Outlines of this lecture: - String Class - String Class Methods - String Buffer Class - String Buffer Class Methods - Inner Class - Member Inner Class - Anonymous Inner Class - Local Inner Class - Static Nested Class: - Nested Interface

1. P.1
String
ghadeer-al-hasan ghadeer.al.hasan.95@gmail.com

2. Java String P.2
 Is an object that represents a sequence of character.
 String class is used to create string object.
There are two ways to create String object:
1) string literal.
2) new keyword
P.S: String object are stored in
a special memory area know as string
constant pool.
We used it, to make Java more memory efficient (because no new object
Are created if it exists already in string constant pool).

3. Java String Cont. : P.3
JVM will create a new string object
in normal(non pool) heap memory

4. Java String Compare : P.4

5. Java String Compare Cont. : P.5

6. Java String Concat : P.6
After a string literal, all the + will be treated as
string concatenation operator

7. Java String Substring : P.7

8. Java String Method : P.8

9. StringBuffer class: P.9
 Is used to created mutable string.
 The StringBuffer class in java same as String class except it is mutable.
 It can be changed.

10. StringBuffer class Cont. : P.10

11. toString() method: P.11
 If you to represent any object as a string,
 Returns the string representation of the object.
 Java compiler internally invoked the toString() method on the object when you print it.
 By override the toString() method of the Object class, we can return values of the object.

12. toString() method Cont. : P.12

13. P.13
Inner Class

14. Inner Class : P.14
 Inner class or nested class is a class declared inside the class or interface.
 It can access all the members (data members and methods) of outer class
including private.
 Are used to develop more readable and maintainable code
 Code optimization: it requires less code to write.
Inner class is a part of nested class. Not-static nested classes are know as inner class.
There are two types:
1. Non-static nested class( inner class)
a. member inner class.
b. anonymous inner class.
c. local inner class
2. Static nested class.

15. Member inner class: P.15
 Is a non-static class that is created inside a class but outside a method.
The java compiler created two class files in case of inner class. If you want to
Instantiate inner class, you must have to create the instance of outer class,

16. Anonymous inner class P.16
 Is A class that have no name .
 It should be used if you have to override method of class of interface.

17. Local inner class: P.17
 Is a class created inside a method.
 If you want to invoke the method of local inner class, you must instantiate this
class inside the method.
• Local variable can’t be private,
public or protected.
• Local inner class cannot be
invoked from outside the method.

18. Local inner class: P.18
• Local inner class cannot access non-final local variable till JDK 1.7.
• Since JDK 1.8, it is possible access to access the non-final local variable in it.

19. Local inner class P.19
 Is a class created inside a method.
 If you want to invoke the method of local inner class, you must instantiate this
class inside the method.
• Local variable can’t be private,
public or protected.
• Local inner class cannot be
invoked from outside the method.

20. Static nested class: P.20
 It cannot access non-static data members and methods.
 It can be accessed by outer class name.
• It can access static data members
of outer class including private.

21. Static nested class Cont. : P.21

22. Nested Interface
P.22

23. Nested Interface: P.23
 Is declared within another interface or class.
 It used to group related interfaces.
 It can be easy to maintain.
 It must be public if it is declared inside the interface.
 But it can have any access modifier if declared within the class.
 It is declared static implicitly.

24. Nested Interface Cont. : P.24