Array:
int a1 = 10; // Only one value at a
time
int a2 = 20;
// To store 100
values, you would need to declare 100 variables,
e.g.,
a1, a2, a3, ..., a100
An array is a collection of
values of the same data type
It can be used to store a
collection of values that are homogeneous (i.e., of the same type).
homogeneous =
same type
// Instead, you can use an array
to store multiple values
// 10, 20, 30
// 1.1f, 2.1f, 4.3f
// 'A','B', 'C'
// "Ram",
"Sita","Raju"
Declaring an Array:
Arrays can be declared in two ways:
Syntax:
datatype varname[] = new
datatype[size];
(or)
datatype[] varname = new datatype[size];
size
represents how many values we can store in the array.
Declare int array:
// Declare an int array with the
name 'arr' and size of 3
int
arr[] = new int[3];
(or)
int[] arr = new int[3];
Declare float array:
// declare a float array with name i.e ‘farr’
and size of array = 3
float farr[] = new float[3];
(or)
float [] farr
= new float [3];
Declare char array:
// declare a char array with name i.e ‘charr’
and size of array = 2
char charr [] = new char[2];
(or)
char [] charr = new char [2];
Declare String array:
// Declare a String array with
the name 'sarr' and size of array = 4
String sarr [] = new String [4];
(or)
String [] sarr = new String [4];
in array, it stores the values in
index no.
The index number starts with 0 and
ends with size of array -1 i.e 2 (3-1)
the first element of the array is
stored at the indexno = 0,
2nd element is stored at the
indexno = 1
...............................
and so on.
Store/assign values in array:
To store or assign values to an array,
you specify the index position where the value should be stored.
//
Declare an int array with the name 'arr' and size of 3
int
arr[] = new int[3];
//
Store the value 10 at index 0
arr[0] =10;
// 10 value is stored at index no =0 in array
// store 20 value at index no =1
arr[1] = 20;
// 20
value is stored at index no =1 in array
//
Access values from array based on index no = 0,1,2...etc
// Access the value stored at
index 0
arr[0] -->
10
// Access the value stored at
index 1
arr[1]
--> 20
...
....
package ArrayBasics;
public class intArrayBasics {
public
static void main(String[] args) {
// create array of int val's and size =3
int
arr [] = new int[3];
// store max 3 values only
// store 10 val index no =0
arr[0]
=10;
// 10 value is stored at index no =0 in array
// store 20 val index no =1
arr
[1] =20;
// 20 val is stored at indexno =1 in array
// store 30 val at index no =2
arr
[2] =30;
//
30 val is stored at index no =2
//
store 40 val at index no =3 --> ???
// 4 th
val size
=3 max
// arr[4] = 40 ; // error : we dont have index no = 4 ..
//here
arr size = 3 index from 0 to size-1 i.e 3-1 = 2 (0-2)
//
Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException:
Index 4 out of bounds for length 3
// at
ArraysBasics.intArray.main(intArray.java:62)
// arr [5]
index no = 0 to 4
// arr [100] 0 to 99
//
display / Access values from array
//
display arr val at index no =0
System.out.println(arr[0]);
System.out.println("Array
value at indexno =0 --> "+ arr[0]);
// 10
//
display arr val at index no =1
System.out.println(arr[1]);//
20
System.out.println("Array
value at indexno =1 --> "+ arr[1]);
////
display arr val at index no =2
System.out.println(arr[2]);// 30
System.out.println("Array
value at indexno =2 -->"+
arr[2]);
}
}
o/p:
10
Array value at indexno =0 -->
10
20
Array value at indexno =1 -->
20
30
Array value at indexno =2 -->30
Float array :
package ArrayBasics;
public class floatArray {
public
static void main(String[] args) {
// int arr[] = new int[3];
//
Declare float array of size =3
float
farr[] = new float[3];
// array name - fArr
//
size of array = 3 - we can store max of 3 float values
//
index no -always starts from 0 and ends
with size of arr -1. i.e 3-1 =2
// index no varies from 0 to 2 -
0,1,2
//
store some float values in array
//
store 1.2f values in float array at indexno =0
farr[0]
= 1.2f;
//
store 2.2f values in float array at indexno =1
farr[1]
= 2.2f;
//
store 3.2f values in float array at indexno =2
farr[2]
= 3.2f;
// display values from float array
System.out.println("val
from float array at index no =0 -->" + farr[0]);
//
1.2
System.out.println("val
from float array at index no =1 -->" + farr[1]);//2.2
System.out.println("val
from float array at index no =2 -->" + farr[2]);//3.2
}
}
o/p:
val from float array at index no
=0 -->1.2
val from float array at index no
=1 -->2.2
val from float array at index no
=2 -->3.2
HW define char array and store
char values and display it
HW Define double array and store
double values and display it
HW Define long array and store
some values and display it
HW Define boolean array and store boolean values and display it
Note:
When working with arrays, it's important to ensure that the type of values
being assigned matches the type of the array.
