1. What are string, string buffer and String builder?
Ans:- String:
String is a final class available in java.lang.package.
String is immutable i.e String object can't be modified
We can create the string class object in three ways
- Using the new operator eg: String s1= new String(“Java”);
- Without new operator as a string literal eg: String s2= “Hello”;
- Cha array[] = {‘j’,’a’,’v’,’a’}; String s3 = new String(array)
String Buffer is a mutable ie. String Buffer object is mutable .
String Buffer object will be created only one way that is using new operator.
String
|
String Buffer
|
String
objects are immutable
|
String
Buffer object are mutable
|
We
can create the string object in two ways
With
new operator
Without
new operator
|
We
can create String Buffer object only in one way
With
new operator
|
String
will use string constant pooling mechanism internally for the reusability of
the string
|
There
is no concept of pooling in the string Buffer
|
When
you do any concatenation of strings always a new String object will be
created for the result
|
When
u do any concatenation then existing string only modified
|
String
class methods are not synchronized
|
Majority
of the string buffer class methods are synchronized.
|
String Builder: String Builder and String Buffer both are same only one difference is String Builder class methods are not Synchronized.
2. What are the differences between these three Final, Finally and
Finalize?
Ans:- Final:
Final is a keyword can be used for the following 3 things
- To declare the final variables i.e., Final variable cannot be modified
- To specify the final methods i.e., Final method cannot be overridden
- To specify the final class i.e., Final classes cannot be inherited
Ans:-
- Garbage collector is form of memory management.
- It mostly uses mark and sweep algorithms.
- It is automatically invoked when program is being run(when JVM starts).
- It can be also called by calling gc() method of run time class or system class in java.
Ans:-
