Loops in Java programming language
Loops in Java programming language
In this tutorial, we will discuss Loops in Java programming language
In some cases, if you want to execute a block of the statement multiple times according to a condition, such case loops are used to perform this action.
Looping structure in programming languages is a feature which helps to execute a block of instruction(continuous instruction or function or task) repeatedly while some conditions and evaluate until becomes true.
Loops in Java programming language
Java language contains some loops which are functioning similarly. it uses to helps to perform some continuous task until the given condition is fulfilled.
We will discuss in this part all Loops in Java programming language
1) While loop –
A “while loop” is a Loop statement. That allows the code( flow of control ) to be executed repeatedly to perform based on the given Boolean expression for a certain number of times.
Syntax
initilaization;
while(boolean_Expression)
{
//loop body
looping statements
increment/decrement statements
}
Flowchart
First the “while loop” starts with the initialization of statement only once, then it checks the Boolean-expression. If it is evaluated as true then the loop body of statements are executed. If it is evaluated as false, the flow of control exits from the loop body and moves to the end of the loop.
When the loop is evaluated true. the body of statements are executed and the flow of control goes to updating statements and then, test Boolean-expression is evaluated again to executed the body of the statement.
This process is followed until the Boolean-expression returns false.
Example
//Java program to illustrate while loop
class Demo_While{
public static void main(String args[]){
int i=0;//declare variable "i" and initialize as zero
while(i<=5){
System.out.println("Value of i: "+i);
//this statement execute until this condition(become greater than 5) performed
i++;
//increment the value of i for next ikteration
}
}
}
When the above code is executed, it produces the following result
value of i=0 value of i=1 value of i=2 value of i=3 value of i=4 value of i=5
Know more about this
while loop in Java language
Nested while loop in Java language
2) for loop –
The for loop is a looping structure. It allows their code (flow of control) to be executed repeatedly to perform based given boolean expression to a certain number of times., as same as while loop but with some differences.
Although for loop and while loop both have same flow of control, but the for loop structure distinguished with the while loop.
In the for loop, initialization statements, boolean expression, updating statements are defined as the same line
Syntax
for(initialization_statements; boolean_Expression; increment/decrement){
//loop body looping statements
}
Flowchart
First, the “for loop” starts with the initialization statement only once. and then checks the boolean-expression. If it is evaluated as true then the loop body of statements are executed or If it evaluated as the false flow of control exits from the loop body and goes to the end of the loop.
When the loop is evaluated true. the body of statements is executed, then the flow of control goes for updating statements and test boolean expression is evaluated again to executed the body of the statement.
This process follows until the boolean expression returns false.
Example
//Java program to illustrate for loop
class Demo_For1{
public static void main(String args[]){
int i;//declare variable "i";
for(i=0; i<=5; i++){
System.out.println("Value of i: "+i);
//this statement execute until this condition(become greater than 5) performed
//increment the value of i for next ikteration
}
}
}
When the above code is executed, it produces the following result
value of i=0 value of i=1 value of i=2 value of i=3 value of i=4 value of i=5
Know more about this
for loop in Java language
Nested for loop in Java language
3) do-while loop –
The do while loop is similar to while loop with the only difference that it starts with the execution of statements before the test condition is checked. If the test expression returns false as the first time, the statements execute only once and loop exit from the execution
do-while is a looping structure. It allows their flow of control access repeatedly to perform based given boolean expression as same as while loop but with some differences. The do-while loop structure distinguishes with the while loop structure.
In the do -while loop, initially, statements are executed only once then flow of control moves for updating-statements. Then it starts to evaluate test condition and it(flow of control )begins to work as a normal while loop.
Syntax
for(initialization_statements; boolean_Expression; increment/decrement){
//loop body looping statements
}
Example
class DoWhileLoopEx{
public static void main (String args[]){
int i=1;
do{
System.out.println(i);
i++;
}while(i<=10);
}
}
When the above code is executed, it produces the following result
1 2 3 4 5 6 7 8 9 10
Flowchart
Know more about this
do-while loop in Java language
Nested do-while loop in Java language
4) Enhanced for loop –
Java language is introduced to another type of for loop in Java 5. It is called as Enhanced for loop(for each loop) to iterate through the elements of a collection of an array.
you can see in this blog how to use enhanced for loop to iterate the one-dimensional array, two-dimensional array and three-dimensional array elements in Java.
Enhanced for loop is used only to iterates through the elements in a sequential manner without knowing currently processing elements.
Syntax
for(elements:Collection obj/array)
{
statements
}
Example
class Java_for_each{
public static void main(String args[]){
int marks[]={56,78,98,54,67}; // array declaration and initialization
for(int i:marks){
System.out.println(i);
}
}
}
When the above code is executed, it produces the following result
56 78 98 54 67
Know more about this
Enhanced for loop in Java language
Suggested for you
Single dimension array in Java language
Two dimension array in Java language
three dimension array in Java language
1 Comment
Juma Onyango Benard November 12, 2019 at 11:24 am
Great experience ?