This document discusses a Java lab lecture on string handling in Java. It covers string constructors, methods of the String class like length(), toUpperCase(), equals(), and compareTo(). The objective is for students to develop basic understanding and skills in Java, specifically working with strings. Key methods covered include length(), toUpperCase(), equals(), equalsIgnoreCase(), and compareTo().

1. Program: B.Tech, CSE, 3rdsem, 2nd year
CS 306: Java Lab
Unit-1
Ravi Parashar
Assistant Professor, Computer Science & Engineering
July-Dec, 2021 / Lecture No. 13
Part II-String handling in Java

2. Outlines
• Prerequisite
• Objective
• String constructors
• Methods of String class
• Learning Outcome
• References

3. Prerequisite
• Basics understanding of C/C++ language.
• Logic building skills.
• Experience writing code in a any programming language.

4. Objective
• To acquire Basic understanding in Java
• To develop the skill of working in Java
•To able to understand string of Java

5. String Constructors
1.String()- it is default constructor ,used to create empty string.
Syntax:-
String x=new String();
Here x is an object.
2.String(string):- it is parameterized constructor.
Syntax:- String x= new String(“Gwalior”);
3.String(char[],int p,int n):- In this p is position from where
characters are read,n is the number of characters to be read.
5
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6. Program for parameterized constructor
class check
{
public static void main(String ar[])
{
char x={‘G’,’W’,’A’,’L’,’I’,’O’,’R’};
String x=new String(x,2,3);
System.out.println (x);
}
} 6
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7. Output
ALI
note : - if we write the string as
String s=“GWALIOR”;
Here s,indicates the base address of string.
7
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8. Various methods of String class
1. int length()- this method returns the number of characters on
string.
Ex. Class check
{
public static void main (String ar[])
{
String x= new String(“Gwalior”);
System.out. println(x.length());
}}
8
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9. Output:-
7
9
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10. 2. toUpperCase():- It converts all rhe characters in a string
from lowercase to uppercase.
3.toLowerCase():- It converts all characters from uppercase to
lowercase.
Ex. class check
{
public static void main (String ar[])
{
String z= new String (“ gwalior”);
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11. String p=z.toUpperCase();
System.out.println (p);
System.out.println (z);
} }
Output:-
GWALIOR
gwalior
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12. 4. boolean equals(String)- If we want to compare string
values.If both strings are equal then this method returns true
otherwise returns false.
Ex. class check
{
public static void main(String ar[])
{
String x=new String(“Gwalior”);
String y=new String (“Gwalior”);
12
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13. if(x.equals(y))
{
System.out.println (“equal”);
}
else
System.out.println (“not equal”);
}
Output: equal
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14. 5. boolean equalsIgnoreCase(String):this method ignores the
cases and compares the strings.
6.int compareTo(String):- It is used to compare two strings.
-If string1 is greater than String2 this method returns + ve
value
-If string1 is lesser than string2 then this method returns –ve
value.
-If string1==string2 this function returns zero.
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15. Ex. if((x.compareTo(y))>0)
{
System.out.println (“string1 is greater”);
}
else if(x.compareTo(y))<0)
System.out.println (“String2 is greater”);
else
System.out.println (“both strings are equals”);
}
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16. Learning Outcomes
• Understand the basic concept in Java
• To understand used of Java
• Be able to work in Java

17. References
1. Herbert schildt ,”The complete Reference Java” ,TMH
publications.