Print student details using arrays
class PrintStudentDetailsUsingArrays
{
public static void main(String arg[])
{
String names[] = { "Rajesh", "Suresh", "Ramesh", "Kamlesh", "Vignesh" };
int marks[] = { 45, 78, 83, 77, 93 };
char sections[] = { 'A', 'B', 'A', 'A', 'B' };
for(int i = 0; i < names.length; i++)
{
System.out.println( names[i] + " in section " + sections[i] + " got " + marks[i] + " marks." );
}
}
}
OUTPUTRajesh in section A got 45 marks.
Suresh in section B got 78 marks.
Ramesh in section A got 83 marks.
Kamlesh in section A got 77 marks.
Vignesh in section B got 93 marks.
DESCRIPTIONHere we have created arrays names
, marks
and sections
to store the student details. We used a for
loop to iterate through the elements and print the details. The lengths of the all the arrays are same, hence the first element (index 0) in names
correspond to first element in sections
and marks
array. Similarly the second element (index 1) in names
correspond to second element in sections
and marks
array. So if we want Ramesh details we need to look at 3rd element (index 2) in every array.
THINGS TO TRY
- Add the details of another student Venkatesh in section B with marks 87 and see the output.
- Remove the details of Ramesh i.e. remove
"Ramesh"
from names
array, remove 83
from marks
array and remove the second 'A'
in sections
array and see the output.
- Remove the name of student Suresh from
names
array, but keep his marks and sections and see the output. Observe that the output does not print the marks and sections correctly.
- Remove the marks from
marks
array and section from sections
array for the student Kamlesh, but keep his name in the names
array. When we do this it throws an ArrayIndexOutOfBoundsException
since we do not have the section and name corresponding to the student.
The above program prints the student details, if we want to store additional students or edit the student information, it is risky and error prone. Than storing the details of one student in multiple arrays, it would be better to group all the information belonging to a student in one place. This can be done using
classes.
A
class is a user defined data type comprising of smaller data elements. For
e.g., a student class contains other data like name, marks and section. This way all related information of student can be grouped in one place.
The syntax for creating a class with data is
class classname
{
type variable1;
type variable2;
type variable3;
.....
}
The
class
is a keyword and the
classname is the name of the class. A class can contain multiple variables (or elements) and each variable having a type like
int
,
char
,
double
and every variable has a different name.
So if we want to create a
Student class, it will look like this.
class Student
{
String name;
int marks;
char section;
}
And similarly a
Car class will look like.
class Car
{
String owner;
String registrationNumber;
int numberOfSeats;
double engineCC;
double mileage;
}
As you can see a
class
is comprised of primitive data types and any other
non primitive data types. For
e.g., Car
is comprised of two
String
s, one
int
and two
double
s.
int
and
double
are primitive data types, but
String
is non-primitive data type, which is again comprised of some other primitive data types. Non-primitive data types are also referred as user defined data types.
Creating variables of non-primitive data types is different from primitive data types and it is explained in
Java Classes and Java Objects.