Example of Type Mismatch:
Ex1:
int iarr[] = new int[3];
iarr[0] = 3.2f; // Type mismatch:
cannot convert from float to int
// int array - can be used store int values only
Ex2:
float farr[] = new float[3];
farr[0] = 25; // 25 gets converted to 25.0
farr[0] = 'A'; // 'A' gets converted to its ASCII value,
65, and then to 65.0
// float array - can be used store decimal
numbers usually (or) it will convert int to float value (or)
else it throws error
Ex3:
farr[0] = true; // Error: cannot convert boolean to float
Assigning a boolean value to a float array results in a type mismatch error.
2. int array - We cannot store 1 float val + 1
double val + 1 char val + 1 boolean
value
int iarr[] =
new int[3];
iarr[0] =
1.23f; // Error: cannot convert from float to int
iarr[0] =
3.2; // Error: cannot convert from
double to int
iarr[0] =
'C'; // 'C' is converted to its ASCII
value, 67, which is valid for int
iarr[0] =
true; // Error: cannot convert from
boolean to int
iarr[0] =
"Ram"; // Error: cannot convert from String to int
Always ensure the values being assigned to an
array match the array's data type to avoid compilation errors.
Note:
In array, we can store same data
type of values
homogeneous values
int
arr --> store only int vaues
float
arr --> store only float values
In General array, we can not
store 1 int val + 1 float + 1 double + 1
char
+ 1 boolean +
1 String
Display values from array using 'for' loop:
package ArrayBasics;
public class intArrayBasics2 {
public
static void main(String[] args) {
//
int array : and store 3 values
int
arr [] = new int[3];// 0 - 3-1 i.e 2
arr[0]
=10;
arr[1]
=20;
arr
[2] =30;
//Display
each values from array using index no
// System.out.println("val at index no
=0 -->"+ arr[0]);
// System.out.println("val at index no
=1 -->"+ arr[1]);
// System.out.println("val at index no
=2 -->"+ arr[2]);
/// 99
// System.out.println("val at index no
=2"+ arr[99]);
//Display
values from array using 'for' loop:
// for(int i=0;i<=3;i++)// i=0, 0+1= 1,
1+1 =2, 2+1 =3
for(int
i=0;i<=2;i++)// i=0, 0+1= 1, 1+1 =2, 2+1 =3
{// 0<=3 true, enters for loop
// 1<=3
true , enters for loop
// 2<=3
true, for loop
// 3<=3 true, enters for loop
System.out.println("values
from array="+ arr[i]);
// arr[0] //
10
//
arr[1] //20
// arr[2] // 30
//
arr[3]// no index no =3 in array.
//so
it throws exception- java.lang.ArrayIndexOutOfBoundsException:
}
}
}
Array length:
In Java, the length of an array
can be accessed using the length
property.
