Today we gonna see array.
What is array?
Collection of similar (datatype) elements stored continuously.
- It is index based.
- Index starts from 0(zero).
- Index ends at length-1.
- In java array is an object
Array declaration.
datatype[] referencename= new datatype[int] variable
array length is integer
ex:
array
int[] arr= new int[6]
| A0 | A1 | A2 | A3 | A4 | A5 |
Ex:
char[] name=new char[10]
Boolean[] pass=new boolean[5]
String[] names=new string[20]
In this area we see some compilation error and run time error
in compile time error not shown below
package selva.w4;
public class Array {
public static void main(String[] args) {
// TODO Auto-generated method stub
int[] i=new int[10];
System.out.println(i[14]);
<a href=”https://www.javatpoint.com/method-overriding-in-java”>Method Overriding</a>
}
}
shown run time error
Exception in thread “main” java.lang.ArrayIndexOutOfBoundsException: Index 14 out of bounds for length 10
at selva.w4.Array.main(Array.java:9)
Try this one
float[] marks=new float[-5]
package selva.w4;
public class Array {
public static void main(String[] args) {
// TODO Auto-generated method stub
float[] marks=new float[10];
System.out.println(marks[0]);
byte[] b=new byte[5];
System.out.println(b[0]);
short[] s=new short[10];
System.out.println(s[0]);
int[] i=new int[10];
System.out.println(i[-5]);
}
}
result
0.0
0
0
Exception in thread “main” java.lang.ArrayIndexOutOfBoundsException: Index -5 out of bounds for length 10
at selva.w4.Array.main(Array.java:15)
example
array declaration type
package selva.w4;
public class marks {
public static void main(String[] args) {
// TODO Auto-generated method stub
int[] i=new int[10];
i[0]=90;
i[1]=89;
i[2]=97;
System.out.println(i[0]);
System.out.println(i[1]);
System.out.println(i[2]);
}
}
result
90
89
97
value insulation type
package selva.w4;
public class marks {
public static void main(String[] args) {
// TODO Auto-generated method stub
int[] i=new int[10];
int[] i1 = {90,89,97};
System.out.println(i1[0]);
System.out.println(i1[1]);
System.out.println(i1[2]);
}
}
result
90
89
97
assign size directly
package selva.w4;
public class Valueinsulationtype {
public static void main(String[] args) {
// TODO Auto-generated method stub
//int[] i=new int[10];
//int[] i1 = {90,89,97};
//System.out.println(i);//print the hash code for security purpose
//System.out.println(i1[0]);
//System.out.println(i1[1]);
//System.out.println(i1[2]);
int i=0;
int[] marks= {90,87,97};
while(i<marks.length) {
System.out.println(marks[i]);
i++;
}
}
}
90
87
97
note
In java array is a object(memory reference)
object has state and behaviour(action)
state – attributes
ex:
shirt.size
price
indian
action- methods
shirt.wear()
note
java has a some predefined packages
ex:
java.lang
provide string and systems
java.util
utility classes
java.net
it provide network related protocol
java.io
file reading
java.awt
web tool kit
java.javax
used for extension
java.lang there is no need to import. But other classes are need to import.
ARRAY USING FOR LOOP AND SCANNER CLASS
package selva.w4;
import java.util.Scanner;
public class Arrayusingforloop {
public static void main(String[] args) {
// TODO Auto-generated method stub
int[] marks1= new int[5];
for(int i=0; i<5; i++)
{
System.out.println(“enter marks”);
Scanner sc=new Scanner(System.in);
marks1[i]=sc.nextInt();
}
}
}
RESULT
enter marks
1
enter marks
2
enter marks
32
enter marks
4
enter marks
54
in this type we given length and input also using scanner class
note
scanner class imports given before the loop not inside the loop, while length and input given to program inside and outside the loop
package selva.w4;
import java.util.Scanner;
public class Arrayusingforloop {
public static void main(String[] args) {
Scanner sc=new Scanner(System.in);
System.out.println(“enter length”);
int len=sc.nextInt();
int[] marks1= new int[len];
for(int i=0; i<len; i++)
{
System.out.println(“enter marks”);
marks1[i]=sc.nextInt();
}
}
}
result
enter length
2
enter marks
1
enter marks
2
selvakrish 