Observations on the do loop

Since the condition of end of loop is evaluated only after the body of the loop has been executed, it follows that:

• The body of the loop is executed at least once. Hence, the do loop should be used in those cases where we need to repeatedly execute some statements, and would like that these statements are executed at least once.
• In general, it is not necessary to initialize the variable that appear in the loop condition before the loop. It is sufficient that these variables are initialized in the body of the loop itself (notice that this is different from while loops).

Example: Sum integers read from input until a 0 is read.

int i;
int sum = 0;
do {
  i = Integer.parseInt(JOptionPane.showInputDialog(
                         "Input an integer (0 to terminate)"));
  sum = sum + i;
} while (i != 0);
System.out.println("sum = " + sum);

Note that the syntax of the do statement requires that there is a 't' after  while (condition). To increase readability of the program, and in particular to avoid confusing the   while (condition);   part of a do loop with a while statement with empty body, it is in any case better to include the body of the do loop in a block, and indent the code as follows (as shown also in the example above):

do {
  statement
} while (condition);