Java Do-While Loops
The `do-while` loop is a post-test loop. It executes its code block FIRST, and only then tests the condition at the bottom. This guarantees that the loop body will ALWAYS execute at least once, regardless of whether the initial condition is true or false.
"A do-while loop is like a restaurant that serves you the appetizer first and checks your membership card after. You are guaranteed at least one bite."
Deep Dive: How It Works
Syntax: `do { /* statements */ } while (condition);`
Notice the semicolon `;` required at the end after `while(condition);`.
Commonly used for interactive menu systems and prompt re-tries where you must prompt the user at least once before validating input.
Syntax Blueprint
int x = 10;
do {
System.out.println(x);
x++;
} while (x < 5);Prints 10 once, even though 10 < 5 is false right from the start.
Core Rules to Remember
Common Beginner Traps & How to Fix Them
Forgetting the semicolon after while (condition);Why it happens: Unlike standard while loops, do-while requires a semicolon after the closing parenthesis.
How to fix: Always write while (condition); with a final semicolon.
Live Interactive Example
Hit Run Code to see it liveYour Turn: Micro Challenge
No pressure! Edit the starter code below and test your solution with instant feedback.
Write a do-while loop
- Initialize int step = 1; write a do-while loop that prints "Step " + step while step <= 3.
- Remember to increment step inside the loop.
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