Downloaded 77 times
Uploaded bychathuranga kasun bamunusingha
Autoboxing And Unboxing In Java
This document discusses autoboxing and unboxing in Java. It explains that autoboxing allows primitive data types to be automatically wrapped into their corresponding wrapper classes when used where an object is expected. Unboxing is the reverse process where the primitive value is automatically extracted from the wrapper class. This simplifies coding by eliminating the need to manually wrap and unwrap values. Autoboxing and unboxing was introduced in Java 5 to make programming with primitive types and wrapper classes more convenient.
More Related Content
Similar to Autoboxing And Unboxing In Java
Autoboxing And Unboxing In Java
- 1. Autoboxing and Unboxingin JAVA Chathuranga Kasun Bamunusingha
- 2. Quick Review ofJava • Java is an oo language • Can view everything as an object
- 3. Quick Review ofJava • Java is an oo language • Can view everything as an object • There are two type of variables in java • Primitive (int,char,bool…..) • Object
- 4. Quick Review ofJava • Java is an oo language • Can view everything as an object • There are two type of variables in java • Primitive (int,char,bool…..) • Object • Simple data types can be converted into objects • Using “Wrapper” classes
- 5. Quick Review ofJava • Wrapper classes wrap primitive data types and give it an object appearance • Int -> Integer • Char -> Character • Use of wrapper classes • To convert simple data types into objects • To convert strings into relavent data types • Ex • Integer.parseInt(“100”);
- 6. Quick Review ofJava • Wrapper classes wrap primitive data types and give it an object appearance • Int -> Integer • Char -> Character
- 7. Quick Review ofJava ● Wrapper class provides methods to wrap and unwrap objects ◦ Ex: ⚫Wrap -> Integer k=new Integer(100); ⚫Unwrap -> int a=k.intValue(); ⚫It simply like a “Chocolate”! ⚫Manufacture wrap the chocolate with some paper(wrapper) ⚫User takes it and remove the paper(wrapper) and eat
- 8. Autoboxing and Unboxing ●Autoboxing ◦ Wrap a primitive data type into its object type
- 9. Autoboxing and Unboxing ●Autoboxing ◦ Wrap a primitive data type into its object type ◦ Unboxing ⚫Unwrap(get the primitive value) from its relevant object
- 10. Autoboxing and Unboxing ●Autoboxing ◦ Wrap a primitive data type into its object type ◦ Unboxing ⚫Unwrap(get the primitive value) from its relevant object ⚫I made some mistakes!!!!!! ⚫ How the “Auto” parts comes to the picture! ⚫ You just wait ;)
- 11. Back To JavaHistory ● I’m going to write some code in java 4.0!
- 12. Back To JavaHistory ● Now I want to add “3” into listOfNumbers arraylist ● listOfNumbers.add(3);
- 13. Back To JavaHistory ● Now I want to add “3” into listOfNumbers arraylist ● listOfNumbers.add(3); ◦ This gives me an ERROR!!!
- 14. Back To JavaHistory ● Now I want to add “3” into listOfNumbers arraylist ● listOfNumbers.add(3); ◦ This gives me an ERROR!!! ◦ There is no add(int) method , only add(object) method
- 15. Back To JavaHistory ● Now I want to add “3” into listOfNumbers arraylist ● listOfNumbers.add(3); ◦ This gives me an ERROR!!! ◦ There is no add(int) method , only add(object) method ◦ listOfNumbers.add(new Integer(3));
- 16. Back To JavaHistory ● If I need to take that number “3” back, then
- 17. Back To JavaHistory ● If I need to take that number “3” back, then ● It comes out as type of Object ◦ Integer one = (Integer) listOfNumbers.get(0);
- 18. Back To JavaHistory ● If I need to take that number “3” back, then ● It comes out as type of Object ◦ Integer one = (Integer) listOfNumbers.get(0); ◦ Finally you can get the primitive out of the Integer • int intOne = one.intValue();
- 19. What is theproblem mate! ● In every time you (the programmer) has to do the wrapping(boxing) and unwrapping (unboxing) manually
- 20. What is theproblem mate! ● In every time you (the programmer) has to do the wrapping(boxing) and unwrapping (unboxing) manually ◦ It makes coding life bit difficult ◦ It can be introduce bugs in the program
- 21. What is theproblem mate! ● In every time you (the programmer) has to do the wrapping(boxing) and unwrapping (unboxing) manually ◦ It makes coding life bit difficult ◦ It can be introduce bugs in the program ◦ How to solve this ?
- 22. What is theproblem mate! ● In every time you (the programmer) has to do the wrapping(boxing) and unwrapping (unboxing) manually ◦ It makes coding life bit difficult ◦ It can be introduce bugs in the program ◦ How to solve this ? • If compiler do this automatically for the programmer then life will be easy! • That exactly java 5 has done! • We called it “Autoboxing and unboxing”
- 23. Back To Java5 ● Let’s do the previous example in java 5
- 24. Back To Java5 ● Let’s do the previous example in java 5 ● Make an ArrayList of type Integer ◦ ArrayList<Integer> listOfNumbers = new ArrayList<Integer>();
- 25. Back To Java5 ● Let’s do the previous example in java 5 ● Make an ArrayList of type Integer ◦ ArrayList<Integer> listOfNumbers = new ArrayList<Integer>(); ◦ Just add it!
- 26. Back To Java5 ● Let’s do the previous example in java 5 ● Make an ArrayList of type Integer ◦ ArrayList<Integer> listOfNumbers = new ArrayList<Integer>(); ◦ Just add it! • listOfNumbers.add(3); • Here converting int 3 into Integer object has been done by the compiler itself (Autoboxing)
- 27. Back To Java5 ● If I need to get the int value from Integer object ,
- 28. Back To Java5 ● If I need to get the int value from Integer object , ◦ int num = listOfNumbers.get(0); ◦ Here getting int value from Integer object is done by the compiler itself
- 29. Back To Java5 ● If I need to get the int value from Integer object , ◦ int num = listOfNumbers.get(0); ◦ Here getting int value from Integer object is done by the compiler itself ◦ That is intValue() method is called by the compiler ◦ We called it “unboxing”!
- 30. Lets Have FunWith Autoboxing and Unboxing! ● As method arguments
- 31. Lets Have FunWith Autoboxing and Unboxing! ● As method arguments ◦ takeNumber method takes an Integer object as input parameter. But we can use int also!
- 32. Lets Have FunWith Autoboxing and Unboxing! ● Return values
- 33. Lets Have FunWith Autoboxing and Unboxing! ● Return values ◦ giveNumber method return int. but it can be used int or Integer type!
- 34. Lets Have FunWith Autoboxing and Unboxing! ● Boolean expressions
- 35. Lets Have FunWith Autoboxing and Unboxing! ● Boolean expressions
- 36. Lets Have FunWith Autoboxing and Unboxing! ● Operations on numbers ◦ Compiler do the trick!
- 37. Lets Have FunWith Autoboxing and Unboxing! ● Assignments
- 38. Lets Have FunWith Autoboxing and Unboxing! ● Assignments
- 39. End OF TheJourney ● That’s all about autoboxing and unboxing!
- 40. End OF TheJourney ● That’s all about autoboxing and unboxing! ● Any questions ???
- 41. End OF TheJourney ● That’s all about autoboxing and unboxing! ● Any questions ??? ● Thank you!