This property returns the number
of elements the array can hold, which is determined when the array is created.
package ArrayBasics;
public class intArrayBasics2 {
public
static void main(String[] args) {
//
int array : and store 3 values
int
arr [] = new int[3];// 0 - 3-1 i.e 2
arr[0]
=10;
arr[1]
=20;
arr
[2] =30;
//
length of array i.e 3
int
le = arr.length;
// 3
// le = 3
System.out.println("Length
of array ="+ le);// 3
// dispay all values from array
using for loop and lenhth of
array
// for(int i=0;i<=2;i++)
// use length of array
// for(int
i=0;i<=le-1;i++)
for(int i=0;i<=arr.length-1;i++)
{ // 3-1=2
System.out.println(arr[i]);
}
// Values from
array =10
// Values from
array =20
// Values from
array =30
}
}
o/p:
Length of array =3
10
20
30
Display values using 'for' loop in float array:
package ArrayBasics;
public class floatArray {
public
static void main(String[] args) {
// int arr[] = new int[3];
//
Declare float array of size =4
float
farr[] = new float[4];
//
index no always starts from 0 and ends
with size of arr -1. i.e 4-1 =3
// index no varies from 0 to 3 -
0,1,2,3
//
store some float values in array 1.2f,2.2f,3.2f,4.2f in indexno = 0,1,2,3
farr[0]
= 1.2f;
farr[1]
= 2.2f;
farr[2]
= 3.2f;
farr[3]
= 4.2f;
//
length of float array
int
arrLength = farr.length;
System.out.println("arrLength="+arrLength);//
4
// display all values from float arr using 'for'
loop and use length of array
//
length of arr
// for(int i=0;i<=3;i++)
for(int
i=0;i<=farr.length-1;i++)
{ // 4-1
System.out.println("values
from floar array="+ farr[i]);
}
// length
of array =4
// values
from float array =1.2
// values
from float array =2.2
// values
from float array =3.2
// values
from float array =4.2
}
}
HW Define char array and store 2
char values and display all values using for loop
HW Define double array and store
4 double values and display all values using for loop
HW Define long array and store
some 3 values and display all values using for loop
HW Define Boolean array and store boolean 2 values
and display all values using for loop
Default Values in an int Array
In Java, when you create an array of a specific data type, the array
elements are automatically initialized with default values.
For an int array, the default value for each element is 0.
If We don’t store any values in
array, it will store 0 value based on
array type ie. int
package ArrayBasics;
public class
DefaultValsForIntArray {
public
static void main(String[] args) {
int
arr [] =
new int [3];
// if We dont store any values
in array, it will store 0 val based on
array type ie. int
//
Display values from array
System.out.println("default
val for int array ="+ arr[0]);
//
0
System.out.println("default
val for int array ="+ arr[1]);
//
0
//Display
values from array using for loop
System.out.println("Display
values from array using for loop");
// for(int i=0;i<=2;i++)// i =0 -2
for(int
i=0;i<=arr.length-1;i++)// i =0-2
{
System.out.println("default
values from int arr ="+ arr[i]);
}
// values from arr =0
// values
from arr =0
// values
from arr =0
//
store some values 11,21 into arr[0] ,arr[1]
//
Display values from array
System.out.println("ends
here");
}
}
o/p:
default val for int array =0
default val for int array =0
Display values from array using for loop
default values from int arr =0
default values from int arr =0
default values from int arr =0
ends here
Default Values in a float Array
In Java, when you create an array of a specific data type, the array
elements are automatically initialized with default values.
For a float array, the
default value for each element is 0.0f.
package ArrayBasics;
public class
DefaultValsForFloatArray {
public
static void main(String[] args) {
float
fArr[] =
new float [4];
//
if we dont store any values in float arr,
it stores 0.0 by default
//
Display values from float array using for loop
// for(int
i=0;i<=3;i++)// i =0 - 3
for(int
i=0;i<=fArr.length-1;i++)// i =0 - 3
{ // 4-1=3
System.out.println("default
values from float array ="+ fArr[i]);
//
0.0
}
}
}
o/p:
default values from float array
=0.0
default values from float array
=0.0
default values from float array
=0.0
default values from float array
=0.0
HW What is the default value
in a char array?
