Download Java String Functions Q&A: equals(), compareTo(), and Exception Handling and more Schemes and Mind Maps Computer science in PDF only on Docsity!
Question 1 equals() and ==
equals()
==
It is a method. It is used to check if the contents of two strings are same or not.
It is a relational operator. It is used to check if two variables refer to the same object in memory
Question 2 compareTo() and equals() compareTo()
It compares two strings.The result is a negative, positive or zero integer value depending on whether
the String object precedes, follows or is equal to the String argument equals() It checks if contents of two strings are same or not.The result is true if the contentsare same otherwise it is false.
Question 3
toLowerCase()and toUpperCase()
tolowerCase()
Converts all characters of the String object to lower case Example: String str = "HELLO":
STRING FUNCTION
System.out.printin (str.toLowerCase();
toUpperCase() Converts all characters of the String object to upper case Example: String str = "hello":
System.out.println(str.toUpper Case());
Output of this code snippet will be HELLO.
Question 4 charAt() and substring()
charAt()
It returns a character from the string at the index specified as its argument Itsreturn type is char
A function can only return a single value.
substring() It extracts a part of the string as specified by its arguments and returns the extracted part as a new
string.
Its return type is String.
Question 5 What is exception? Name two exception handling blocks. An exception is an event, which occurs during the execution of a program that disrupts the normal flow of the program's instructions. Two exception handling blocks are try and catch.
Question 6
Useful String Functions: Function
length()
indexOf()
lastIndexOf()
Return Type int
int
int
Use
Tocount number of characters in aString
To calculate index/position of a character in a String
To calculate last occurrence of a character in a String
Example
String a="Hello"; int b=a.length();
Output: 5
String a="Hello"; int b=a.indexOf('e'); Output: 1
String a="Hello"; int b=a.lastindexOf(); Output: 3
compareTolgnoreCase() int
concat()
replace()
Question 7
String
String
Question 8
String
To return difference of ASCIl value of unmatched characters of two Strings if cases are not same.
Ans: java.lang
Tojoin two Strings without any space
To replace a character or String from a String with new one
Difference Between String and StringBuffer
String a="ABC"; String b="abc"
Which package is used for String in Java?
int c=a.compareTo(b);
Output:-
String a="ABC"; String b="abc" String c=a.concat(b) Output: ABCabc String a=" India is my country";
String is immutable, its content cannot StringBuffer is mutable, its content can be changed through its
be changed once created. append(), insert()etc methods.
String b=a.replace("my","our"); Output: India is our country
String operations like concat() create a StringBuffer operations are mutable and don't create new objects on
new String object. each^ operation.
StringBuffer
String is used when you don't need to StringBuffer is preferred when you need to modify the content
modify content frequently. frequently like building a String through multiple additions.
