The following code compiles successfully but fails at runtime with a StringIndexOutOfBoundsException:


import java.math.*;
import static java.util.FormatProcessor.*;

public class Foo {
    public static void main(final String[] args) throws Exception {
        final BigDecimal sum = new BigDecimal("12.34");

        final String stringFomat = String.format("Using String.format() - The sum is: %s €", sum); // this works
        System.out.println(stringFomat);

        final String message = FMT."The sum is: %f\{sum} €"; // this fails
        System.out.println(message);
    }
}

javac --enable-preview --source 21 Foo.java
java --enable-preview Foo

Using String.format() - The sum is: 12.34 €
Exception in thread "main" java.lang.StringIndexOutOfBoundsException: Range [21, 21 + 4) out of bounds for length 11
    at java.base/jdk.internal.util.Preconditions$1.apply(Preconditions.java:55)
    at java.base/jdk.internal.util.Preconditions$1.apply(Preconditions.java:52)
    at java.base/jdk.internal.util.Preconditions$4.apply(Preconditions.java:213)
    at java.base/jdk.internal.util.Preconditions$4.apply(Preconditions.java:210)
    at java.base/jdk.internal.util.Preconditions.outOfBounds(Preconditions.java:98)
    at java.base/jdk.internal.util.Preconditions.outOfBoundsCheckFromIndexSize(Preconditions.java:118)
    at java.base/jdk.internal.util.Preconditions.checkFromIndexSize(Preconditions.java:397)
    at java.base/java.lang.String.checkBoundsOffCount(String.java:4849)
    at java.base/java.lang.StringUTF16.checkBoundsOffCount(StringUTF16.java:1625)
    at java.base/java.lang.StringUTF16.inflate(StringUTF16.java:1459)
    at java.base/java.lang.StringLatin1.inflate(StringLatin1.java:771)
    at java.base/java.lang.String.getBytes(String.java:4724)
    at java.base/java.lang.StringConcatHelper.newArrayWithSuffix(StringConcatHelper.java:491)
    at Foo.main(Foo.java:11)