HW What is the default value in a boolean array?
HW What is the default value in a String array?
Way2 : Initialize values in integer array (or) Store Values in integer
Array at Declaration:
You can initialize an array at
the time of declaration using an array initializer. This is a straightforward
way to define and assign values to an array.
Syntax:
datatype[] arrayName = {value1, value2, value3, ...};
int[] arr = {10, 20, 30, 40, 50};
In this example, the arr array is created with 5 elements, and each
element is initialized to the values specified in the curly braces.
package ArrayBasics;
public class InitialiseValsInArr
{
public
static void main(String[] args) {
// way 1: Declare int array and store 3 values
// int arr [] = new
int [3];
//
// arr [0] =10;
// arr [1] =20 ;
// way 2: 10,20,30
//
We can store values in arary in single line
int
arr[] = {10,20,30,40,50};
// values
at index=0 1 2
3 4
//
length of array
int l =
arr.length;
System.out.println("length
of array ="+ l);
// 5
//
display all values from array using for loop
for(int
i=0;i<=l-1;i++)// index no = 0 - 4
{ //
5<=4 false,
System.out.println("values
from array using for loop="+ arr[i]);
}
}
}
o/p:
length of array =5
values from array using for
loop=10
values from array using for
loop=20
values from array using for
loop=30
values from array using for
loop=40
values from array using for
loop=50
Way2 : Initialize values in float array (or) Store Values in float
Array at Declaration:
package ArrayBasics;
public class
InitialiseValsInFloatArr2 {
public
static void main(String[] args) {
// Intialise values in float array (or) Store
Values in float Array:1.2f , 2.2f, 3.3f
float
farr [] = {1.2f,2.2f,3.3f,4.25f};
// 0 1
2 3
//
length of array
int l =
farr.length;
System.out.println("length
of array ="+ l);//4
//
display values from float array using length of array
// for(int i=0;i<=3;i++)// i=0 -3
for(int
i=0;i<=l-1;i++)// i=0 -3
{
System.out.println("values
from array using for loop="+ farr[i]);
}
}
}
o/p:
length of array =4
values from array using for
loop=1.2
values from array using for
loop=2.2
values from array using for
loop=3.3
values from array using for
loop=4.25
HW define long array and store values using
2nd way {120,12313,24214} and display values from arr
HW define double array and store values using
2nd way and display values from arr
HW define Boolean array and store values using
2nd way and display values from arr
HW define char array and store values using
2nd way and display values from arr
Way2 : Intialise values in
String array (or) Store Values in String Array at declaration:
package ArrayBasics;
public class StringArray {
public
static void main(String[] args) {
//
"ram" , "sita", "abc123"
String
sarr [] = {"ram" ,
"sita", "abc123"};
// 0 1 2
- index no
System.out.println("1st
val =" + sarr[0]); // ram
//
HW get all values from string array using 'for' loop
}
}
For loop without condition:
for(int i=1;i<=3;i++)
{
}
2. syntax :
for(;;) // if there is no
condition in for loop, condi-is always
true
{
}
If there is no condition
specified in the for loop,
the condition is always considered true.
- it goes to infinite loop
package ArrayBasics;
public class ForLoopwithoutcondi
{
public
static void main(String[] args) {
for(;;)
{
// no cond- condi is always true
// no cond-
condi is always true
System.out.println("stmt-1");
System.out.println("stmt-2");
}
}
}
o/p:
stmt-2
stmt-1
stmt-2
stmt-1
stmt-2
stmt-1
stmt-2
....
..... infinite loop
For-Each Loop:
The for-each loop is used to
iterate over arrays or collections in Java.
