Java – While Loop
A loop statement allows a programme to repeat a set of instructions under certain conditions. This allows a programmer to build programmes with fewer lines of code and improve the readability of the code. To meet looping requirements, Java includes the following types of loops:
- while loop
- do-while loop
- for loop
The While Loop
A Java While Loop lets you repeat a sequence of statements as long as a certain condition is true. The Java While Loop may be thought of as a looped if statement.
Syntax
while (condition) {
statements;
}
Flow Diagram:
In the example below, the programme utilises a while loop to add all numbers from 1 to 5.
public class MyClass {
public static void main(String[] args) {
int i = 0;
int sum = 0;
while (i <= 5) {
sum = sum + i;
i++;
}
System.out.println(sum);
}
}
The output of the above code will be:
15
The Do-While Loop
The do-while loop is a version of the while loop in which statements are executed before the conditions are checked. As a result, the do-while loop runs each statement at least once.
Syntax
do {
statements;
}
while (condition);
Flow Diagram:
The do-while loop in the example below executes the statements once even if the condition is not met.
public class MyClass {
public static void main(String[] args) {
int i = 10;
int sum = 0;
do{
sum = sum + i;
i = i+1;
}
while (i <= 5);
System.out.println(sum);
}
}
The output of the above code will be: