Summary

Introduce instance versions of the existing String::format method.

This will be a preview language feature as part of Text Blocks

Problem

The static forms of String::format lack a flowiness that is expected in modern Java code. Text Blocks significantly emphasize this condition.

Example:

        String type = "Integer";
        String variable = "value";

        String source = String.format("""
                        public void print(%s %s) {
                            System.out.println(Objects.toString(object));
                        }
                        """, type, variable);

In this example, the format is not the focus of the expression, and the argments are near invisible,

Solution

Provide instance versions of format methods.

        String type = "Integer";
        String variable = "value";

        String source = """
                        public void print(%s %s) {
                            System.out.println(Objects.toString(object));
                        }
                        """.formatted(type, variable);

Using String instance "format" splits focus more clearly into 1) the format and 2) the arguments.

Due to method overloading lookup, this solution also requires a unique name other than "format". Hence, the name "formatted".

Alternatives

The argument for implementing String::format as static appears to be that the format methods could be imported statically and thus conduct themselves comparably to C's sprintf .

import static java.lang.String.format;
...
        int result = 10;
        String str = format("This result is %d", result);

However, developers use imported static infrequently and are forced, somewhat redundantly, to add the class selector.

        int result = 10;
        String str = String.format("This result is %d", result);

Specification

    /**
     * Formats using this string as the format string, and the supplied
     * arguments.
     *
     * @implSpec This method is equivalent to {@code String.format(this, args)}.
     *
     * @param  args
     *         Arguments referenced by the format specifiers in this string.
     *
     * @return  A formatted string
     *
     * @see  java.lang.String#format(String,Object...)
     * @see  java.util.Formatter
     *
     * @since 13
     *
     * @deprecated  This method is associated with text blocks, a preview language feature.
     *              Text blocks and/or this method may be changed or removed in a future release.
     */
    @Deprecated(forRemoval=true, since="13")
    public String formatted(Object... args) {
        return new Formatter().format(this, args).toString();
    }