The String::formatted method in Java is a concise way to format strings using placeholders, similar to the String::format method but with a cleaner syntax. It was introduced in Java 15, and it allows you to replace placeholders in a string with specified values.

The syntax of the formatted method is straightforward:

String formattedString = "Your name is %s and your age is %d".formatted("John", 25);

Here’s how it works:

1. The placeholders in the string (such as %s, %d) follow the same format specifiers as used in String.format().
   • %s: Formats strings.
   • %d: Formats integers.
   • %f: Formats floating-point numbers.
   • And so on.
2. The formatted() method takes the format arguments in the exact order of appearance of the placeholders.

Example Usage:

Here are a few examples illustrating the different use cases:

Example 1: Format a simple text

String result = "Hello, %s!".formatted("Alice");
System.out.println(result);
// Output: Hello, Alice!

Example 2: Combine multiple placeholders

String summary = "Product: %s, Quantity: %d, Price: $%.2f".formatted("Widget", 10, 9.99);
System.out.println(summary);
// Output: Product: Widget, Quantity: 10, Price: $9.99

Example 3: Use with text blocks

In text blocks, you can similarly use the formatted method to insert values dynamically:

String jsonTemplate = """
    {
        "name": "%s",
        "age": %d,
        "email": "%s"
    }
    """;

String json = jsonTemplate.formatted("John", 30, "[email protected]");
System.out.println(json);
// Output:
// {
//     "name": "John",
//     "age": 30,
//     "email": "[email protected]"
// }

Key Points:

• The formatted method is directly callable on the string you want to format, making the code cleaner.
• It has the same capabilities as String.format, so it supports all format specifiers.
• formatted works particularly well with text blocks for clean and readable multi-line string formatting.

This method is helpful for writing concise and fluent code without the need to call String.format explicitly.