do‑while loop

The do‑while loop executes the block of code once before checking the condition (post‑test). The loop continues as long as the condition is true.

Syntax:

do {
    // loop body
} while (condition);

Example:

int i = 0;
do {
    System.out.println(i);
    i++;
} while (i < 5);

Guaranteed at least one execution:

int x = 10;
do {
    System.out.println("This runs once even if condition false");
} while (x < 5);

Use case: When you need to execute the loop body at least once, e.g., displaying a menu and reading user input until a valid choice.

int choice;
do {
    System.out.println("1. Option 1");
    System.out.println("2. Option 2");
    System.out.println("0. Exit");
    choice = scanner.nextInt();
    // process choice
} while (choice != 0);

Note: The while condition ends with a semicolon.