String Formatting

Simple + concatenation works fine for a quick message, but once you need aligned columns, controlled decimal precision, or the same message built from different values repeatedly, Java's formatted output tools become far more readable and maintainable.

String.format() and printf-Style Specifiers

String.format() builds a formatted String using a template with placeholders called format specifiers. System.out.printf() works exactly the same way, except it prints the result directly instead of returning it.

Specifier	Meaning
%d	Integer value
%s	String value (works with almost any type)
%f	Floating-point value
%.2f	Floating-point value, 2 digits after the decimal
%n	Platform-independent newline

String.format and printf

Java

public class FormatDemo {
    public static void main(String[] args) {
        String name = "Aman";
        int age = 28;
        double price = 19.999;

        String message = String.format("Name: %s, Age: %d", name, age);
        System.out.println(message);

        System.out.printf("Price: $%.2f%n", price);
        System.out.printf("%s is %d years old.%n", name, age);
    }
}

Name: Aman, Age: 28
Price: $20.00
Aman is 28 years old.

Note

%.2f rounds to 2 decimal places — notice 19.999 became 20.00, not 19.99. The number after the dot in a float specifier controls precision, and Java rounds rather than truncates.

Tip

Use %n instead of the literal \n inside format strings. %n produces the correct newline sequence for whatever operating system the program is running on, while \n always produces a Unix-style newline regardless of platform.

Padding and Aligning Output

Format specifiers also support width and alignment, which is especially useful for printing tabular data in the console.

Column alignment with width specifiers

Java

public class TableFormatDemo {
    public static void main(String[] args) {
        System.out.printf("%-10s%5s%n", "Item", "Qty");
        System.out.printf("%-10s%5d%n", "Apples", 12);
        System.out.printf("%-10s%5d%n", "Bananas", 7);
    }
}

Item           Qty
Apples          12
Bananas          7

Note

%-10s left-aligns a string within a 10-character field; %5d right-aligns an integer within a 5-character field. Combining these is the standard trick for producing readable, column-aligned console output.

Text Blocks: A Modern Alternative for Multi-Line Strings

When you need a large, multi-line chunk of text — an HTML snippet, a JSON payload, a SQL query — manually concatenating lines with + and \n gets messy fast. Java 15+ introduced text blocks, a cleaner way to write multi-line string literals directly in your source code. They're covered in full on the dedicated Text Blocks page, but here's a quick preview:

A text block (Java 15+)

Java

public class TextBlockPreviewDemo {
    public static void main(String[] args) {
        String html = """
                <html>
                    <body>
                        <p>Hello, World!</p>
                    </body>
                </html>
                """;

        System.out.println(html);
    }
}

Choosing Between + and Formatted Output

Situation	Recommended Approach
One or two values, simple message	concatenation
Controlling decimal precision	String.format() / printf with %.Nf
Aligned, tabular console output	printf with width specifiers
Large multi-line text	Text blocks

Tip

+ concatenation is perfectly fine — and often more readable — for simple, one-off messages. Reach for String.format() or printf once you need precision control, alignment, or the same template applied to many different values.