Java Loop Control

Loops are used to execute a set of statements repeatedly until a particular condition is satisfied.

Java has three types of loop:

• for loop
• while loop
• do…while loop

let’s talk about them one by one.

for loop

Syntax of for loop:

for(initialization; condition ; increment/decrement)
{
   statement(s);
}

Example

The code below will print 0123456789. we init a variable counter and give it a initial value 0, if the counter is less than 10 then the code inside the curly braces will be executed.

Once the counter is not less than 10 then the loop end.

public static void forLoopDemo() {
  for (int counter = 0; counter < 10; counter++) {
    System.out.print(counter);
  }
}

output

0123456789

while loop

Syntax of while loop

while(condition)
{
   statement(s);
}

Example

public static void whileLoopDemo() {
  int counter = 0;
  while (counter < 10) {
    System.out.println(counter);
    counter++;
  }
}

output:

1
2
3
4
5
6
7
8
9

do…while loop

Syntax of do-while loop:

do
{
   statement(s);
} while(condition);

How do…while loop works

First, the statements inside loop execute and then the condition gets evaluated, if the condition returns true then the control gets transferred to the “do” else it jumps to the next statement after do-while.

Example

public static void doWhileLoopDemo() {
  int i = 10;
  do {
    System.out.println(i);
    i--;
  } while (i > 0);
}

output:

9
8
7
6
5
4
3
2
1

Source code

Github