It can be used to get/ retrieve values
from array / collection obj
It provides a simpler way to
traverse through elements without using an index.
syntax :
for(datatype eachVal : arrVariableName)
{
}
· datatype: The type of elements in the array or collection.
· eachVal: A variable that represents each element of the
array or collection during iteration.
· arrVariableName: The
array or collection being traversed.
Display Values from int Array using 'for each' loop:
package ArrayBasics;
public class
DisplayValsFromIntArray {
public
static void main(String[] args) {
// define int array
int
iarr [] = {11,22,33,44};
// 0 1
2 3
// display all values using 'for each' loop
for(int
x :iarr)
{//
// gets each val from iarr and store each val in to variable i.e x
System.out.println("values
from array using for each loop="+ x );
}
}
}
o/p:
values from array using for each
loop=11
values from array using for each
loop=22
values from array using for each
loop=33
values from array using for each
loop=44
Display Values from float Array
using for each loop:?
package ArrayBasics;
public class
DisplayValsFromFloatArrayUsingForEachLoop {
public
static void main(String[] args) {
float farr []
= {1.1f, 2.1f, 3.1f, 4.1f};
// 0 1
2 3
//
display all values "for each"
loop
for(float x
:farr)
{//
gets each values from float array and store into variable i.e x
System.out.println("values from float
array using for each loop="+ x);
}
}
}
o/p:
values from float array using for
each loop=1.1
values from float array using for
each loop=2.1
values from float array using for
each loop=3.1
values from float array using for
each loop=4.1
HW store some values in long array and gets all values using 'for each' loop?
HW store some values in double array and gets all values using 'for each' loop?
HW store some values in char array and gets all values using 'for each' loop?
HW store some values in boolean array and gets all values using 'for each' loop?
Display Values from String Array using for each loop:
package ArrayBasics;
public class
StringgArrUsingForEachLoop {
public
static void main(String[] args) {
String
sarr [] = {"Ram",
"Sita", "Raju"};
// 0 1
2
//Display
Values from String Array using 'for each' loop:
for(String eachVal
: sarr )
{
System.out.println("values
from String array using for each
loop="+ eachVal);
}
System.out.println("After
for each loop");
}
}
o/p:
values from String array using for each loop=Ram
values from String array using for each loop=Sita
values from String array using for each loop=Raju
After for each loop
Note:
· No
Condition Required: In a for-each loop, there is no need to specify any
condition. The loop automatically iterates through all elements.
· No Index
Required: You do not need to use an index number to access elements. The
loop handles this internally.
· Forward Direction: The loop retrieves
values in a forward direction through the array or collection. It does not
support iterating in reverse direction.
For Loop with Index:
· Condition
Required: You must specify a condition in a for loop to control the
iteration.
· Index
Usage: To access values from an array, you need to use the index number,
e.g., arr[0], arr[1].
· Direction Flexibility: You can iterate
through values in both forward and reverse directions using a for loop with
index numbers.
