String Handling

Question 1

String is available under which package

Answer 1

java.lang

Question 2

Assigning string

Answer 2

1. Direct assignment
2. Assignment using new keyword

Question 3

Char charAt(int index) does what

Answer 3

Returns character from given index number

Question 4

What does int index of(char ch) do

Answer 4

Returns first occurence of character from given index number

Question 5

What does string substring (int start_index) do

Answer 5

Extracts all characters after the given index number

Question 6

Syntax of replace function

Answer 6

String.replace(character to replace, character to appear)

Question 7

What does String 1 concat(String 2) do

Answer 7

Joins two strings together

Question 8

What does String trim() do

Answer 8

Remove leading and trailing blanks from a string

Question 9

What does String Boolean ends with(String s) and startsWith do?

Answer 9

Check if a suffix and prefix is present respectively

Question 10

What does primitive type valueOf(String s) do?

Answer 10

Used to covert a string to primitive data type of respective wrapper class

Question 11

What is StringBuffer

Answer 11

Another type of class with some added functionality to handle strings. You can declare object of StringBuffer type

Question 12

characteristics of StringBuffer

Answer 12

1. refers to specific length in memory to contain characters
2. length can be changed using setLength() function.
3. if the String has a bigger length than of StringBuffer object, then extra characters are truncated
4. if string has a shorter length than StringBuffer object, extra characters such as ‘\u0000’ are in empty spaces

Question 13

what is append() used for

Answer 13

to add a string at the end of another string

Question 14

what is setCharAt(index, character) used for

Answer 14

replace a character with another character available at specific index of string.

Question 15

what is insert(int index, String) used for

Answer 15

insert a String at a specified index

Question 16

what is delete(int index1, int index2) used for

Answer 16

to delete characters from one index to another index in the given string

Question 17

what is setLength(int value) used for?

Answer 17

when length of StringBuffer variable is not sufficient to store a string, length of variable can be increased as per our requirement

Question 18

what is reverse() used for

Answer 18

reverse characters of a given string