The do keyword is used along with while keyword to form a do-while loop.
do{
//body of do-while
}while(condition);
Example of do keyword
public class JavaExample {
public static void main(String[] args) {
int i = 0;
do {
System.out.println(i);
i++;
}while (i < 6);
}
}
Output:
Why we need do while when we have while loop?
The main difference between a while loop and do-while is that:
- while loop checks the condition first and then executes the statements inside it.
- do-while loop executes the statements first and then checks for the condition.
You can say that do-while loop executes at least once for any given condition.
public class JavaExample {
public static void main(String[] args) {
//do while
int i = 0;
do {
System.out.println("do-while");
i++;
}while (i > 1000);
//while
int j = 0;
while (j > 1000){
System.out.println("while");
j++;
}
}
}
Output: As you can see, for the exactly same loop condition and scenario, the while loop didn’t execute but the do-while executed once as it checked the condition after first execution.
do-while