Here’s a
tabular comparison between the for loop with index and the for-each loop:
|
Feature |
For Loop with Index |
For Each Loop |
|
Syntax |
for(initialization; condition;
increment/decrement) { ... } |
for(datatype eachVal :
arrVariableName) { ... } |
|
Condition |
Requires
a condition to control the loop. |
No
condition is needed. |
|
Index
Usage |
Uses an
index to access array elements (e.g., arr[i]). |
Does
not use indices; directly accesses elements. |
|
Direction |
Can
iterate in both forward and reverse directions. |
Always
iterates in forward direction. |
|
Access
to Index |
Provides
access to the current index of the array. |
Does
not provide access to the index. |
|
Complexity |
More
complex; requires explicit handling of indices and conditions. |
Simpler
and more concise. |
|
Use Case |
Useful
when the index is needed for calculations or operations. |
Best
used when you only need to access each element in sequence. |
|
Modification
of Array |
Can
modify elements of the array using index. |
Cannot
modify the array directly; used for read-only access. |
|
Performance |
Slightly
more overhead due to index calculations. |
Generally
faster for simple iterations. |
package ArrayBasics;
public class
StringgArrUsingForEachLoop2 {
public
static void main(String[] args) {
String
sArr [] = {"Ram",
"Sita", "Raju"};
// 0 1
2
//Display
Values from String Array using for each loop:
for(String
x :sArr)
{
System.out.println("gets
values from String array using for each loop:"+ x);
}
System.out.println("After
for each loop");
//
display values in reverse order - for loop
but not for each loop
// Raju
Sita Ram
// for(int i=2;i>=0;i--)
for(int
i=sArr.length-1;i>=0;i--)
{// i=3-1 4>=0 true, enterd forloop
// arr[2]
//
arr [1]
// arr [0]
System.out.println("get
values from array in reverse direction ="+
sArr[i]);
//
sArr[4]
}
}
}
o/p:
gets values from String array
using for each loop:Ram
gets values from String array
using for each loop:Sita
gets values from String array
using for each loop:Raju
After for each loop
get values from array in reverse
direction =Raju
get values from array in reverse
direction =Sita
get values from array in reverse
direction =Ram
types of array:
1. single dimensional array
2. Multi dimensional array
1.single dimensional array :
int arr[] =
new int[3];
( or) int [] arr = new int [3];
2.Two-Dimensional Arrays:
·
Represents a table with rows and columns
·
Each element can be accessed using two indices:
row and column.
//
Declare 2 dim array
data
can be stored in the form of rows, columns m,n
Syntax :
datatype [] [] arrName = new
dataType [m][n];
(or)
datatype arrName [] [] = new dataType [m][n];
//
m = no of rows - Rowno no varies from 0 - (m-1)
//
n -no of columns- columms no varies from
0 to (n-1)
package ArrayBasics;
public class TwoDimArr {
public
static void main(String[] args) {
//
Declare 2 dim int -array and store 2
rows and 3 columns
int
[][] arr = new int[2][3];
//
4 index no varies from 0- 3
//
m = no of rows - 2 respresents rows
no varies from 0 -1 (0 - 2-1=1)
//
n -no of columns- 3 -- columms
varies from 0 to 2(0- 3-1=2)
// store some value in 2 dim array
// 0,0 , 0,1, 0.2
arr
[0][0] = 00;
// 00 will be stored in arr at row no= 0 colno =0
arr
[0] [1] = 01;
// row no =0 colno= 1
arr
[0] [2] = 02;
//
1, 0 1,1 1,2
arr
[1] [0] = 10;
arr
[1] [1] = 11;
arr
[1] [2] = 12;
//
display val at index 0,0
System.out.println("display
val at 0,0 cell =" + arr[0] [0]);
// 00
---> 0
//display
val at index 0,1
System.out.println("display
