lakshmi Singh
She is a backend Developer. She has expertise in Java, JavaScript, JQuery, HTML, CSS, PHP. She is a quick learner to new technologies and adaptive to the environment.