Module 10: Strings, Files, and Everyday Core APIs
Formatting Output with printf and format
Format numbers, text, and aligned output so your programs look cleaner and easier to read.
Author
Java Learner Editorial Team
Reviewer
Technical review by Java Learner
Last reviewed
2026-04-17
Java version
Java 25 LTS
Learning goals
- Use placeholders for clearer output formatting
- Format numbers and labels more predictably
- Keep display logic separate from raw data values
Formatting improves readability: Instead of stitching raw values into messy text, placeholders keep output shape predictable.
String.format() is useful for reports, receipts, and aligned output: You can control decimal places, text placement, and spacing.
This matters beyond the console: Good formatting habits carry into logs, exports, and generated emails.
Think in two steps: first compute the data, then format it for display.
Runnable examples
Format money with two decimals
double total = 19.5;
String line = String.format("Total: $%.2f", total);
System.out.println(line);Expected output
Total: $19.50
Mini exercise
Format a product name and price using `String.format()` so the price always shows two decimal places.
Summary
- Formatting makes output easier to scan.
- `String.format()` is useful for reports and receipts.
- Compute values first, then format them for display.
Next step
Next, search and validate text patterns with regular expressions.
Sources used