The difference between do-while and while is that do-while evaluates its expression at the bottom of the loop instead of the top. Therefore, the statements within the do block are always executed at least once.
int num = 0;
do {
System.out.println("Line " + (num++));
} while (num < 5);
The loop will continue to increment by one on every loop untill it reaches 5.
Java 5 introduced what is sometimes called a “for each” statement that accesses each successive element of an array, List, or Set without the bookkeeping associated with iterators or indexing.
String[] names = {"Michael Maus", "Mini Maus"};
for (String s : names) {
System.out.println(s);
}
the output results
Michael Maus
Mini Maus
The while statement is used to repeat a block of statements while some condition is true. The condition must become false somewhere in the loop, otherwise it will never terminate.
int i = 1;
while (i <= 5) {
System.out.println(i + " squared is " + (i * i));
i++;
}
The output result for the above could would be
1 squared is 1
2 squared is 4
3 squared is 9
4 squared is 16
5 squared is 25
Many loops consist of three operations surrounding the body: (1) initialization of a variable, (2) testing a condition, and (3) updating a value before the next iteration. The for loop groups these three common parts together into one statement, making it more readable and less error-prone than the equivalent while loop. For repeating code a known number of times, the for loop is the right choice.
for(int count = 0; count < 10; count++) {
System.out.println("Line " + (count));
}
The output result for the above could would be
Line 0
Line 1
Line 2
Line 3
Line 4
Line 5
Line 6
Line 7
Line 8
Line 9