val at 0,1 cell =" + arr[0] [1]);
// 01
--> 1
// display
val at index 10
System.out.println("display
val at 1,0 cell =" + arr[1] [0]);
// 10
// display
val at index 11
System.out.println("display
val at 1,1 cell =" + arr[1] [1]);
// 11
//
Hw display values 0,2
//HW display values 1,2
}
}
o/p:
display val at 0,0 cell =0
display val at 0,1 cell =1
display val at 1,0 cell =10
display val at 1,1 cell =11
ex2: get all values from 2 dimensional array using for loops
// 00
01 02
// 10
11 12
package ArrayBasics;
public class
GetAllValsFrom2DimArrayUsingForLoops {
public
static void main(String[] args) {
//
Declare 2 dim int- array of 2 rows and 2 columns
int
arr[] [] = new int [2] [3]; //
4 index no varies from 0- 3
//
m = no of rows - 2 respresents rows,
index no varies from 0 -1
//
n -no of columns- 3 -- columms , index - 0 to 2
// store some value
arr
[0] [0] = 00;
arr
[0] [1] = 01;
arr
[0] [2] = 02;
//
10 1 1 , 12
arr
[1] [0] = 10;
arr
[1] [1] = 11;
arr
[1] [2] = 12;
//
get all values from 2 dimensional array using
for loop
// 00 01 02
// 10 11 12
for(int
i=0;i<=1;i++) // vary no of rows i=0,
0+1 =1, 1+1=2
{// 0<=1, true, it enters outer for loop
// 1<=1
true, it enters outer for loop
// 2<=1 , false, ctrls goes after outer
for loop
for(int
j =0;j<=2;j++) // to vary no of columns// j =0, 0+1=1, 1+1 =2, 2+1 =3
{// 0<=2, true ,it enters inner for loop
// 1<=2, true ,it enters
inner for loop
// 2<=2 , true ,,it enters inner for loop
// 3 <=2 , false , ctrl goes after inner for loop
//
arr [0][0] , arr [0] [1], arr [0] [2]
System.out.println("values
from 2 dim arr="+ arr[i][j]);
//
arr[1][0] --> 10
// arr
[1] [1] -->11
//
[1] [2] --> 12
// ctrl goes for increment
}//
end of inner for loop
// ctrl will go to outer for loop
}//
end of outer for loop
}
}
o/p:
values from 2 dim arr=0
values from 2 dim arr=1
values from 2 dim arr=2
values from 2 dim arr=10
values from 2 dim arr=11
values from 2 dim arr=12
// HW Define 2 Dim float array of size 1 , 2 and store some values and display all values
using for loop
// HW Define
2 Dim String aray of size 3 , 4
and store some values and display all values using for loop
Getting Rows and Columns Count in a Two-Dimensional Array:
package ArrayBasics;
public class
GetRowsColumnsCntFrom2DimArray {
public
static void main(String[] args) {
//
Declare 2 dim int array with 2 rows cols= 3
int
[][] arr = new int [2] [3];
// 1 dim arr-
int [] arr = new int [3]; length of array -- > arr.length = 3
// 0 ,
1 ,2
// rows cnt
-- form 2 dim array
System.out.println("rows
cnt -- form 2 dim array ="+
arr.length);
// rowsCnt = 2
//
Columns cnt form 2 dim array
System.out.println("Columns
cnt form 2 dim array ="+
arr[0].length);
//
3
}
}
HW use
rows cnt and columns cnt in for loop to display all values from 2 dim
array ?
HW define int array of 3 rows and
2 columns, store some values, displays all values from 2 dim array using for
loop?
HW define String array of 2 rows
and 3 columns, store some values, displays all values from 2 dim array using
for loop?
HW define char array of 1 row and
2 columns, store some values, displays all values from 2 dim array using for
loop?
FAQ SearchForGivenNoInArray :
//
check given no is exist in array or not
package ArrayBasics;
public class
SearchForGivenNoInArray {
public
static void main(String[] args) {
//
// check given no is exist in array or not
int
arr [] = {10,20,30,40};
// 0
1 2 3
//check
array contains 20 or not --> display
msg 'arr contains 20'
// else
display msg "arr does not contain 20"
boolean
flag = false;
