Looping Statement in Java
15:10:00
Looping Statement in Java
Looping statement is the statements execute one or more statement repeatedly
several number of times. In java programming language there are three types of
loops; while, for and do-while.
Why use loop?
When you need to
execute a block of code several number of times then you need to use looping
concept in Java language.
Advantage with
looping statement
- Reduce length of Code
- Take less memory space.
- Burden on the developer is reducing.
- Time consuming process to execute the program is reduced.
Difference
between conditional and looping statement
Conditional
statement executes only once in the program where as looping statements
executes repeatedly several number of time.
While loop
In while loop first check the condition if condition
is true then control goes inside the loop body otherwise goes outside of the
body. While loop will be repeats in clock wise direction only.
Syntax
while(condition)
{
Statement(s)
Increment / decrements (++ or --);
}
Example while
loop
class whileDemo
{
public static void main(String args[])
{
int i=0;
while(i<5)
{
System.out.println(+i);
i++;
}
Output
1
2
3
4
5
for loop
for loop is a statement which allows code to be repeatedly executed.
For loop contains 3 parts Initialization, Condition and Increment or Decrements
Syntax
for ( initialization; condition; increment )
{
statement(s);
}
·
Initialization: This step is execute first and this is execute only once when we
are entering into the loop first time. This step is allow to declare and
initialize any loop control variables.
·
Condition: This is next step after initialization step, if it is true, the
body of the loop is executed, if it is false then the body of the loop does not
execute and flow of control goes outside of the for loop.
·
Increment or Decrements: After completion of Initialization and Condition steps loop body
code is executed and then Increment or Decrements steps is execute. This
statement allows to update any loop control variables.
Flow Diagram
Control flow of for loop
- First initialize the variable
- In second step check condition
- In third step control goes inside loop body and execute.
- At last increase the value of variable
- Same process is repeat until condition not false.
Improve your
looping conceptFor Loop
Display any
message exactly 5 times.
Example of for
loop
class Hello
{
public static void main(String args[])
{
int i;
for (i=0: i<5; i++)
{
System.out.println("Hello Friends !");
}
}
}
Output
Hello Friends !
Hello Friends !
Hello Friends !
Hello Friends !
Hello Friends !
do-while
A do-while loop is similar to a while loop,
except that a do-while loop is execute at least one time.
A do while loop is
a control flow statement that executes a block of code at least once, and then
repeatedly executes the block, or not, depending on a given condition at the
end of the block (in while).
When use do..while loop
when we need to
repeat the statement block at
least one time then ues
do-while loop. In do-while loop post-checking process will be occur, that is
after execution of the statement block condition part will be executed.
Syntax
do
{
Statement(s)
increment/decrement (++ or --)
}while();
In below example
you can see in this program i=20 and we chech condition i is less than 10, that
means conditon is false but do..while loop execute onec and print Hello world !
at one time.
Example
do..while loop
class dowhileDemo
{
public static void main(String args[])
{
int i=20;
do
{
System.out.println("Hello world !");
i++;
}
while(i<10);
}
}
Output
Hello world !
Example
do..while loop
class dowhileDemo
{
public static void main(String args[])
{
int i=0;
do
{
System.out.println(+i);
i++;
}
while(i<5);
}
}
Output
1
2
3
4
5
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