// int expectedNo =20;
int
expectedNo =25;
for(int
i=0;i<=arr.length-1;i++) // i= 0, 0+1 =1, 1+1 =2, 2+1 =3, 3+1 =4
{
// 0<=3 true, for loop
// 1<=3 true , for loop
// 2<=3 true, for loop
// 3<=3 true , for loop
// 4<=3 false,out of for loop
// System.out.println(arr[i]);
if(arr[i]
== expectedNo )
// if(arr[i] == 25 )
{// arr[0]
10 ==25 false,
//arr[1]
20 ==25 false
//
arr[2] 30 == 25 false
//
arr[3] 40 == 25 false
// System.out.println("arr
contains "+expectedNo);// displays
// System.out.println("I
found"+expectedNo+" value. so
coming out of for loop");
flag
= true;
break;
}
else
{
// System.out.println("arr
does not contain 20");
}
//
ctrl - will go for increment
}//
end of for loop
if(flag
== true)
{//
false true
System.out.println("arr
contains "+expectedNo);
}
else
{
System.out.println("arr
does not contains "+expectedNo);
}
System.out.println("end
of program");
}
}
FAQ: WAP to Count Occurrences of
a Given Character in a Char Array
char chArr []
= { 'r' , 'a', 'm','a'}
'a' char count - 2 times
'r' -1 time
// Given char is not found , cnt =0
package ArrayBasics;
public class CharacterCntInArray
{
public
static void main(String[] args) {
char chArr []
= { 'r' , 'a', 'm','a'};
/// 0 1
2 3
// 'a'
char count - 2 times
//
'r' -1 time
// Given char is not found , cnt =0
// 'Z' - cnt =0
// char expectedChar = 'a';
// char
expectedChar = 'r';
char expectedChar = 'Z';
int cnt =0;
for(int i=0;i<=chArr.length-1;i++)// i=0,
0+1 =1, 1+1 =2, 2+1=3, 3+1 =4
{
// 0<=3 , true , for loop
//
1<=3 , true . forloop
//
2<=3 , true ,forloop
//
3<=3 , true , for loop
//
4<=3 , false., after for loop
//
System.out.println("values from array="+ chArr[i]);
if(chArr[i] == expectedChar)
{ // charr[0] r == 'a', false,ctrl goes after if block
//
charr[1] a == 'a' , true , enters if block, increase the cnt by1
// charr[2] m == a, false
// charr[3] a == a, true , enters if block
//
increase the cnt by 1
cnt =
cnt +1;
// 1
+ 1 = 2
//
cnt =2
}
//
ctrl goes for increment
}// end of for
loop
// Display the cnt of given char
System.out.println("Expected char
="+ expectedChar + " count ="+ cnt);
// a 2
}
}
FAQ // WAP to get vowels count
from char array ?
// Vowels :
a e i o u
char
chArr [] = { 'r' ,'a', 'm','a','e','i'};
// vowels cnt
= 4 - cnt = 0 +1= 1 +1=2 +1=3 +1 =4
package ArrayBasics;
public class VowelCntInArray2 {
public
static void main(String[] args) {
char
chArr [] = { 'r' ,'a', 'm','a','e'};
// 0 1
2 3 4
// vowels cnt
= 3 - cnt = 0 +1= 1 +1=2 +1=3
int
vowelsCnt = 0;
for(int
i=0;i<=chArr.length-1;i++)// i=0. 0+1=1, 1+1 =2, 2+1 =3, 3+1 =4, 4+1 =5
{ // 0<=4 , true , for loop
// 1<=4 true, for loop
// 2<=4 , true , for loop
// 3<=4 , true for loop
// 4<=4, true for loop
// 5<=4
falsse, after forloop
// System.out.println(chArr[i]);
//
check each char == vowel or not
// a ,e i , o ,u
if(chArr[i]==
'a' || chArr[i] == 'e' || chArr[i] == 'i' || chArr[i] == 'o' || chArr[i] ==
'u')
{// charr[4] charr[1]
// e == a e== e e == i e == o e==u
//
f || tr || f ||
f || f
// true
vowelsCnt
= vowelsCnt +1;
// 2+1 =
// vowelsCnt = 3
}
// ctrl goes for increment
}
//
display the cnt after for loop
System.out.println("vowelsCnt
="+vowelsCnt);
// 3
//
}
}
HW Same program use 'for each'
loop and multiple if conditions
hint:
if(eachVal==
'a' )
{
vowelsCnt
= vowelsCnt + 1 ;
}
if(eachVal==
'e' )
{
vowelsCnt
= vowelsCnt + 1 ;
}
----------------
HW FAQ WAP to get consonants
count from char array ?
r a m a
consonants cnt = 2
HW same program use 'for each'
loop ?
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